GOINDIS NATUROPATHY TRUST(INDIA)
Charity Registration No.845/4 dated 03.09.2003
UNDERSTANDING
HUMAN BODY FUNCTIONS
SANTOKH SINGH PARMAR
FOUNDER TRUSTEES:
Satyendra Singh Goindi, MSc, LLB, ND
Gurkirpal Kaur Goindi, BA, BEd, DPE, ND
Santokh Singh Parmar, B Arch, Dip TP, Dip LA, MRTPI, AITP, AIIA
Devinder Singh Saroya, PCS
Gurmukh Singh Girn, MSc, MCRP, AITP
Para Nos
1. THE ENDOCRINE SYSTEM
1.1 What is Endocrine System ? 1.2 The Hormones
1.3 The Hypothalamus 1.4 The Central Nervous System
1.6 The Pituitary Gland 1.8 The Thyroid Gland
1.9 The Adrenal Glands 1.11 The Pancreas
1.13 The Pineal Gland 1.15 The Thymus
1.17 The Parathyroid Gland 1.18 The Reproductive Organs
2. THE NERVOUS SYSTEM
2.1 What is Nervous System ? 2.2 The Automatic Nervous System
2.3 The Central Nervous System 2.4 The Peripheral Nervous System
2.5 The Nervous Tissue 2.6 The Neurotransmitters
2.8 The Brain 2.11 Disorders of the Nervous System
2.17 Genetic Disorders 2.18 Concussion
2.19 The Spinal Cord 2.21 Reflexes
2.22 Sensory Receptors and Sense Organs 2.25 Smell and Taste
2.28 The Vision 2.31 Eye Disorders
2.37 Hearing and Equilibrium
3. THE CIRCULATORY SYSTEM
3.1 What is Circulatory System ? 3.2 Composition of Blood
3.6 The Blood Vessels 3.7 The Heart
3.9 Heartbeat and Cardiac Output 3.10 Heart Arrhythmia
3.11 What is Blood Pressure ? 3.12 How is Blood Pressure Measured ?
3.14 The Role of Lymphatic System ? 3.16 What is a Pacemaker ?
3.17 How does Blood Clot ?
4. THE RESPIRATORY SYSTEM
4.1 What is Respiratory System ? 4.2 Oral and Nasal Cavities
4.3 The Epiglottis 4.4 The Lungs
4.5 Breathing
5. THE IMMUNE SYSTEM
5.1 What is Immune System ? 5.2 Immune System Categories
5.3 Immune System & Natural Environment 5.4 Immune System and Diet
5.5 The Thymus Gland 5.6 White Blood Cells
5.8 Immune System Soldiers 5.10 The Lymph Nodes and Lymph Glands
5.11 The Spleen and Tonsils 5.12 Stress and the Immune System
5.13 What is Fever ? 5.14 What is Pus ?
6. THE METABOLIC SYSTEM
6.1 What is Metabolism ? 6.4 How to Improve Metabolism ?
7. THE DIGESTIVE SYSTEM
7.1 What is Digestive System ? 7.2 The Digestive Tract (Alimentary Canal)
7.3 The Mouth (Pharynx) and Saliva 7.5 The Stomach
7.6 The Intestines 7.7 The Small Intestine
7.9 The Large Intestine (Colon) 7.10 The Pancreas, Liver and Gall Bladder
7.11 The Oesophagus (Foodpipe) 7.12 Indigestion (Dyspepsia) & its Complications
7.15 Some Common Disorders of the Digestive System
8. THE EXCRETORY SYSTEM
8.1 What is Excretory System ? 8.2 The Kidneys and Urinary Tract
8.4 Urine Formation 8.5 Disorders of the Urinary System
8.7 How do People Control when They Urinate ?
9. THE MUSCULAR SYSTEM
9.1 What is Muscular System ? 9.2 Skeletal Muscles
9.3 Smooth and Cardiac Muscles 9.4 Muscle Action
9.5 Common Muscle Problems 9.6 Why does Muscular Fatigue develop ?
9.7 Why does Weight Training make a Person look Muscular ?
9.8 What dose it mean if a Person has Temporomandibular Joint Syndrome(TMJ)?
10. THE SKELETAL SYSTEM
10.1 What is Skeletal System ? 10.2 The Skeleton
10.3 Number of Bones 10.4 Composition of Bones
10.5 Bone Marrow 10.6 Bone Growth
10.8 Cartilage 10.9 Ligaments and Tendons
10.10 The Pelvis 10.11 Joints
10.12 The Spine 10.13 Common Bone Diseases
11. THE REPRODUCTIVE SYSTEM
11.1 What is Female Reproductive System ? 11.5 What is Male Reproductive System ?
11.9 How does a New Life Begin ? 11.10 Fertilisation
11.13 Fertilisation to Baby 11.19 The Birth
11.20 An Infant 11.21 The Baby and the Adult
11.22 What makes You Grow ? 11.23 Resemblance
11.24 Disorders of the Reproductive System
1. tHE ENDOCRINE SYSTEM
What is Endocrine System?
1.1 All activities such as eating, crying or walking, have one thing in common – they all involve the work of glands. Your endocrine system is composed of specialised tissues or organs called endocrine glands that produce or secrete various chemicals. Unlike other glands, the endocrine glands do not have ducts (tubes) that deliver their secretions to a particular point. Instead, they secrete chemical substance called hormones directly into the bloodstream. The main endocrine glands are the thyroid, the pituitary, the adrenals, the endocrine cells in the pancreas, and the reproductive organs. Hormones are also produced by the hypothalamus of the brain, the pineal gland, the parathyroid glands, the thymus and the walls of the stomach and the intestines.
The Hormones
1.2 A hormone is a chemical substance which is produced within the body. Hormones serve as a means of communication among the various parts of the body to help them function in a proper way. The hormones control such body activities as growth, development and reproduction and regulate a variety of body functions including the way the body uses food and the reaction of the body to emergencies. Healthy blood contains fairly exact levels of several other chemical substances. Hormones regulate the levels of these other chemicals in the blood for us to remain healthy.
The Hypothalamus
1.3 Hypothalamus is a small area at the base of the brain. It plays a key role in regulating the body’s general level of activity. In addition to other functions, it controls the pituitary gland, the so-called “master gland” of the body’s endocrine system. Certain parts of the hypothalamus regulate body temperature, breathing, sleep, hunger, thirst, urination and emotions. Other parts produce hormones which control the secretion of individual pituitary hormones. The pituitary hormones, in turn, affect many of the body’s endocrine glands. These glands secrete hormones that influence growth, sexual development, and the rate at which the body changes food into energy and living tissue. The hypothalamus produces other hormones which are stored in and released by the pituitary gland. One of these hormones reduces the amount of water lost from the body in urine.
The Central Nervous System
1.4 Hormones act as chemical messengers and regulate many body functions. Each hormone carries a particular message to specific cells of the body. The central nervous system regulates the secretion of these hormones.
1.5 In fact the Central Nervous System and the Endocrine System are so closely linked that they are sometimes called the Neuroendocrine System. Coordinating centres in the hypothalamus regulate the activities of these two systems. The hypothalamus is sometimes called the “master switch” of the endocrine system because most endocrine glands, including the pituitary “master gland”, are either directly or indirectly under its control. The hypothalamus constantly monitors the internal state of the body and sends out messages that keep body functions stable. Sometimes, the messages are in the form of nerve impulses; at other times, they are hormonal. Nerve impulses produce rapid changes, while the release of hormones causes slower but long-lasting effects.
The Pituitary Gland
1.6 The pea-sized important pituitary gland lies at the base of the brain near the centre of the skull and is connected to the hypothalamus by a slender stalk. Hormones produced by the hypothalamus move through the pituitary gland. In response to these hormones, the pituitary gland produces at least six hormones of its own which regulate growth and direct the reproductive organs, the adrenal glands and the thyroid gland. In women, pituitary hormones stimulate uterine contractions during childbirth and release of breast milk during nursing.
1.7 Dwarfism and Gigantism – The hormones produced by the pituitary gland, in association with other hormones during childhood and adolescence, promote growth and development of bones and the body’s building blocks called “proteins”. An untreated genetic deficiency of these growth hormones causes a marked slowing of growth, resulting in “dwarfism”. Over-secretion on the other hand can lead to a condition of over-growth called “gigantism”. Both these people may be perfectly proportioned and intelligent too.
The Thyroid Gland
1.8 The butterfly-shaped thyroid gland, weighing less than 28 grams, is located at the base of the front of the neck on both sides of the windpipe and below your Adam’s apple. Thyroid takes iodine from the blood and uses it to make hormones. It secretes hormones that play a crucial role in determining the speed at which the body transforms food into energy (metabolic rate) and the speed at which the body uses that energy. One thyroid hormone is responsible for normal growth of the brain, bones and muscles during childhood. The thyroid gland also helps maintain a normal heart rate, has a role in maintaining the body’s calcium level, and affects reproductive functions. The failure of the pituitary gland to secrete the hormone that stimulates the thyroid can cause hypothyroidism in which one usually gains weight. On the other hand, the release of too many hormones than required by the body causes hyperthyroidism which increases the appetite but still one loses weight.
The Adrenal Glands
1.9 There is an adrenal gland located on top of each kidney. These glands produce dozens of different hormones. The adrenal’s inner layer secretes hormones that cause a “fight-or-flight” response to stressful situations. The outer layer secretes hormones that help regulate the body’s metabolism and its salt-and-water balance and control inflammation.
1.10 Fight-or-Flight Response – In response to stressful situations the adrenals release hormones into the bloodstream. The concentration of “adrenaline” increases when you are afraid and the concentration of “noradrenaline” increases when you feel aggressive. In these situations the heart steps up its activity, providing more blood for the brain and muscles, breathing gets faster and deeper, providing more oxygen, and perspiration is increased, resulting in the cooling of the body. Many muscles of the body tighten to prepare the body for rapid and vigorous action. Functions such as eating and digesting are postponed to conserve energy. In these ways all the forces of the body are prepared either to attack an enemy or flee to safety.
The Pancreas
1.11 The pancreas, a pinkish-yellow gland about 15 cm long lies crosswise behind the stomach. Its main function is to produce digestive juices to breakdown food. It also produces two hormones (insulin and glucagon) needed to regulate the blood glucose level and metabolism. The first part of the small intestines, the duodenum, loops round the pancreas. Digestive juices produced by the pancreas flow through an opening into the duodenum. These digestive juices have water and salt that aid digestion and decrease the effect of stomach acids. The substances in the digestive juices help in breaking down proteins, carbohydrates and fats. The clusters of cells scattered throughout the pancreas secrete hormones and send them directly into the bloodstream. Insulin hormone produced by these cells travels through the blood stream to cells throughout the body. Insulin helps cells to take in and use glucose from the blood for energy – thus stablising the blood glucose level. The other hormone, glucagon, has the opposite effect to insulin i.e. it increases glucose production. If there is an imbalance in the amount of these two hormones in the blood, either too high or too low sugar levels will result.
1.12 Diabetes – It is a metabolic disorder of the chemical reactions that are necessary for proper utilisation of food along with inadequate or lack of insulin. Normally, pancreas release insulin proportional to the amount of food you eat. The beta cells in the pancreas monitor blood glucose levels regularly and release the amount of insulin necessary to use the glucose in the blood. Excess glucose is stored in the liver and muscles as glycogen (reserve energy). In between meals, when the cells need energy, glycogen is converted back into glucose and used by the cells. Excess glucose reaches the adipose tissue and is converted into triglycerides which is stored in the form of fat leading to obesity. Broadly there are two types of diabetes – Type I Diabetes (Insulin Dependent Diabetes Mellitus (IDDM) results if your pancreas cannot make enough insulin to help glucose get inside your cells for providing energy. Type I diabetes is also called Juvenile Onset Diabetes because people develop Type I when they are children or teenagers. Type II Diabetes (Non-Insulin Dependent Diabetes Mellitus (NIDDM) results because the cells in the muscles, liver and fat are unable to use insulin properly. In TypeII the body does not produce enough insulin or what it does produce is defective and does not work properly or the cells ignore the insulin. Type II diabetes is usually associated with lifestyle disorders such as bad diet, sedentary lifestyle and lack of exercise leading to obesity. 90% of diabetics have Type II diabetes and 10% have Type I diabetes. Lifestyle changes, dietary regulation, exercise and regular monitoring can help control or avoid the onset of diabetes.
The Pineal Gland
1.13 The pineal gland is a tiny organ lying in the centre of the brain and is thought to control body’s internal biological clock. The pineal gland produces a hormone whose production varies with periods of light and darkness in the surroundings. It obtains information about light in the environment by means of nerve pathways originating in the retina and other parts of the brain. Darkness stimulates the pineal gland’s production of the hormone. Therefore, the gland tends to secrete only small amounts of the hormone during the day and large amounts at night. Pineal gland also secretes a hormone that plays an important role in a person’s sexual development.
1.14 Biological Clocks – Biological clocks are systems built within the human body. The body machine follows a 24-hour cycle, coinciding with the rising and setting of the sun. Heartbeat, blood pressure and temperature, which are under the influence of hormones, are regulated by the daily cycles of the biological clocks. The most obvious daily cycle is sleep, during which the heart rate, blood pressure and temperature fall.
The Thymus
1.15 The thymus is a flat, pinkish-grey organ that plays an important part in the immune system of the body. It is located high in the upper chest cavity behind the breastbone and extends into the lower neck below the thyroid gland. When a person is born, the thymus is just about 15 grams. By the age of 12 it grows to about twice its original size, but by adulthood, the organ shrinks so much that it may be hard to distinguish it from the fatty tissue that surrounds it. The thymus helps in the development of white blood cells in the bone marrow. White blood cells help the body to fight/defend infection and disease. White blood cells are involved in the production of antibodies, in recognising and destroying specific types of cells and also in remembering a specific pathogen (a disease causing microorganism) in case it is encountered again.
1.16 Some of the white blood cells are changed into T-cells in the thymus to inhabit the blood, lymph nodes and spleen. These T-cells attack bacteria, viruses, cancer cells and various other harmful microorganisms. T-cells are sometimes called “killer cells” because of their ability to find and destroy such organisms.
The Parathyroid Gland
1.17 The parathyroid gland consists of four tiny glands that function as one gland. These glands lie in the front of the neck, close to the thyroid gland. The hormone produced by the parathyroid gland raises the amount of calcium in the blood when it becomes low. It also helps in absorbing more calcium from the digestive tract. Calcium is necessary for a number of body functions including bone growth and muscle and nerve functions.
The Reproductive Organs
1.18 The “testes” in males and “ovaries” in females produce hormones that regulate the development of sex characteristics and initiate the production of reproductive cells.
2. THE NERVOUS System
What is Nervous System?
2.1 Your nervous system is made up of billions of special cells called neurons. The neurons have bundles of fibres called nerves. These nerves conduct messages rapidly throughout the body. Nerve impulses travel along nerve fibres at speeds of 1-90 meters per second. The pathways between neurons are called neural circuits. Your nervous system regulates and coordinates your body’s physical and mental activities in response to changes in the internal and external environment. The changes, called stimuli, initiate impulses in millions of sensory receptors spread throughout your body. The most familiar are the sense organs: the eyes, ears, nose, skin and tongue. In addition to these organs, there are other sensory receptors within the body and close to the surface of the skin. The receptors translate events in a person’s surroundings into nerve messages, which are known as impulses. The nervous system is broadly divided into three parts i.e. automatic nervous system, central nervous system and peripheral nervous system.
The Automatic Nervous System
2.2 This part, which is not under your control, regulates such automatic involuntary bodily processes as breathing and digestion. This part includes the lower brain and spinal cord.
The Central Nervous System
2.3 The brain and spinal cord make up the second part of the central nervous system. It acts as a switchboard that controls and coordinates the activities of the entire nervous system. The brain (about 1.4 kg) is the organ responsible for thought, memory, consciousness, creativity and emotion. It also receives sensory impulses, controls and coordinates muscular movements, and regulates vital body processes. The spinal cord is the pathway for sensory and motor nerve impulses traveling to and from the brain. It also processes some information without the aid of the brain, as demonstrated by reflexes such as the withdrawal reflex. Cerebrospinal fluid fills the open spaces in the brain and surrounds the spinal cord. This fluid acts as a shock absorber, protecting the brain and spinal cord from damage. It transports metabolic wastes out of the central nervous system. Nutrients, hormones, and other vital substances are transported throughout the central nervous system by the cerebrospinal fluid.
The Peripheral Nervous System
2.4 The 31 pairs of spinal nerves as well as all the other nerves and nerve cells outside of the central nervous system make up the third part of the nervous system. This system carries nerve impulses to and from the body’s sensory cells and the central nervous system. The central nervous system analyses the information it receives from the peripheral nervous system and responds to it. The motor neurons of the peripheral nervous system carry out the instructions received from the central nervous system. It acts as a switchboard that controls and coordinates the activities of the entire nervous system.
The Nervous Tissue
2.5 The tissue of the nervous system is composed of two basic types of cells, neurons and glia (glial cells). A neuron consists of a cell body; dendrites, branched structures that conduct impulses to the cell body; and an axon, a long fibre that transmits impulses away from the body. There are three types of neurons. Sensory neurons send signals from the sense organs to the spinal cord and the brain. Motor neurons send signals from the brain and the spinal cord to the body’s muscles. Association neurons link sensory neurons to motor neurons. Glial cells help support and nourish neurons and account for approximately one-half of the volume of the nervous tissue. There are four types of glial cells, each with a different function.
The Neurotransmitters
2.6 Neurons are separated from each other and from other body cells by a tiny gap called a synapse. When a nerve impulse reaches a synapse, the axon releases a chemical called a neurotransmitter. The neurotransmitter transfers the impulse across the synapse to the target cell. Then, the synapse is cleared so that another impulse can cross. Over 60 different chemicals have been identified either as neurotransmitters or as substances that modify the activity of neurotransmitters.
2.7 Neurotransmitters and Drugs – The use of psychoactive drugs alters the transmission of nerve impulses. For example, caffeine stimulates the nervous system by facilitating synaptic transmission. Cocaine, amphetamines, and some antidepressant drugs cause substances to remain in the synapse longer. The result is prolonged stimulation of the nervous system. Some psychoactive drugs are addictive. The body adjusts to the changes these drugs cause. If the drug is withdrawn, the body will be unable to function as it had previously. The addicted drug user will then experience withdrawal symptoms.
The Brain
2.8 The brain weighing about 1.4 kg contains about 1 trillion cells, and it consists of three basic parts: the cerebrum, the cerebellum and the brain stem. The cerebrum, which is the largest part of the brain, initiates all the body’s voluntary actions. The cerebellum controls balance of the muscle movement. The brain stem, which connects the cerebrum to the spinal cord, has nerve centres that regulate swallowing, the digestive process, circulation and respiration.
2.9 Cerebral Hemispheres – The cerebrum is made up of a right hemisphere and a left hemisphere, each divided into four lobes. Each hemisphere controls the actions of the opposite side of the body. In most people, the left hemisphere is dominant. In general, the left hemisphere is responsible for speech, writing, and reading. It also plays a major role in verbal, analytical, and computational skills. The right hemisphere is more involved with nonverbal functions, such as emotion, intuition, awareness and interpretation of space and connected by a structure called the corpus callosum, and there is constant communication between the two sides.
2.10 Blood-Brain Barrier – Some substances taken into the body can interfere with the proper functioning of the brain. Fortunately, a structure called the blood-brain barrier prevents most harmful substances from passing from the capillaries of the brain into the cerebrospinal fluid. The cells lining the brain’s blood vessels are tightly joined together and play the primary role in forming the blood-brain barrier. In addition, projections from one type of glial cells cover the outside of the brain’s blood vessels, making passage into the brain even more difficult. A special carrier system allows water, oxygen, carbon-dioxide, glucose and nutrients to pass through the blood-brain barrier.
Disorders of the Nervous System
2.11 Stroke – When the blood supply to the brain is cut off, a stroke occurs. Most strokes occur due to damage to the blood vessels, caused by high blood pressure. Nerve cells in the affected areas die, and the victim may lose the ability to carry out functions contolled by those areas of the brain such as speaking or moving a limb. A common disorder due to a stroke is the paralysis of one side of the body.
2.12 Tumours – Tumours are abnormal growths that can cause severe brain damage. The real cause of a brain tumour is not known. The extent of the damage depends on its size and location. The brain cells surrounding the tumour are destroyed by the tumour’s constant growth. As the tumour grows, it also creates pressure which may damage other areas of the brain, or interfere with other normal functions of the brain.
2.13 Epilepsy – This is a disease that causes a person to fall unconscious. It is often accompanied by violent uncontrolled movements of the body. Our brain cells produce some electrical energy which travels through our nervous system and activates the muscles. When the brain of a patient is not able to limit or control the production of electrical energy, epileptic seizures occur. Fatigue and emotional stress can enhance the occurrence of epileptic seizures.
2.14 Mental Illness – Any disease of the mind that affects a person’s thoughts, feelings or behaviour is a mental illness. These illnesses lead to unhappiness and socially unacceptable behaviour. Some mental illnesses may occur from a physical cause, such as a birth defect, a disease, or an injury to the brain. Certain conditions in the environment also affect a person’s mental state. The imbalance of certain brain chemicals may cause mental illnesses. Sometimes it is hereditary.
2.15 Encephalitis – This is an inflammation of the brain. In most cases encephalitis results from a virus infection. Bacteria, harmful chemical, and various tiny parasites can also cause the disease.
2.16 Meningitis – This is a disease that affects the membranes covering the brain and spinal cord. People of all ages can become victims of this disease, but it most frequently strikes infants and children. Meningitis results from infection by bacteria, viruses, fungi or other microbes. Physically weak or unhealthy people are more prone to this disease.
Genetic Disorders
2.17 Our genes (the hereditary materials in cells) carry instructions for the development of the brain. These instructions are extremely complex and so errors occasionally occur. Errors in the instructional material can lead to serious defects, like mental retardness in the structure and functioning of the brain.
Concussion
2.18 When the head receives a violent blow – such as from a fall – the brain is jarred. The force of the blow hitting the skull interferes with normal brain function and is called a concussion. If the force is mild, loss of consciousness may occur but will usually last only a few seconds. However, if the force is intense, loss of consciousness may be prolonged and damage may be extensive. It is common for a person to experience confusion or even amnesia following a concussion. Although the damage may not be obvious from the outside, concussions can be very dangerous.
The Spinal Cord
2.19 The spinal cord is a cable of nerve tissue that extends from the base of the brain to just below the level of the ribs. In adults, it is about the thickness of the little finger. The spinal cord is surrounded by the spinal column (backbone), which protects it. Thirtyone pairs of spinal nerves connect the spinal cord with the rest of the body. The spinal nerves are composed of millions of both sensory neurons and motor neurons. These neurons transfer millions of messages or impulses between the body and the brain.
2.20 Spinal Cord Injuries – Spinal cord injuries are relatively common. About 45 percent of all spinal cord injuries are incurred in motor vehicle accidents. Injuries to the spinal cord can alter or prevent communication between the brain and the body. If the injury is serious enough, paralysis can occur. In general, the higher up on the spinal cord the injury is, the more severe the damage will be. Damage to the spinal cord in the neck can result in paralysis from the neck down, while injuries lower on the spinal cord may produce paralysis only in the legs.
Reflexes
2.21 Reflexes are involuntary responses to stimuli and are not controlled by the brain. Reflex movements take only a split second to occur. For example, when a person touches a hot stove, a nerve impulse travels through a sensory neuron in the person’s hand to the spinal cord. There, it is transferred first to an association neuron and then to a motor neuron traveling quickly back to the hand. In a split second, the withdrawal reflex pulls the hand away from the stove. If this message had to go through the brain, the response time would be longer increasing the possibility of injury.
Sensory Receptors and Sense Organs
2.22 Your senses are the window through which you view the world around you. They allow you to interpret changes in your internal and external environment. One day you may feel well, the next day you may have a headache. Your senses are what provide this information to the brain, which in turn, interprets it. Not everyone interprets information in the same way cord. That is why some people love hot chili peppers, while others prefer more subtle flavorings.
2.23 Internal Sensory Receptors – Sense receptors located deep within the body enable a person to feel internal pain, hunger, thirst, tiredness, and nausea. Other receptors located in skeletal muscles, tendons, and the connective tissue surrounding joints are sensitive to changes in stretch and tension. They continuously relay information about body position, equilibrium and movement to the central nervous system, and together they make up what is called the kinesthetic sense. Many internal sensations are not recognised at a conscious level. For example, some sensors monitor blood pressure; the information they send to the brain is not processed by the cerebrum, so an individual is not aware of this sensation.
2.24 Sensation and the Skin – Touch is the sensation produced by pressure on the surface of the body and is sometimes called the tactile sense. Pressure receptors are located all over the skin. On sensitive parts of the body, such as the tongue, lips and finger pads, their concentration is very high. Touch messages are transmitted by bundles of sensory nerve fibres that come through the subcutaneous layer to the dermis, or inner layer of skin. The bundle of fibres, some of which reach into the epidermis, or outer layer of the skin. These nerve endings in the epidermis are sensitive to pressure. Other sensory nerve fibres end in specialised receptors in the dermis, which sense temperature or pain.
Smell and Taste
2.25 Your sense of taste and your sense of smell are both stimulated by chemicals. Their main purposes are to help you detect harmful substances and to stimulate your appetite and digestion. Even though taste and smell messages travel separately to different regions of the brain, they create a combined feeling of either pleasure or displeasure when you are eating. For example, think of how the aroma of a delicious meal can make your mouth water.
2.26 Smell – Olfactory (smell) receptors are located in a dime-sized area in the roof of the nasal passages. They are able to sense minute amounts of chemicals in the air. These receptors are actually specialised neurons whose dendrites are modified into hair-like projections called cilia. Their axons transmit nerve impulses through an opening in the skull directly to the olfactory bulb in the forebrain. When a person has a stopped-up nose, little air passes over the olfactory receptor cells, resulting in a diminished sense of smell. Compared to some other mammals, humans have a poor sense of smell. For example, humans have anywhere from 5 million to 20 million olfactory receptors, while dogs have 40 million or more.
2.27 Taste – The tongue is covered with small, rough bumps called papillae. Each papilla is covered with taste buds, clusters of taste sensors. Taste receptors sense chemicals – classified as sweet, sour, salty, or bitter – in foods and beverages. When chewed-up food mixed with saliva washes across the papillae, the chemicals in the food stimulate the taste receptors. The receptors transmit nerve impulses to the brain through the gustatory nerve, and the brain interprets the taste. Babies have about 10,000 taste buds, but this number decreases as a person gets older. There are other reasons why the ability to taste can diminish. For example, there is good evidence that long-term cigarette smoking damages taste receptors, adding to the loss that normally comes with age.
The Vision
2.28 Human beings have excellent eyesight. In fact, only birds can see better than humans can, although squids and octopuses can see just as well. Your vision is a response to light falling on the retina of the eye. Light rays enter your eye through the pupil and are focused onto the retina, which is actually an extension of your brain. Nerve fibres of the retina join to form the optic nerve, which transmits nerve impulses to the occipital lobe of your brain. Your brain then interprets these impulses as an image, and you “see” it.
2.29 Eye – The outer surface of the eye is covered by the cornea, a transparent membrane that protects the eye but allows light to enter. Behind the cornea is the iris, a thin, coloured, circular membrane. In the centre of the iris is an opening called the pupil. Muscles in the iris control the amount of light that is let in by altering the diameter of the pupil. The pupil dilates, or enlarges, to let more light in and contracts to let in less light. Behind the pupil is the lens, a thick, curved structure that focuses the light rays so that they will fall on the retina, the thin lining on the back of the eye. The image on the retina is inverted.
30. Receptor Cells – There are approximately 1 billion receptor cells in the retina. Rods are cells that are extremely sensitive to light; however, they cannot detect colour, and they produce poorly defined images. Cones are cells that detect colour and produce sharp images. At the centre of the retina is a concentration of about 3 million cone cells. People usually move their eyes so that the light rays from an object they want to see fall on this area. There are no cones or rods at the point where the optic nerve enters the retina. Light that falls on this area does not stimulate any sight receptors, resulting in a “blind spot” in the field of vision.
Eye Disorders
2.31 Image Forming – When the eyes view an image, each eye sees the image from a slightly different angle. About one-third of the visual fields overlap, but the other two-thirds differ. This overlap produces binocular vision, which enables people to perceive depth. Also, the optic nerves do not connect to only one hemisphere. About one-half of each optic nerve crosses over into the opposite side of the brain; because of this, each hemisphere receives visual information from both eyes. The brain combines all the information it receives to produce one image.
2.32 Where do tears come from and what is their purpose? – Tears are produced by a gland found above and to the outside of each eyeball. Each gland produces a watery secretion that mixes with a slightly oily secretion from accessory glands. The tear glands have between 10 and 12 ducts, and every time the eyes blink, tears are spread across the surface of the eye. Tears protect the eyes by lubricating them and washing away debris. Also, they contain an enzyme that helps prevent eye infection. Tears drain into two ducts in the inner corners of the eye. These ducts drain into the back of the nose.
2.33 Nearsight, Farsight and Astigmatism – Some people are nearsighted or farsighted; others have astigmatism. Why is this? For an image to appear clear, the lens must focus light rays directly onto the retina. The lens does this by using tiny muscles and ligaments to adjust its thickness. If the shape of the eyeball is too elongated or too short, the lens will be unable to change sufficiently to focus the image properly. In nearsighted people, the focal point is in front of the retina, resulting in poor distance vision. In farsighted people, the focal point is behind the retina, resulting in poor close vision. Astigmatism is caused by an irregularly shaped cornea. This causes the light rays to be focused erratically and to mostly miss the retina. Corrective lenses adjust the light ray’s focal point so that it is on the retina.
2.34 Colour Blindness – A condition that is almost always genetic in origin, is the inability to distinguish colours. It is caused by an abnormality of one or more of the three types of light-sensitive pigments in the cone cells. The inability to distinguish red light from green light is the most common type of colour blindness. About 10 percent of all males have some degree of colour blindness while less than 1 percent of females are affected. Total colour blindness is extremely rare.
2.35 Cataracts – When a person has cataracts, the lens of the eye is no longer transparent. Light cannot pass through the lens easily, so vision is diminished. Although ageing is the most common cause of cataracts, they can also result from a reaction to a drug, from radiation including solar exposure, and from disease. In the past, people with cataracts became blind; however, today the condition can be corrected surgically. The faulty lens is removed and replaced with an artificial one. Glasses or contact lenses are then prescribed to adjust the vision.
2.36 Cornea Scar – Some diseases cause scarring of the cornea. When this occurs, blindness may result because light cannot pass through the damaged cornea. This condition can be corrected by a corneal transplant. The central portion of the scarred cornea is removed and replaced with a cornea from an organ donor.
Hearing and Equilibrium
2.37 When you think of your ears, you may only consider your external ear, the part that sticks out on each side of your head. But you also have a middle ear and an inner ear, the portions responsible for sensing sound.
2.38 Hearing – The external ear funnels sounds through the ear canal to the eardrum. On the other side of the eardrum is an air-filled cavity called the middle ear. This part of the ear opens to the back of the throat through a tube called the eustacian tube. As sound waves apply pressure to the eardrum, the eardrum vibrates. Three bones located in the middle ear – the hammer, the anvil, and the stirrup – transfer this vibration to a fluid-filled chamber, the cochlea. Inside are tiny hair cells that serve as sound receptors. They respond to the vibrations and send impulses to the brain, which interprets the vibrations as sound.
2.39 Equilibrium – The two other portions of the inner ear, the semicircular canals and the vestibule, are involved with the sense of equilibrium. The semicircular canals detect movement of the head. The vestibule contains sensory cells that respond to changes in head position with respect to gravity. It is the inner ear that contains the sense cells, which enable you to hear, and that produces your sense of equilibrium, or balance and stability in space.
2.40 Hearing Loss – Certain conditions, diseases, and types of trauma can result in hearing loss. For example, a build up of wax in the ear or an ear infection can create a barrier to sound waves entering the ear, preventing vibration of the ear drum and the inner-ear bones. Repeated inner-ear infections can result in scarring of the eardrum and damage to the bones of the inner ear. If this occurred, sound waves would not be conducted as well and hearing would be diminished. This type of hearing loss is referred to as conductive deafness.
2.41 Repeated exposure to excessively loud sounds will destroy the tiny hair cells in the cochlea, resulting in hearing loss. Once destroyed, these hair cells can never be replaced. Rock concerts and exposure to other loud noises, such as power saws cause this type of hearing loss. Wearing ear plugs protects the ears from this type of damage. There is now evidence that prolonged exposure to even moderately loud sounds, such as head phones, has a cumulative effect and can cause hearing loss classified as nerve deafness.
2.42 Where does earwax come from? – Sebaceous glands and ceruminous glands, specialised sweat glands, located in the ear canal produce this wax-like secretion. Earwax, called cerumen, protects the ear from infection and traps debris or small insects that enter the ear. It also helps prevent the ear drum from drying out. Usually the wax moves outward, moving anything it trapped along with it.
3. THE Circulatory System
What is Circulatory System?
3.1. Your circulatory system includes the cardiovascular system and the lymphatic system. The cardiovascular system, which consists of the heart (cardio), blood, and blood vessels (-vascular), transports life-giving blood carrying oxygen, nutrients, antibodies, and infection-fighting cells to each cell in your body. It also helps rid the body of wastes. In addition to blood, your body has fluid lymph that circulates throughout it. The lymphatic system is a drainage subsystem for the larger circulatory system and is active in fighting disease.
Composition of Blood
3.2. Blood consists of various specialised cells and a fluid called plasma. The yellowish plasma contains water, nutrients, wastes, and other materials. The cells found in blood include red blood cells, which carry oxygen; white blood cells, which protect the body against disease; and platelets, which initiate the process of blood clotting. Blood cells are made in the marrow, a soft fatty substance that fills the hollow parts of bones.
3.3 Red Blood Cells – These consist mainly of haemoglobin, an oxygen-carrying protein that gives them their red colour. Oxygen is picked up by the red blood cells in the lungs. As blood is pumped around the body, oxygen is dropped off wherever it is needed by other body cells and tissues.
3.4 White Blood Cells – White blood cells, fewer than red, are an integral component of the immune system and help defend the body against infection and disease. White cells help in destroying most of the harmful microorganisms (germs) that enter the body and help us to stay strong and healthy. Some cannot be destroyed as they carry poison. To make the poison-carrying germs harmless, the white cells produce an anti-toxin (anti-poison) which turns the poison harmless.
3.5 Platelets – Platelets are a round or oval disc-like structures 2-4 mm in diameter in the blood ranging from 1,50,000 to 4,50,000/ul and play an important role in coagulation (clotting) that helps stop bleeding. They live for about 8-10 days only.
The Blood Vessels
3.6 The 1,00,000 km blood vessels of the circulatory system form a continuous system supplying oxygenated blood to the body’s 100 trillion cells, tissues and organs. There are three types of blood vessels. Arteries are the thick-walled vessels that carry blood from the heart to all parts of the body. Veins, which have thinner walls, carry blood back to the heart from all parts of the body. Veins also contain tiny valves that prevent blood from flowing downward from the pull of gravity. Capillaries, which are the smallest of the blood vessels, link the arteries to the veins. The wall of a capillary is only one cell thick, which allows oxygen and nutrients to leave the bloodstream easily and be taken up by the body’s cells. Because of their small diameter, blood cells must pass through capillaries in single file. No cell in the body is more than a few cells away from a capillary.
The Heart
3.7 A fist-size human heart weighing about 340 grams, is the world’s most efficient and wonderous pump, pumping blood through more than 1,00,000 kilometers of blood vessels (arteries, veins and capillaries). The heart lies in the middle of the chest between the lungs. It is situated closer to the front of the chest than to the back and slightly to the left side. The power of the heart is less than a 100 watt bulb but has incredible efficiency of pumping nearly 7,600 litres of blood per day, equivalent to filling tanks of 300 cars; and that too without rest and break and year after year. Heart is made up of a special muscle consisting of several layers of muscles arranged in circles and spirals. Cardiac muscle is called involuntary because it works without our thinking about it. No other muscle in the body is as hardworking and as strong as the heart is. Heart is only 0.5% of body weight but needs 5% of total blood supply to take care of body’s nutritional needs. The work done by the heart is almost equal to the work we would perform if we had to lift about 4.50 kilograms weight 3 feet of the ground and if we had to repeat this task twice every minute for our entire lives. The heart is the circulatory system’s pump. Actually, the heart is two pumps placed side-by-side. The septum, a muscular wall divides the right and left sides of the heart. It prevents the blood from crossing over from one side to the other. The right side of the heart pumps blood to the lungs, and the left side pumps blood to the rest of the body. The atria receive blood and pump it into the ventricles. The ventricles push the blood out of the heart. The ventricles’ job requires a greater force, so the ventricles are larger and more muscular. Valves in the heart allow blood to move through it in one direction only.
3.8 Blood enters the right atrium of the heart and is pumped into the right ventricle. When the right ventricle contracts, blood is pumped through the pulmonary arteries to the lungs, where the blood gives off carbon dioxide and picks up oxygen. Oxygen-rich blood returns to the heart through the pulmonary veins and the left atrium. It is, then pumped to the left ventricle. The left ventricle contracts, pumping blood into the large artery, aorta, and out to various parts of the body. Oxygen-rich blood is carried by the branches of the aorta to cells in all parts of the body. When the cells use up all the oxygen, the veins carry the blood back to the heart. The arteries coming out of the right side of the heart carry this blood to the lungs, where it gets more oxygen. Then the oxygen-rich blood is carried to the left side of the heart, and the cycle begins all over again. Blood that does not get oxygen is purplish-red in colour. Blood that is rich in oxygen is scarlet or bright red in colour.
Heartbeat and Cardiac Output
3.9 One complete contraction and relaxation of the heart muscle makes up one heartbeat. In an adult the heart beat rate is 60-80 times a minute. In children, it is faster – about 80-100 times. In babies, it is very fast. Exercise, fever, excitements and some kinds of infections increase the rate of heartbeat. During exercise, the muscles and the body organs need more oxygen and nutrients. The heart accommodates this need in two ways. First, it pumps blood out faster, increasing the heart rate. Second, the heart increases its stroke volume, the amount of blood pumped out of the heart
with each heartbeat. The amount of blood pumped with each beat multiplied by the number of beats per minute is called cardiac output. As a person exercises regularly and becomes more conditioned, the heart begins to work more efficiently and stroke volume increases. In very well-conditioned athletes, the heart itself enlarges in response to the increased demand. This type of enlargement is not harmful and disappears rapidly if the exercise level diminishes.
Heart Arrhythmia
3.10 The heart beats in a regular rhythm as the walls of the atria and ventricles alternately contract and relax. This is called the cardiac cycle. If the cardiac cycle is disrupted and the heart gets out of rhythm, a condition called arrhythmia results. Arrhythmia can lead to serious consequences, including death. When a person begins to exercise, the heart adjusts to the greater demand for oxygen by increasing its rate. If the person exercising has a heart problem or is in a weakened condition, there is a chance that as the heart rate increases, the heart will get out of rhythm. When the heart’s atria get out of synch, a person can survive because blood is still able to move through the heart. However, if the ventricles are affected, sudden death may occur because blood does not get pumped to the vital organs. To help avoid exercise-related heart-rhythm problems, always warm up first so the heart can adjust slowly. There are other causes for arrhythmia. For example, the drug cocaine can cause arrhythmia by disabling the nerves that regulate the contractions of the heart.
What is Blood Pressure?
3.11 Blood pressure (BP) is determined by two key factors: how hard heart beats and how easily the blood flows through the arteries. The force exerted by the heart as it pumps blood into the arteries creates a pressure within them and this is called “blood pressure”. A certain level of blood pressure is thus essential to keep the blood circulating in the body. But when pressure becomes too high, it is called hypertension which is caused by constriction or narrowing of the small blood vessels.
How is Blood Pressure Measured?
3.12 The blood pressure has been traditionally measured in two figures with an instrument called “sphygmomanometer” in millimeter height of mercury rise (mmHg). Blood pressure is the result of two forces; (i) force from the heart as it beats and pumps blood into the arteries and throughout the circulatory system and (ii) the force of the arteries as they resist blood flow between heart beats when the heart is at rest. Thus during each heart beat, the heart muscle contracts to push blood around the body. The pressure produced by the heart is the highest when it contracts to push the blood on its journey through the body and this is known as systolic (higher value) pressure and indicates the activity of the heart. Then the heart muscle relaxes before its next contraction, and the pressure is at its lowest, which is known as diastolic (lower value) pressure and shows the condition of blood vessels.
3.13 Both systolic and diastolic pressures are measured when you have your BP checked. For example, universally recognised normal BP of 120/80 represents 120 mmHg of systolic pressure and 80 mmHg of diastolic pressure. Systolic pressure range can be from 80 to 300 and diastolic from 60 to 140.
The Role of Lymphatic System
3.14 The cells of the body are bathed in a clear watery fluid called lymph. This fluid helps move materials between the capillaries and the body’s cells. Lymph is formed from water, proteins, and other nutrients that move out of the blood into the spaces between the body’s cells. This fluid must be returned to the circulatory system. A system of lymphatic vessels similar to the veins and capillaries collect the fluid and return it to the circulatory system. The lymph capillaries parallel the blood capillary system and are connected to larger lymph vessels that eventually connect to one of two ducts. These two ducts, the thoracic and the right lymphatic, open into two veins just above the heart.
3.15 The lymphatic system is also a part of the body’s immune system. In addition to the lymph fluid and vessels, this system includes the lymph glands, the thymus gland, the spleen and the tonsils. For information about the role of the lymphatic system in fighting disease, refer to the section on The Immune System.
What is a Pacemaker?
3.16 Two small groups of cells in the wall of the heart set the pace for cardiac contraction. They are the heart’s natural pacemaker. Sometimes disease causes these cells to become slow in their initiation of the contraction. If medication does not help, doctors can insert an electronic, artificial pacemaker near the heart. This pacemaker is battery-operated, and wires from it send a small electric impulse to the heart at regular intervals.
How does Blood Clot?
3.17 The body has a special way of mending itself. When a blood vessel is cut, platelets are triggered off to produce a clotting substance, which sticks to the edges of the cut. This joins with other clotting substances to form thread-like strands, which get tangled together, trapping blood cells between them. They then release chemicals which react with plasma proteins to form a blood clot. The blood makes a kind of crust, called a “scab” over the cut. The drying scab also keeps germs out of the body until the cut has healed. That is why we should never pick and remove a scab. After some time when the skin underneath has healed, the scab falls off by itself.
4. the Respiratory System
What is Respiratory System?
4.1 Out of different gases in the air only oxygen is important to life and the body. If the brain cells do not get enough oxygen even for a few minutes, they begin to die and the brain gets damaged and the heart stops beating. We live only when we take sufficient oxygen. Every breath we take provides essential oxygen to our body cells which produce the waste product carbon dioxide. The respiratory system includes the cone-shaped 13 cm long tube pharynx (throat), the larynx (voice box), the 13 cm long and about 2.5 cm dia tube trachea (windpipe) and the lungs.
Oral and Nasal Cavities
4.2 Normally, the air enters the body through the nostrils. Tiny hairs in the nose help filter out dust and dirt and thus protect us from many breathing problems. But when the nose is blocked, we can breathe through the oral cavity (mouth), which though is less healthier than through the nose. There are also very tiny hairs in the windpipe, which move like grass in the wind. These tiny hairs help in carrying the trapped debris in the mucus back to the throat, which can be discarded by coughing or swallowing. The cells in the nasal cavity warm and moisten the air before it enters the lungs. The cells lining the nasal cavity and the windpipe secrete a sticky liquid called mucus, which traps any dust, dirt, bacteria and viruses breathed in.
The Epiglottis
4.3 Both nasal and oral cavities meet at the throat. The air from the nose or mouth passes through the throat to the voice box where the vocal cords are located. The voice box is attached to the windpipe as well as the foodpipe. When a person swallows, the epiglottis (a special protective flap) closes the opening to the windpipe preventing foods or liquids from entering the lungs. But if by chance food enters the windpipe, it can be brought back to the throat by coughing and then swallowing properly.
The Lungs
4.4 A right and a left lung are located in the chest cavity. They have a spongy appearance resembling a plastic bag with lots of bubble like holes. The lungs are the only organ in the body that can float by themselves. Below the lungs is a sheet of large muscle tissue, the diaphragm, which separates the chest cavity from the abdominal cavity. It is the dome-shaped chief muscle in the respiratory process. The two tubes known as bronchi connect the windpipe to each lung. The bronchi are subdivided many times forming smaller and smaller passages, the smallest of which is known as bronchioles. At the end of each bronchiole is a cluster of tiny air sacs or pockets called the alveoli, which look like a bunch of grapes. Both lungs contain about 300 million alveoli with a large surface area. If all the alveoli could be spread flat, they would cover an area equal to the size of a tennis court. The walls of the alveoli are covered with tiny capillaries through which blood can easily pass into the blood stream. Oxygen passes from the alveoli into these capillaries for delivery to the body‘s cells. Simultaneously, carbon dioxide in the blood stream moves from the capillaries into the alveoli, where it is expelled from the lungs. This simultaneous exchange of the gases is called respiration. Some air always stays in the lungs. Otherwise the lungs would collapse.
Breathing
4.5 Air moves into and out of the lungs with every breath. When a person inhales, the dome-shaped diaphragm contracts, flattens and moves downwards, the rib muscles expand and enlarge the chest cavity upwards and outwards, oxygen-rich air rushes into the lungs, and the alveoli expand as they fill with air and lungs increase in size. When a person exhales, the diaphragm relaxes, becomes dome-shaped again and moves upwards and the rib muscles relax, the chest cavity becomes smaller, and carbon-dioxide-rich air is pushed out of the lungs, which become smaller. The muscles in the abdominal wall also contract to push the abdominal organs upwards against the diaphragm thereby aiding to push the air out of the lungs. This respiration process is automatic and is regulated by the respiratory control centre in the brain stem. In an adult the respiration rate is about 12-20 times a minute. Exercise increases the respiration speed, as our body cells are working hard and need more oxygen. Faster and deeper breathing allows oxygen to be pumped into the blood stream more swiftly from the lungs.
4.6 Why do People Yawn? — Even when people breathe normally, not all the alveoli are filled with oxygen-rich air. That means that some blood may pass through the lungs without getting sufficient oxygen. It is thought that this low blood-oxygen concentration triggers a yawn reflex. Yawning causes a person to take a deep breath, which makes more oxygen available to the alveoli and increases the blood-oxygen concentration.
5 tHE Immune SYSTEM
What is Immune System?
5.1 Immune system is the capability of the body to fight against any alien viral, bacterial, fungal or cellular attack. You constantly come in contact with many pathogens like bacteria and viruses that have the potential to make you ill. When the body’s non-specific defences are unable to overcome an invading organism, the body’s immune system goes to work. Rather than being an organ system, it works by using components of the lymphatic and circulatory systems. Nature has developed this highly complex and wonderous inborn defence mechanism to fight against any viral, fungal, bacterial or cellular attack. Nature has gifted the body to develop antibodies for shooting away or resisting infections by foreign bodies through this strong immune system.
Immune System Categories
5.2 The immune system can be broadly divided into three categories: –
(i) Innate or Natural Immunity – This is something that everyone is born with and is a general protection that human beings have. Innate immunity includes the external barrier – the skin – and mucous membranes (those that line the throat, nose and gastrointestinal tract) which are the first line of defence. If the outer defensive wall is broken, be it a cut or gash, the skin attempts to heal it quickly and special immune cells on the skin attack invading germs. Another form of natural immunity is “passive” or “borrowed” immunity. Despite being naturally present in the body, it traces its source outside the body. For example, antibodies (defensive proteins) present in mother’s milk provide an infant with temporary immunity to diseases that the mother had been exposed to. This can help protect the infant against infection during early years of childhood.
(ii) Adaptive or Acquired Immunity – This is something that individuals develop over the years. When our body gets infected, it induces antibodies on its own or sometimes with the help of medication and vaccination to fight the infection. It is most likely that the same infection will not recur. This is due to the memories these antibodies have. That is why if you have chicken pox in your childhood, chances are you will not get it when you are an adult. In other words, the antibodies induced during the first infection restart their fight if the same virus enters the body again. But then what about viruses that cause the regular cough, cold and fever? How do they recur inspite of having been cured by the antibodies before? That is because viruses are very smart! They tend to mutate and every time they enter the body, they do so in a somewhat new form. That stops the previous antibodies from recognising and fighting against them.
(iii) Artificial Immunity – This is similar to adaptive immunity, though of course, it is a little more permanent in nature. This immunity develops with the help of single or multiple vaccinations. Each dose develops a certain amount of antibodies in the system that help fight various infections and in due course create a permanent wall against them. Diseases like influenza, diphtheria and small pox fall in this category.
Immune System and Natural Environment
5.3 A person’s immunity level is much lower than normal when one is very young and when one is very old. In babies, it is yet to develop fully. In old people it stops developing and resistance power weakens. Also being over-protective and seriously limiting one’s exposure to natural surroundings leads to underdevelopment of immunity cells. The more a person is exposed to the natural environment, the more he develops his or her resistance power. Research reveals that children who are very active in outdoor activities are far more comfortable with their surroundings and have a stronger immune system than those who stay indoors all the time.
Immune System and Diet
5.4 Everyone’s immune system is different. Some people never seem to get infections, whereas others seem to be sick all the time. From genes to basic body metabolism, to lifestyle, to stress and most importantly to diet – all these have a cumulative effect on developing or debilitating the immune system as the case may be. But at the end of the day, it is the basics that matter. A good nourishing plant-based balanced diet, healthy lifestyle, regular exercise, stress management, and adequate relaxation and sleep are essential requisites for a fighting-fit immune system as well as a healthy disease-free body. Foods rich in antioxidant vitamins A, C and E, certain minerals like selenium and zinc, essential fats and probiotics greatly help improve the immunity. Other important nutrients that help improve response include vitamin B6, pantothenic acid, iron, folic acid, magnesium and copper.
The Thymus Gland
5.5 The thymus is a flat, pinkish-grey organ that plays an important role in the immune system of the body. It is located high in the upper chest cavity behind the breastbone and extends into the lower neck below the thyroid gland. At birth, the thymus is about 15 grams. By the age of 12, it grows to about 30 grams, but by adulthood, the organ shrinks so much that it may be hard to distinguish it from the fatty tissue that surrounds it. The thymus helps in the development of white blood cells in the bone marrow.
White Blood Cells
5.6 As integral component of the immune system, the white blood cells or leukocytes, defend the body against infection and disease. They begin their lives as immature cells in the bone marrow. As they mature, leukocytes become specialised for specific functions. The leukocytes that are important in the immune response are the macrophages, neutrophils and several types of lymphocytes. The macrophages can surround and digest harmful bacteria and other invaders. Some can move from the bloodstream to the fluid that surrounds the body cells to reach the site of infection. The lymphocytes, like trained “soldiers” are involved in the production of antibodies (defence proteins) in recognising and destroying specific types of cells, and in remembering a specific pathogen (a disease causing microorganism) in case it is encountered again.
5.7 Some of the immature lymphocytes leave the bone marrow and go to the thymus gland. There they undergo a change and become one of the different types of T-cells (for thymus) of the immune system to inhabit the blood, lymph nodes and spleen. This change takes place just before birth and during the first months of life. The thymus also functions as an endocrine gland. Its hormone, thymosin, is important to the maturation of T-cells and is thought to influence them after they leave the thyroid.
Immune System Soldiers
5.8 Like any modern army, the immune system has specially trained “soldiers” equipped to handle specific attacks. Macrophages literally surround and engulf the enemy – harmful microorganisms; T-cells, sometimes, called “natural killers”, grapple with invaders including cancer cells, in hand-to-hand combat; T-cells produce antibodies specifically designed to seek out and destroy targeted germs; neutrophils serve as the foot soldiers for this internal army. Lightly armed, the neutrophils are often among the first to enter fray enmass sacrificing in large numbers to keep the body healthy. There are also helper T-cells to assist in “combat control”, and suppressor T-cells to help calm things down once the battle has been won.
5.9 Although they possess tremendous power, the immune system soldiers are absolutely dependent on their supply system. Without the proper nutrients to keep it strong, our internal army would quickly weaken and be overrun by the enemy – the diseases. What do our immune soldiers require? The same macronutrients, comprising proteins, carbohydrates and fats, and micronutrients, comprising vitamins, minerals, phytochemicals and other substances that keep the rest of the body healthy. A deficiency of even a single vitamin or mineral can hamper the immune system, reducing the production of T-cells, impairing their ability to ingest foreign bodies, interfering with the manufacture of antibodies by the T-cells, or otherwise weakening our internal army.
The Lymph Nodes and Lymph Glands
5.10 Once the macrophages and lymphocytes mature, they circulate in the bloodstream until they reach one of the lymphatic organs, such as the lymph nodes, the spleen, or the tonsils. As lymph circulates through the lymph nodes, microphages along the walls engulf any pathogens, damaged cells, or cell debris present in the lymph fluid. Large lymph nodes are called lymph glands and are located in the armpits, in the groin and at the base of the neck. The “swollen” glands that accompany some infections are actually enlarged lymph glands.
The Spleen and Tonsils
5.11 Spleen is a large mass of lymphatic tissue between the fundus (base) of the stomach and the diaphragm. The spleen performs the same function for the blood that the lymph nodes do for the lymph. Here white blood cells rid the blood of foreign matter. The spleen contains more lymphatic tissue than any other part of the body. The tonsils are large lymph nodes found in the walls of the mouth. At birth the tonsils are quite small. They increase in size until about age 6 or 7, when they begin to shrink. The lymph nodes in the tonsils are not always able to disable invading organisms, and the tonsils frequently get infected if your immunity is low. At one time, it was standard practice to remove the tonsils if repeated infections occurred. Now they are viewed as a line of defence against invading bacteria, and are usually left in place.
Stress and the Immune System
5.12 Researchers now know that the central nervous system can communicate with the immune system and that the immune system produces chemicals that can reply to the nervous system. They have found that stressful events can actually suppress the immune system, causing the person under stress to be more susceptible to illness.
What is Fever?
5.13 The symptoms, like fever, cough, diarrhoea, headache, we perceive as diseases are actually the very processes the body’s immune system uses to restore balance, protect and heal itself. Recent research has shown that fevers represent an effort of the body organism in healing itself. Fever usually accompanies bacterial or viral infection. The body prepares itself to resist infection by developing fever; it is then more able to produce an “interferon” (an anti-viral substance). Fever also increases white blood cell mobility and activity, which are instrumental factors in fighting infection. If fevers are now becoming recognized as adaptive defences of the body, it is understandable why suppressing them with painkillers like paracetamol is now being discouraged.
What is Pus?
5.14 Pus is a mixture of white blood cells, dead pathogens, debris from broken down body cells, and plasma. It is a sign that the body’s immune system is at work. When pus collects in an infected region of the body, an abscess occurs. No abscess, no matter how small, should ever be squeezed. This can cause the bacteria to enter the bloodstream and spread to another part of the body.
6. The metabolic System
What is Metabolism?
6.1 Metabolism is the process of transforming foodstuffs into tissue elements and into energy (movement and heat) for use in growth, repair and general functions of the body, and to running a marathon. Metabolism happens in your muscles and organs and the result of it is what we commonly refer to as “burning calories”. Metabolism is essentially the speed at which your machine body’s motor is running. It is the metabolic rate that influences your energy level, mood and exactly how quickly you gain or lose weight. Most people are born with normal metabolism but their lifestyle influences it for better or worse.
6.2 Basically, our body burns calories to sustain three main functions: –
(i) Basal (Resting) Metabolic Rate (BMR) – This is the amount of energy or caloric expenditure required by the body when it is at complete rest – even when we are lying down doing nothing – to maintain body functions such as breathing, heartbeat, muscle tone, maintaining body temperature etc. BMR accounts for 60-70% of the daily calories burnt for an average person. The other 30-40% helps maintain body tissues and muscle mass. To roughly calculate, BMR multiply the body weight in kilos by 22.
(ii) Activity – This is the energy used doing movement and exertion – from lifting our arm to operate the remote control to doing housework, walking and exercising. The calories burnt, depends upon how active or passive lifestyle we have. The activity level calories roughly are 30% of BMR for inactive persons, 50% of BMR for average activity and 75% of BMR for strenuous activity.
(iii) Dietary Thermogenesis – This is food induced heat production – the digestive calories burnt in the process of eating, digesting, absorbing and assimilating food in the body. Digestive calories will be about 10% of both BMR and activity level calories. As an example, drinking 2 litres of iced water a day will burn 100 calories just heating the water to normal body temperature.
6.3 Example – For a person weighing 60 kg with average level of activity, the guideline average daily calories will be: –
1320 BMR calories (60 x 22) + 660 average activity level calories (50% of BMR calories) + 198 dietary thermogenesis calories (10% of both BMR and average activity level calories) = 2,178 calories.
How to Improve Metabolism?
6.4 Where do the Calories Go? – Liver 27%; brain 19%; muscles 18%; kidneys 10%; heart 7%; other organs 19%. Whether you are trying to lose extra kilos or compensating for the inevitable slowing down of the metabolic rate that comes with age or simply you want to remain hale and hearty, the following are some surefire ways to boost metabolism, to keep your energy pulsating and the body in shape. The more of these ways you are able to incorporate into your lifestyle, the more you will boost your metabolism. That means you will be burning more calories 24 hours a day! So bring discipline to lifestyle, get rid of negativity, have positive and cheerful attitude and bounce back with high spirits and vibrant energy with these health-giving tips: –
(i) Never wake-up to Tea or Coffee – Instead eat real natural food, which is easy on the heart, lungs, kidneys, liver and stomach, say seasonal fruit within 15 minutes of waking. Any stimulant like caffeine in tea, coffee and nicotine in cigarettes jolt the system out of slumber. It increases the blood pressure, heart and breathing rates, and makes the body feel stressed or “kicked” to which, the body will respond by slowing down metabolism and hampering fat burning. Moreover, the Cuppa can mask your hunger, so you go hungry for a longtime without realising it. All it does is create a huge calorie and nutrient deficit in the morning, and the body has no other option than to overeat later to make up the deficit. With sunrise, the metabolism peaks and the cells need nutrition. This is the time to eat and to eat big healthy breakfast. Once your cells receive nutrition through food and the blood sugar comes to an optimum level, feel free to have your tea or coffee. The breathing and heart rates etc will still increase, but now your breakfast will act as a buffer. Moderate consumption of coffee or tea (especially green) is known to boost metabolism but not first thing in the morning.
(ii) Never Skip Breakfast – Breakfast breaks the fast after 9-10 hours or more since our last meal and sleep. Your stomach and spleen (or metabolism) is at their strongest first thing in the morning. Metabolic rate is shaped like an icecream cone, highest in the morning, declining gradually through the day. Eating a seasonal fruit within 15 minutes of waking and eating substantial healthy breakfast later improves the metabolism as much as 25%. On the other hand, if you just have tea/coffee and a light bite and skip breakfast, your body thinks it is “famine” and its natural reaction, as protective mechanism, is to completely shut down the metabolism or slow it down to a crawl in an attempt to preserve whatever fuel reserves it contains as fat for the future “famine”. Since BMR accounts for 60-70% of energy expenditure, it is clearly the largest form of energy expenditure to maintain good health and ideal weight.
Those who skip breakfast are also the ones likely to develop high cholesterol, high blood pressure, blood sugar problems linked to diabetes and heart diseases. Eating breakfast has been proven to improve concentration, problem solving abilities, mental performance, memory and mood, besides good health. So make it a habit to eat breakfast like a king, lunch like a prince and dinner like a pauper.
A nutritious fulfilling breakfast should provide our 25-30% of daily nutrient needs to keep us healthy and bubbling with energy. This will also provide you the nutrient boost and will banish your cravings to binge on high calorie weight promoting junk foods in the latter part of the day, which happens if you skip breakfast. So, if you have been skipping breakfast, start eating from now on, even when you don’t feel hungry. It will take about 3 weeks to reset the biological hunger clock, once you begin.
(iii) Avoid Fasting and Feasting – Eat Small Meals Frequently – Long gaps between meals is a big destroyer of metabolism. When you fast, the body actually turns away calories, which are converted into fat. Even when the body needs energy, it actually burns muscle and holds on to the fat. There is some evidence to suggest that eating small, more frequent meals keeps the metabolism on the right path i.e. burning calories faster than large, less frequent meals. The more frequently you eat, the more frequently your metabolism will get a boost. Provided your small meals don’t fall into the quick-fix, high fat and sugar laden snacks, eating little and often can also help to control hunger and make you less likely to binge. There are two reasons why meal frequency may improve metabolism. Firstly, the levels of thyroid hormones begin to drop within hours of eating a meal, which slows metabolism. Secondly, it may be that thermogenic effect of eating several small meals is higher than eating the same amount of calories at once. So eat 7-8 small meals, say every two hours, instead of 2-3 large meals a day.
Also severely restricting your food intake for several hours to reduce weight is crazy as it actually slows metabolism and weight loss. When your body gets a regular dose of a small number of calories often, through the day, it feels reassured and loved. Eating should be a celebration and a way of loving our body and providing it with healthy nourishment. Not eating for long hours (more than 3) or starving is an act of punishment, like being angry at ourselves. When your body gets fewer calories at a time, they are metabolised better and the body sees no reason to store these as body fat.
(iv) Munch Healthy Snacks – If you can’t avoid 2-3 large meals, the next best thing is to munch a carrot or an apple or anything healthy and nutritious between meals. Other good snacking options include oatcakes with low fat soft cheese, a handful of unsalted whole nuts, vegetable sticks, low-fat or fat-free yoghurt and berries. Snacking can actually help you lose weight. Snacking prevents you from becoming too hungry. The hungrier you are, the less control you have over what and how much you eat. Also it will keep your energy/sugar levels stable and your metabolism stoked.
(v) Keep Hydrated – Your metabolism needs plenty of water to function properly. Drink 2½-3 litres of water/liquid (more in hot weather and if you exercise) at regular intervals through the day. Staying well-hydrated is essential to flushing the body of toxic waste products that are released during metabolic processes.
(vi) Eat Light Last Meal at least 2-3 hours prior to hitting the Bed – Basically our activity is lower than what it was in the morning, so is metabolism and the digestion capacity of the stomach. Therefore, eating a heavy meal late at night is a sure shot recipe for weight gain because the body stores more unburnt calories as fat during sleep. In the night, body cells are naturally not very sensitive to energy or nutrients, so if you overload your stomach, most of it will get wasted or converted to fat. Overloaded stomach will also disrupt the sleep pattern.
(vii) Eat Spicy Food – There is evidence to show that spices especially chillies, can raise the metabolic rate by upto 50% for upto 3 hours after you have eaten a spicy meal.
(viii) Increase Thermogenic Effect of Food – About 10% of the calories we consume each day are used up in metabolising and digesting what we have eaten. So consume more complex carbohydrates like wholegrains and cereals and high-fibre fruits and vegetables which burn more calories than simple carbohydrates.
(ix) Build Muscle Mass – Metabolism slows as we age by as much as 2% a year. But we can counterbalance nature by increasing and strengthening our muscle mass. Muscle tissue largely determines our metabolic rate. It is the single most important predictor of how well we metabolise our food, how well we burn calories and body fat. Our muscle tissue uses 16-22% of our daily calories just to exist. Staying fit and keeping our metabolism active involves a two-pronged strategy – burning off existing unwanted fat as well as checking its accumulation. It is most wise to invest calories in building muscle and toning up the body. So smarten up and increase the muscle mass in the body with moderate strength training exercises. Toned muscles send metabolism through the roof and it stays pumped up for many hours after the finish of the workout. For every ½ kg of muscle, the body uses upto 60 extra calories a day on average. This is because muscle is metabolically more active and burns more calories than fat and other body tissues even when we are not moving.
(x) Do Regular Exercises – Your metabolic rate is directly related to the intensity of exercise you perform. Low intensity exercise doesn’t do much for your metabolic rate but moderately high intensity does. Remember, if you are not sweating and getting tired after your brisk walk or any other exercise, then you are fooling yourself into thinking that you are doing the right thing. You have to push yourself and come out of the comfort zone to get results by exercising at 60-80% of your maximum heart rate (220 – age). Remember that even the number of calories you burn during half an hour exercise session become somewhat irrelevant; what is important is the metabolic rate at which you are burning calories both during the exercise as well as other 23½ hours of every day of your life.
(xi) Get Active and Fidget More – The level of routine activity and fidgeting help burn more calories. Be aware of this fact and adopt the hard way to do things, i.e. take every opportunity to shift, move and keep fidgeting. A few ideas for metabolising and burning calories: – stand rather than sit; tap your feet; swing your legs; drum with fingers; stand up and stretch; move your head from side to side; change position; pace up and down; use stairs more than lifts; walk or cycle than using the car for local shopping.
(xii) Get Enough Quality Sleep – A good quality, restful and peaceful sleep is the backbone to good health and losing fat. While we sleep, our body repairs and rejuvenates the cells, balances the hormones and gets ready for the work the next day. If at night the stomach is overloaded, the body’s recovery system takes a beating and the food does not get metabolised properly i.e. broken down, digested and absorbed. Adults should normally get 7-8 hours good quality sleep in a totally dark room without any trace of light contamination. Children need much more sleep and older people less. Avoid sleeping during the day except for after-lunch nap of 10-20 minutes – that too if your body needs. Sleep deprivation increases the risk of unhealthy eating, leading to weight gain. Sleep is prescribed by Nature and good sleep also improves your defence mechanism – immunity.
7. the Digestive System
What is Digestive System?
7.1 The digestive system allows your body to take in and process food to nourish its cells. It is a process from “mouth” to stomach, to intestines where the food is broken down into nutrients, which are absorbed in the blood and then supplied to all parts of the body and wastes which are excreted through bowels, urine, sweat and breath. Other digestive organs, such as the pancreas, liver and gall bladder also contribute to the process of digestion. Basically this means carbohydrates (starch), proteins and fats/oils being broken down into sugar (glucose), amino acids and so called fatty acids respectively. Ayurveda lays stress on digestion rather than nutrition. It is more important how you digest the food rather than how nutritive the food was. Of course nutrition matters but mere nutrition without proper digestion in meaningless!
The Digestive Tract (Alimentary Canal)
7.2 The digestive tract is a long tube running from the mouth down to the neck and trunk of the body, finally ending at the anus opening. If the human digestive tract were stretched out in a straight line, it would be about 95 cm. long. This long tube is also called the alimentary canal. It consists of the mouth (pharynx), foodpipe (oesophagus), the stomach, the small intestine and the large intestine. During an average lifetime about 65 tonnes of food and drink passes through the alimentary canal.
The Mouth (Pharynx) and Saliva
7.3 Saliva is produced chiefly by three pairs of salivary glands in the body. One pair is in front of the ears, one under the tongue, and one under the lower jaw. The largest glands, in front of the ears, secrete large quantities of watery saliva to moisten and to soften the food for easy chewing. The glands near the lower jaw secrete saliva to make the food slippery for easy swallowing. Which of the glands will produce the most saliva depends on the food we take in. If we bite a juicy apple, our lower glands will function to make the food slippery, as it need not be moistened. If we eat dry crackers, the glands in front of the ears will work to produce large quantities of watery saliva. The nerves in our lips, tongue, teeth and jaw muscles help us to know what we are eating. They send messages to the brain about how cold or hot our food is and whether it is rough or smooth, hard or soft.
7.4 The digestion of food begins in the mouth with the three pairs of salivary glands and continues in the stomach and the small intestines. The smell, and even the thought of food causes these glands to increase their production of saliva and our mouths start watering. Saliva contains enzymes that breakdown starches and other complex carbohydrates in food. As a person chews, food is broken into small pieces and mixed with the saliva, which moistens it and/or makes it slippery for easier swallowing. Proper chewing is essential for optimal digestion. In addition to stimulating the digestive juices in the saliva, proper chewing breaks down food, massively increasing the surface area available for contact with digestive juices. This increases the efficiency of digestion by giving stomach acid and digestive enzymes the opportunity to penetrate the food and do the digestive work. Each mouthful should ideally be chewed to a cream before swallowing.
The Stomach
7.5 After food is properly chewed and swallowed, it passes through a muscular 25 cm. long foodpipe (oesophagus or gullet) and enters the J-shaped muscular stomach. The stomach wall has three muscle layers and a mucus membrane that line it. An average adult holds about one litre of mixed food. The glands in the stomach lining secrete a variety of enzymes including pepsin, hydrochloric acid and other chemical compounds. These secretions aid in digesting the food and are collectively called gastric juices. Most of the protein and carbohydrates in the food are broken down in the stomach. The churning action of the stomach muscles furthers the digestion process by mixing the food and gastric juices. After about 3-5 hours, depending on the type, the food becomes a liquid called chyme. The chyme then passes into the small intestines.
The Intestines
7.6 The intestines are among the most amazing organs in our body, beautifully organised to do hundreds of things to the food we eat to keep alive. Intestines, about 3 metres long, stretch from the lower end of the stomach to the anus, which is the lower opening of the digestive tract. Most of the wall of the intestines consists of muscle fibres, so that the intestines can work on the food that goes through them. The intestines mix the food with certain chemicals while passing them along. Intestines are divided into two sections called the small intestine and large intestine. The small intestine consists of numerous loops, Each loop holds a bit of food and works on it, that is, churning and digesting it for about 30 minutes. Then the food is passed on to the next loop. The walls of the intestines contain nearly 20,000,000 glands that secrete many juices, which help the food to be digested and absorbed in the small intestine. The large intestine eliminates undigested wastes from the body. Billions of bacteria in the intestines breakdown the coarser parts of the food we eat, such as the skins of fruit, and extract valuable substances that the body needs. The bloodstream takes away absorbed food from the small intestine and supplies the nutrients, thus absorbed, to different tissues of the body.
The Small Intestine
7.7 The digestion of proteins and carbohydrates continues and the digestion of fats occurs in the portion of the small intestine close to the stomach on the partly digested food by the pancreatic juice, the intestinal juice and bile. The pancreatic juice pours into the small intestine through a tube or duct. The intestinal juice is produced by the walls of the small intestine. And bile is produced in the liver, stored in the gall bladder, and flows into the small intestine through a duct. Bile helps in breaking down fats.
7.8 The remainder of the small intestine performs the critical function of absorbing the digested food. The walls of the small intestine are covered with tiny projections called villi. Each villus contains tiny (capillaries) blood and lymph vessels and is covered by hair-like projections called microville. The presence of the villi and microville increases the total area to larger than a tennis court for nutrient absorption. Nutrients from the completely digested food move from the small intestine into the blood stream through the capillaries, where they are transported to the cells of the body for nourishment.
The Large Intestine (Colon)
7.9 Undigested food moves into the large intestine, where importantly water is absorbed from the waste and returned to the bloodstream. Almost no digestion or food absorption takes place in the large intestine. Peristalsis (wave like alternate contraction and relaxation) moves the solid digestive waste as well as other body wastes such as used hormones, toxins and cholesterol called faeces, through the large intestine to the rectum. Here it is stored briefly and then eliminated through the anus opening.
The Pancreas, Liver and Gall Bladder
7.10 The small intestine produces only a few digestive enzymes. Other digestive enzymes are supplied by the pancreas and the liver. These organs communicate with each other through hormonal messages that coordinate their enzyme secretions. The pancreas secretes enzymes that are active in the digestion of proteins, carbohydrates and fats. The liver secretes a greenish fluid, called bile. Bile enables large molecules of fat to be broken down. The gall bladder, a small, muscular, green sac attached to the liver, stores excess bile until it is needed. The pancreas and the liver has other functions as well. The liver is vital in regulating metabolism. Toxins, such as drugs and alcohol, are broken down by the liver. Liver also filters damaged red blood cells, debris and pathogens from the bloodstream. Pancreas produces insulin, which is vital in regulating blood-sugar levels.
The Oesophagus ( Foodpipe)
7.11 The oesophagus also called gullet is about 25 cm long muscular tube, which carries food from the mouth to the stomach. The muscles of oesophagus produce wave-like contractions to push the food down to the stomach. The surface of the oesophagus is moist and slippery due to the mucus produced by the glands in the walls of the oesophagus. Sometimes we choke while eating food. This happens when food enters the windpipe instead of the foodpipe. The openings of the windpipe as well as the foodpipe in the mouth lie close to each other, and so there are chances of food going the wrong way. This could happen when we talk while eating or if we jump around while eating. But if by chance food enters the windpipe, it can be brought back to the throat by coughing and then swallowing properly. However, in normal circumstances, when a person swallows, the epiglottis (special protective flap) closes the opening to the windpipe preventing foods or liquids from entering the lungs.
Indigestion (Dyspepsia) and its Complications
7.12 Indigestion is a common disorder producing nausea, belching, gas bloating, heartburn and abdominal cramps brought on by eating food. Indigestion is mostly due to faulty drinking and eating habits; eating too quickly, overeating, or eating junk foods like refined/starchy, fried, fat-rich and spicy foods, smoking and drinking too much alcohol and caffeine. If food is not completely digested it has the capacity to leak into the intestines (gut) wall and then further into the bloodstream. Once this happens, the body may recognise these incompletely digested foods as foreign. As a result, the body may react to these foods by mobilising the immune or some other defence system. These reactions may be designed to neutralise a foreign food, but may also provoke one or more of a wide range of the following complications and symptoms of “food intolerance”.
7.13 Complications – (i) Abdominal Bloating; (ii) Lethargy, particularly within an hour or two of eating; (iii) Mental fogginess and low mood; (iv) Mucus or catarrh in the throat, nose or sinuses; (v) Childhood problems such as colic, glue ear, ear infections and recurrent tonsillitis; (vi) Fluid retention; (vii) Eczema; (viii) Headaches and migraines (ix) Irritable Bowel Syndrome (IBS); (x) Inflammatory bowel diseases such as Crohn’s Disease; (xi) Gastro esophageal reflux disease (GERD).
7.14 Message – Good health begins on the inside. Diseases enter through the mouth. So look after your digestive system – eat healthy nutritious diet, do regular exercise and most importantly do not ignore indigestion symptoms.
Some Common Disorders of the Digestive System
7.15 The two most common disorders of the digestive system are constipation and diarrhoea. Other common problems are: –
7.16 Gastric Ulcers – During digestion, the stomach produces hydrochloric acid and enzyme pepsin (a digestive protein), which are powerful digestive juices. Normally, mucus secretions protect the body from harmful effects of these juices. But when a wrong or spicy food is eaten, or tobacco is used, or an overdose of aspirin etc is taken, then there is an overproduction of digestive juices, which break down stomach tissues resulting in an open sore, a gastric ulcer. If the sore creates damage to the blood vessels in the stomach wall, a bleeding ulcer can develop.
7.17 Stomachache – When a person complains of a stomachache, the pain is actually in the intestines. Consuming contaminated food and/or water can cause painful cramps in the intestines.
7.18 Growling and Heartburn – Our stomach starts growling at mealtimes. This sound is from the churning action of the stomach. If food is not eaten for a long time, the churning action becomes so intense that the acidic contents released from the stomach wall push upwards to damage the lining of the food pipe and produce a painful burning sensation, called heartburn, behind your breastbone and into the neck and throat. It has nothing to do with the heart! Normally, a circular valve-like muscle, called sphincter, separates the stomach and oesophagus (foodpipe), keeping the acidic content where it belongs. But if this valve becomes weak due to age or obesity, it loses its ability to stay closed. If your heartburn is bad enough, it can develop into Barrett’s oesophagus. This is a condition in which the body, in an effort to protect the oesophagus from too much stomach acid, replaces the cells, which line the oesophagus with new cells like those lining the intestines. However, this change increases your risk of cancer of the oesophagus by as much as 40 times. It starts near the heart and rises towards the throat. Sometimes, due to heartburn, the mouth gets filled with watery saliva. Heartburn may occur after drinking a hot or cold liquid. Or it may occur after eating, when a person is tense and tired, due to habitual overeating, overuse of spices, frequent use of painkillers, prolonged tension, excessive intake of tea, coffee or alcohol.
7.19 Gall Bladder Stones – The gall bladder removes water from the bile and stores it in a concentrated form. Sometimes bile becomes too concentrated, and hard concentration of minerals and salts, called gall stones, form. If the gallstones are large enough to block the flow of bile out of the gall bladder, they cause a great deal of pain.
7.20 Belching – Burps or belches are simply the sound of gas leaving your body. When we eat or drink, we also swallow air. There may be other causes like carbonated drinks and whipped products like ice cream, smoke and chewing gum. Those bubbles in the body need to escape. Gas is also produced from the stomach, travels up the foodpipe and comes out of the mouth. Usually, a belch is a body’s way of saying that the meal was good!
7.21 Flatulence – The average individual normally has 150-300 ml of gas in the stomach and intestines at any one time. On average, people pass 500-2,000 ml of gas in 10-12 episodes daily. Gas is eliminated by belching or passing it through the rectum. Men produce more gas than women do, but the flatus of women contains more of the most offensive gas, hydrogen sulphide. Gas originates from swallowed atmospheric air, bicarbonate neutralization of stomach acids, diffusion of gases into the intestine from the blood and bacterial fermentation in the intestines. The main gases produced are hydrogen and carbon dioxide and minute quantities of other gases like methane and, of course, sulphur containing compounds especially hydrogen sulphide that raises the stink. Typical culprits are non-absorbable complex carbohydrates (like soya and red kidney beans); fructose; artificial sweeteners such as sorbitol; medications; abnormal bacterial colonisation of the small intestine; abdominal distension, gaseousness and bloating; inadequate digestive enzymes; high fibre-rich diets; carbonated beverages; lactose intolerance; irritable bowel syndrome.
8. The Excretory System
What is Excretory System?
8.1 Your excretory system removes the waste products of metabolism from your body. It also removes excess water and minerals. Your kidneys are the main organ of excretion, but your respiratory and digestive systems also play a role. In addition, a small amount of waste products are excreted by the sweat glands.
The Kidneys and Urinary Tract
8.2 In addition to its role in digestion, the liver converts the toxic waste products of metabolism into less toxic ones: urea and uric acid. These and other toxic substances in the bloodstream must be removed. The renal arteries carry blood containing toxic substances to the kidneys. The kidneys remove urea and uric acid from the bloodstream and turn them into the liquid called urine. Peristaltic contractions move urine from the kidneys through the ureters to the bladder. Urine collects in the bladder until it leaves the body through the urethra.
8.3 In addition to forming urine, the kidneys maintain the body’s internal chemical balance by first removing water and minerals from the bloodstream and then reabsorbing the amount of water and minerals needed by the body. The clean blood with its adjusted chemical composition then leaves the kidneys through the renal veins. The kidneys are amazingly efficient; one healthy kidney can easily meet the body’s needs.
Urine Formation
8.4 Each kidney contains a little over 1 million blood-filtering units called nephrons. Nephrons consist of a tiny tube, or tubule, with a cup-shaped structure at one end, and they produce urine in a two-phase process. First, filtration occurs. Blood coming from the renal artery flows into the capillary network in the cup. Pressure forces water and small molecules, such as urea, out of the capillaries and into the long tubule connected to the cup. Second, reabsorption takes place. About 99 percent of the water and some of the other substances that were filtered out of the blood move into capillaries that surround the tubule. The fluid that remains in the tubule is urine. The tubules join to form larger tubes, which connect with the ureter where it joins the kidney. Urine is a concentrated mixture of water, urea, and various mineral salts. Complex mechanisms regulate urine formation, and the contents of the urine can vary depending on the state of the body. This is why an analysis of the urine, called a urinalysis, is so useful in diagnosing some diseases.
Disorders of the Urinary System
8.5 Urinary-tract infections are fairly common, especially in females. This is because the female’s urethra is much shorter than that of the male. This allows bacteria easier access to the bladder and ureters. It is important to treat urinary-tract infections early. Once an infection is well-established, it can travel up the urinary tract to the kidneys and cause a kidney infection. Acute or repeated kidney infections can cause permanent damage to the nephrons.
8.6 Kidney stones are more common in males than in females. They consist of hardened calcium salts, uric acid, and other by-products that collect inside the kidneys. Approximately 60 percent of kidney stones pass through the urethra and leave the body. If a stone becomes lodged in the ureter, it must be removed. Surgical removal was once the only option, but less invasive methods are now available. For example, fibre-optic laser surgery is used to break the stones into pieces that are small enough to pass through the urethra.
How do People Control when They Urinate?
8.7 Two circular muscles at the base of the bladder control the flow of urine from the body. Adults have voluntary control of the outermost muscle, but young children do not. The bladder can hold up to 600 ml of urine. Stretch receptors in the wall of the bladder sense how full it is, and when it contains about 200 ml, a person usually feels the need to urinate. When the volume approaches 300 ml, the need to urinate becomes urgent.
9. THE muscular System
What is Muscular System?
9.1 Your muscular system enables your body to move. Each muscle consists of muscle cells that can contract or relax. Because muscle cells are usually long and slender, they are called fibres. Skeletal muscles move your bones and help protect your inner organs. Smooth muscles deep within your body help move food, air, and body fluids. Cardiac muscle is a special type of muscle found only in your heart. Your body has more than 600 muscles, which make up about 30 percent of the female body and about 40 percent of the male body.
Skeletal Muscles
9.2 Muscles attached to bones are called skeletal muscles. They are also called “voluntary” muscles because a person can choose whether to move them. In addition to muscle fibres, skeletal muscles contain connective tissue, nerves, and blood vessels. Each muscle is surrounded by a fibrous membrane. At one end of the muscle, the fibres of this membrane connect with a tough band of elastic tissue called a tendon. Tendons connect most skeletal muscles to bones.
Smooth and Cardiac Muscles
9.3 Smooth muscles are found in internal organs, such as the stomach, intestines, urinary bladder, uterus, and blood vessels. Unlike skeletal muscles, which can be contracted voluntarily, smooth muscles are involuntary. Smooth muscles are responsible for the contractions of the oesophagus and the intestines called peristalsis. Smooth muscles are also responsible for the contractions of labour during childbirth. Cardiac muscle fibres are strong like skeletal muscles, but the heart is an involuntary muscle. The contraction and relaxation of cardiac muscle fibres pumps blood through the body automatically and rhythmically.
Muscle Action
9.4 Muscle fibres respond to nerve impulses by contracting. When enough nerve impulses are received, the entire muscle contracts and pulls any attached tissue along with it, resulting in movement of that tissue. Skeletal muscles often work in pairs to bend and straighten joints. The biceps and triceps muscles move the arms at the elbow. Contracting the biceps muscle pulls upward on one of the bones of the lower arm, causing the arm to bend. When the biceps relaxes and the triceps contracts, the arm is pulled in the opposite direction. Even the simplest body movements involve the coordination of many muscles. For example, it takes 13 muscles to smile and 34 muscles to frown.
Common Muscle Problems
9.5 Considering that muscles are used every time you move, it is not surprising that muscle injuries are common. Although regular exercise preceded by a proper warm-up reduces the risk of muscle injury, it can still occur – especially when a person ignores his or her limitations. Charley horses and pulled hamstrings are common jogging-related injuries. A charley horse is a painful contusion, or bruising, of the muscle and is frequently accompanied by a tear in muscle fibres. A pulled hamstring is an overextension or strain of one of the muscles in the back or the thigh. Inflammation of the flexor muscles of the front portion of the lower leg causes another common condition, known as shin splints. A muscular cramp is a prolonged and painful involuntary muscular contraction. A spasm is a brief, involuntary contraction. The exact cause of muscle cramps and spasms is unknown. Experts suggest that they may result from several causes: insufficient oxygen, calcium, or magnesium; fatigue; or various drugs. Tendinitis is the inflammation of the connective tissue surrounding a tendon.
Why does Muscular Fatigue develop?
9.6 The causes of muscular fatigue are not well understood. One explanation is that when muscles contract they produce lactic acid. Lactic acid creates an environment in which muscles are not able to respond to stimulation. However, new research indicates that there are other contributing factors, such as depletion of stored energy and muscle glycogen, inadequate blood flow to the muscles, and low oxygen levels. Well-conditioned athletes experience less muscle fatigue. It is known that they accumulate less lactic acid in their muscles and that conditioning actually increases the capillary density of the skeletal muscles, increasing blood flow.
Why does Weight Training make a Person look Muscular?
9.7 Muscles develop differently depending on the type of exercise they receive. For example, when a muscle is contracted moderately but repeatedly, as in swimming, it develops new capillaries and some increased strength. When a muscle is contracted in short, forceful actions, as in weightlifting, the muscle fibres increase in diameter and the entire muscle enlarges more than in repeated, moderate activity. This form of exercise increases the strength of the muscle, but a weight lifter wil not have the endurance of a swimmer.
What does it mean if a Person has Temporomandibalar Joint Syndrome (TMJ)?
9.8 Stress or a poor bite (malocclusion of the teeth) can cause some people to clench their jaw, especially in their sleep. Contracting the jaw muscles in this way causes pressure on the temporomandibular joint located in the jaw just below the ear. This can result in headaches, earaches, or pain in the jaw, neck, or shoulder. This condition is called temporomandibular joint syndrome, or TMJ. Stress management and dental splints are often prescribed for sufferers of TMJ.
10. The Skeletal System
What is Skeletal System?
10.1 Your skeletal system supports and protects the soft tissues and vital organs of your body. The skeleton is bony framework of any vertebrae (animal having a backbone). It gives the body shape and provides a system of levers operated by muscles that enable the body to move. If we did not have a skeleton, we would be floppy like a rag doll. Your heart and lungs are shielded by your ribs, your spinal cord is protected by your vertebrae, and your brain is protected by your skull. Without rigid bones and flexible joints, you would not be able to stand, sit, bend, walk, or run. By themselves, bones cannot move. Your skeletal system moves because muscles attached to your bones contract or relax in response to messages sent from the nervous system. Some of the skeletal bones are held together by strong fibres called ligaments.
The Skeleton
10.2 The human skeleton is divided into two main parts. The first part is made up of the bones of the head, neck and trunk. The spine supports the other parts of the body. The chest ribs protect the heart and lungs. The ribs move up and down, controlling the movement of air in and out of the lungs. The second part is made up of the bones of the arms and legs and their supports. The shoulder consists of the shoulder blade and the collarbone. The leg is attached to the trunk by the pelvis, which is made up of two hipbones. The pelvis supports the lower part of the abdomen, surrounds the urinary bladder and the last portion of the large intestine. The two symmetrical hip bones of the pelvis form a basin-like structure. When we sit down, much of our weight rests on these bones.
Number of Bones
10.3 The skeleton contains about 275 different size and shape bones in a baby and 206 bones in an adult depending on how they are counted. The pelvis, for instance, can be counted as a single bone or as six bones fused together. Children have 33 vertebrae in their spine, but in adults the bottom five become fused to form the sacrum. There are 24 ribs in 12 pairs, and there are 56 phalanxes (finger and toe bones). The hard shell of the skull consists of 28 bones and provides protection for the brain and the delicate sense organs. The bones of the body vary greatly in size. The thigh bone, or femur, is the largest single bone in the body. The three smallest irregular bones – the stirrup, the anvil, and the hammer – are found in the ear and are less than one-half inch long.
Composition of Bones
10.4 They may seem hard and lifeless, but bones are made of living tissue. The outer membrane of the bone, called the periosteum, contains many nerves, as well as blood vessels that transport food and oxygen to the bone’s many cells. Inside the periosteum is the bony layer, which contains more blood vessels, bone cells (osteoblasts), and nerves. At the centre of some bones is the marrow, which makes blood cells and stores fat. Bones appear to be hard and dry, like stone. Yet they are lightweight. Mineral salts like the salts of calcium and phosphorus provide the hardness. Without these salts, bones would be as soft and pliable as rubber. Bone is the most active organ in the body. Bones are continuously reshaped, remodeled and overhauled.
Bone Marrow
10.5 Bones, just like tubes, are hollow inside and are filled with spongy, red or yellow, bone marrow. Marrow is made up of tissue and fat, tiny arteries and veins, and cells that make new blood cells including red, white and platelets. The red colour of bone marrow is due to a pigment called haemoglobin that is produced there. The yellow bone marrow is mostly fat.
Bone Growth
10.6 The long bones of the body, such as the thighbone, femur, continue to grow until a person is about 20 years old. In the end of long bones is a band of cartilage called the epiphysis, or growth plate. Here, cartilage forms that will later be replaced by bone. As a young person matures, this cartilage formation slows down and finally stops. The growth plate becomes completely hardened, and growth in the length of the bone is no longer possible. Heavy exercise makes the bones grow larger, heavier and stronger. Inactivity may lead to the loss of minerals from the bones, which makes them weak and brittle.
10.7 At birth, the bones of an infant’s skull are incompletely developed and are separated by areas of soft tissue called fontanels, or soft spots. Fontanels allow for movement of the skull bones as the baby passes through the birth canal. There are no growth plates in these bones. The skull bones simply grow until they meet, closing up the soft spots. Some fontanels close up as early as two months after birth, but the one at the top of the head does not close up until about one year after birth. There are several factors that can interfere with bone growth. If the epiphysis is injured, growth in the bone may stop. Deficiencies in the diet – especially of the vitamins A, C and D – can interfere with bone growth. Steroid use by young people can cause premature closure of the epiphysis.
Cartilage
10.8 Cartilage is a tough connective tissue found in various regions of the body. In the skeletal system, cartilage connects the ribs to the sternum, helps form the movable joints and is found between the bones of the pelvis. The tip of the nose and the outer ears are made of cartilage, as are the intervertebral disks. These disks serve as cushions that prevent the vertebrae from rubbing and scraping against each other. Sometimes a disk becomes compressed and presses against a spinal nerve, which can be very painful. As people age, a disk’s outer layer may develop cracks. If the inside of the disk protrudes through a crack, a condition called a herniated disk results. Disk damage can also result from misuse of the spine, such as the repeated improper lifting of heavy objects.
Ligaments and Tendons
10.9 Ligaments, as strong as ropes, are the tough bands of tissue, which hold a joint together. They connect one bone to another. They hold the bones in place but still allow some movement. They are grouped together in cords, bands or sheets. A sprain occurs when ligaments covering a joint are torn or twisted. Sprains of the ankles and wrists are more common. A tendon (also called a sinew) is a strong white cord that connects a muscle to a bone. A tendon is a bundle of many tough fibres. Some tendons are round, others long or flat. One end of a tendon arises from the end of a muscle. The other end is woven into the substance of a bone. When the muscle contracts, the strong cable-like tendon is pulled. In turn, the tendon pulls the bone to which it is attached. The tendon may slide up and down inside a sheath of fibrous tissue just as an arm moves in a coat sleeve. The tendon and sheath are held in place by ligaments. A cut tendon may be sewed together.
The Pelvis
10.10 Although the bones of males and females are essentially alike except for size, the pelvis is an exception. To accommodate pregnancy and childbirth, the female’s pelvis has a slightly different shape than that of the male. It is usually wider so there is enough room for a developing foetus. The opening at the bottom of the pelvis is larger so that a baby’s head can pass through during childbirth. The female pelvic bones are usually lighter and have less muscle attachment. This lighter structure causes females to be more susceptible to pelvic fractures than males.
Joints
10.11 Joints are the locations where bones come together. There are three basic types of joints. Immovable joints provide little or no movement. For example, the bones that make up the skull’s cranium are joined by immovable joints called sutures. Slightly movable joints allow limited movement. This type of joint is found between the vertebrae of the spine. The names of the freely movable joints suggest the kind of motion each allows – hinge, pivot, ball-and-socket, and gliding. Hinge joints, found in the knees and elbows, allow back-and-forth movement – like a hinge in a door. Pivot joints, such as those in the neck, allow either back-and-forth movement or up-and-down movement. The shoulder and hip joints are ball-and-socket joints, which allow the greatest range of movement. Gliding joints, found in the wrist and ankles, allow for flexibility.
The Spine
10.12 The spine supports the other parts of the body. The spine runs down the back of the body from the base of the skull till the hip bone at the lower back. It consists of separate bones called vertebrae. All these bones of the spine are held together by discs of cartilage. There are 26 cotton-reel like bones in the vertebral column. Of these 7 bones are in the neck and 12 bones at the back of the chest to which the chest ribs are attached. The lower part of the back has 5 bones. The last 2 are the fused bones of the hip and the tailbone region.
Common Bone Diseases
10.13 Arthritis – There are around 200 types of arthritis which can be broadly divided into rheumatoid (inflammatory arthritis) and osteoarthritis. Osteoarthritis, a degenerative disease, is the most common. It affects primarily the weight bearing joints like the hip or knees but may affect the spine and hands as well. Osteoarthritis occurs when the cartilage that normally covers and cushions the ends of the bones breakdown due to age or excessive wear and tear. As bone rubs against bone, the joint loses shape and alignment; the ends of the bone thicken and form bony growths called spurs; and bits of cartilage or bone can float within the joint space. The result is, stiff, aching swollen joints. Rheumatoid arthritis is an autoimmune inflammatory disease attacking the cartilage in its own joints, predominantly in hands, wrists and feet. In many cases it leads to severe pain, stiffness, swelling, joint damage and loss of function of the joints. Rheumatoid arthritis has its origin in poor nutrition.
10.14 Osteoporosis – Like high blood pressure and diabetes, this progressive bone disease too strikes silently. “Osteoporosis”, which simply means “porous bones”, is second only to cardiovascular disease as a global health problem (WHO). Your bones are alive, just like other parts of the body. Bone renews itself continuously by removing old bone cells and replacing them with new cells. If too much old bone is lost and too little new bone is formed, due primarily to calcium deficiency, bone density loss can occur and the skeleton becomes porous and weak. This can set the stage for osteoporosis, a degenerative disease that over time, increases the risk of breaks and fractures, worsens your already poor posture and shaves inches off your height. There are two types of bone loss: age-related bone thinning that happens slowly in men and women; and the accelerated loss of bone mineral density that occurs in women, as estrogen levels drop after menopause – 80% osteoporosis cases happen in women. For bones to grow strong and healthy, we need to eat foods that contain calcium and vitamins A, C and D. These include dairy products, especially cheese and milk; fresh fruits and vegetables; and oily fish.
11. THE reproductive system
What is Female Reproductive System ?
11.1 A woman’s reproductive organs are more complex than those of a man because she plays a somewhat larger role than he does in the reproductive process. Reproduction in human beings involves two partners – one male and the other female. The female partner carries the young one in her body till the baby is fully formed and ready to come into the world. The process by which the baby is brought out from the body is called giving birth.
11.2 Ovaries – The primary reproductive organs – the ovaries, lie on each side of the pelvis. The two almond-shaped ovaries are about 3.5 centimetres long. They have two functions: to secrete female hormones and to produce eggs. The ovaries are covered by a layer. Internally, the ovary is distinguishable into two parts – an outer, broader zone called the cortex and an inner, narrower zone called the medulla. The cortex is filled with spherical groups of cells. These cells perform many important functions in the ovaries. They include the secretion of hormones, which play a vital role in the development of the female sexual characteristics.
11.3 Fallopian Tubes – Close to each ovary is an expanded funnel-shaped tube, down which the ova or eggs pass, when released from the ovary. This tube is called the Fallopian tube. The Fallopian tubes have finger-like projections which envelop the ovaries. They are also known as oviducts. Both oviducts are narrow tubes that open into the uterus. The oviducts have hair-like structure in their walls that sweep the ovum towards the uterus. The ovum is fertilised inside the Fallopian tube. So, the Fallopian tube is an important part of the female reproductive system. Fertilisation of the egg takes place in the Fallopian tube before it grows in another part called the uterus. If, in some cases, the Fallopian tubes are blocked, the fertilisation of the egg may not be possible at all.
11.4 The Uterus or Womb – The uterus is a large, pear-shaped, muscular, thick-walled organ, measuring about 5 centimeters by 10 centimeters and connected on either side to the Fallopian tubes. The body of the uterus is made of three coats. The innermost coat contains specially designed blood vessels and some glands. The middle coat has muscle fibres, and the outermost coat is thick and muscular. The outer layer or coat increases in weight during pregnancy. During labour it exerts a tremendous force. A healthy woman can double the total force by voluntarily contracting her abdominal muscles. Within a few weeks of birth, the uterus reverts to more or less its original size. The innermost layer forms part of the placenta during pregnancy.
What is Male Reproductive System?
11.5 A mass of coils and tubes makes up the internal genitals of a full-grown male.
11.6 Testes – The male reproductive organs, which are concerned with the formation of the male gametes or cells are the two egg-shaped glandular testes. The testes are suspended in thin pouches of skin and connective tissue, and located outside the main body cavity behind the penis. These testes exist at a temperature lower than that of the rest of the body, which is favourable for sperm production. In more than three quarters of men the right one is above the left. The testes are very sensitive and even slight pressure can cause considerable pain. If a man jumps into a cold pool of water, his testes will draw themselves up towards the crotch. Conversely, if he walks from the cold into a sauna, they lower themselves.
11.7 Epididymis – The epididymis is a storage tank consisting of 6 metre of coiled tube. It is in this storage tank that the maturation of sperms is completed. The epididymis lies alongside the testes in the scrotal sac. It stores the sperms, filters them and makes them mobile by the time they reach its posterior part. The epididymis serves as a passage for the transport of sperms. This is an important part of the male reproductive system since here the sperms are made mobile to travel around the system and finally take part in fertilisation.
11.8 Vas Deferens and Seminal Vesicles – After coming out of the testis, the epididymis becomes straight, increases in diameter and becomes a muscular tube, called the sperm duct or vas deferens. Some short tubes called seminal vesicles open into the vas deferens, enter into the abdominal cavity through a wider tube, and merge with the duct leading from the seminal vesicle gland. The seminal vesicles are tightly coiled short tubes that also store sperms. They produce fluid sugars for nourishing the sperms. The prostate gland, which surrounds part of the urethra also contributes acids, trace elements and enzymes to the sperms to form a thick milky fluid known as semen. The penis is the external male genital organ. It is a common passage for both urine and semen.
How does a New Life Begin?
11.9 The ovaries release one egg about every 28 days in a process that is called ovulation. The Fallopian tubes carry the egg to the uterus, which is located between the ovaries. The menstrual cycle is the process that prepares a woman for pregnancy. During the menstrual cycle, changes take place in the uterus. The soft inner lining of the uterus thickens, reaching its full thickness shortly after ovulation. If the egg is fertilised, it attaches itself to the lining of the uterus and starts to develop. If the egg is not fertilised by a sperm within about 21 hours, it dies. The unfertilised egg together with the inner lining of the uterus is then slowly discharged through the vagina in a process called menstruation.
Fertilisation
11.10 For fertilisation to take place in a woman’s body, it is essential that the female egg cell should fuse with the male cell. The female egg starts out very small, about the size of a little dot. The egg is fertilised in the Fallopian tube of the female. Once the egg fuses with the male cell, it undergoes various cell divisions, in which a single cell divides and becomes a number of small cells, to give rise to a zygote. When the egg and the male cell unite, some of the characteristics of the male and some of the female are preserved in the zygote.
11.11 Once the egg has been fertilised in the Fallopian tube, the cell division starts, and the developing embryo moves down the tube. After about three days, it reaches the uterus and attaches itself to the uterine wall. The placenta and other tissues vital to the life of the embryo, form at the attachment point. The placenta is a long tube which connects the mother and the embryo. And through this tube the embryo draws nourishment from the mother while it is developing in the mother’s womb. Unborn babies do not eat food the way we do. They get their food from their mother’s blood. When the mother eats food, much of the nourishment goes into her blood and then to the placenta. The placenta is where the baby’s blood and the mother’s blood meet. It is inside the womb next to the baby. The baby is joined to the placenta by a special thick tube called the umbilical cord. After the baby is born – that is, after it comes out of the mother’s body – the umbilical cord which joins the baby to the mother is cut. Later, the part of the cord left at the baby’s end, shrivels up to form the navel or the belly button. Through the cord the baby gets all the food it needs to go on growing to keep healthy. If the father or mother has some disease, it can also be transferred to the child and the baby born may be malformed. To avoid this mishap, it is important that the concerned person should get his or her disease treated.
11.12 Fertilisation, which takes place inside the female’s body, is a natural process. The mother should be healthy enough to be able to carry the baby for nine months in her womb. The baby also draws its nourishment from the mother. So in order to have a healthy baby, the mother has to eat well and be healthy herself. The baby will have features of both its mother and its father. Sometimes, the baby may be a replica of its mother or father or, for that matter, any other member of its family.
Fertilisation to Baby
11.13 During the first week after fertilisation, the fertilised egg first becomes a solid ball of cells. It later becomes hollow. During the second week it develops further and attaches itself to the lining of the uterus. Then the placenta is formed, through which the foetus draws nourishment from the mother’s blood.
11.14 The umbilical cord serves as the ‘lifeline’ between the embryo and the mother. Food, water and oxygen from the mother are absorbed by the placenta and flow through blood vessels in the umbilical cord to the embryo’s blood. The embryo’s waste material is carried through the cord to the placenta, absorbed by the mother’s body, and then expelled by the mother’s body.
11.15 During the fourth week, the embryo develops and forms various tissues and organs such as the brain, the nervous tissue, the skin, the hair, the nails and parts of the eyes and ears. The muscles, the heart, the bones, the tendons, the kidneys, the glands, the circulatory system, the reproductory organs, the lining of the digestive and respiratory system, the certain other internal organs develop at this stage.
11.16 At the end of a month the tube-shaped embryo is 6 millimetres long. The region of the head is bent and marked with ridges and grooves like the gill slits of a fish. These later become part of the face and neck. Buds on the sides of the embryo later develop into arms and legs. Other blocks of tissue along the embryo’s back develop into the various bones and muscles.
11.17 During the organisation of an embryo, the cells divide repeatedly and finally organise themselves to perform specific functions. For example, some cells become muscle cells rather than nerve cells.
11.18 During the sixth month, the baby moves and kicks. The mother can feel the movement of the baby and also the constant growth of the baby.
The Birth
11.19 For nine months the baby grows and changes shape. The mother feels a pushing inside her when the baby has to be born. This pushing takes the form of a series of contractions. It comes at regular intervals and is known as labour. This is the signal for the baby to be born. The muscles of the mother’s uterus are pushing the baby out into the world. The pushing gradually gets stronger and the mother too applies pressure so that the baby comes out easily. Normally the head of the baby comes out first and then, slowly, the rest of the body. At times the feet come out first. Once the baby breathes the air outside, it cries, as this is hard work for it. Then the doctor cuts the cord that joins the baby to its mother because now the baby does not need it any more, as it can breathe, eat, drink and expel waste by itself. The baby is thoroughly checked by the doctor. The baby’s weight is taken and a record is maintained, since this can tell the parents if the baby is growing well.
An Infant
11.20 When a baby is hungry, it cannot tell anyone about this. It may like to be cuddled, but cannot express it. It may like to walk and talk, but its bones and muscles are very soft. The only way it can express itself is by crying. For the first few months the baby can only cry, drink and sleep. As the baby develops, it acquires skills such as crawling, sitting, standing, walking and talking. The baby starts learning many things about itself and about the world around. For example, the baby recognises its mother and also responds to its name. The baby grows because it is fed regularly with mothers milk .
The Baby and the Adult
11.21 Babies are softer because their bones have not hardened. When babies are born they have few hard bones. Their skeletons are mostly made of a strong, slightly pliable material called cartilage. Later the bones grow to become bigger and harder. A child’s bones are bigger and stronger than a baby’s, but definitely not as hard as an adult’s bones. They will keep growing and getting harder until the child is about twenty-one. The bones should grow in a healthy step wise manner. Generally, if the wrist bones are growing right, then all the bones in the body will grow well. A child cannot do jobs such as lifting weights, which an adult can easily do. The mental capability of the child is limited as compared to an adult.
What makes You Grow?
11.22 Food, water and fresh air makes you grow. You need exercises like walking, running, etc to keep your muscles strong. You also need rest to grow. That is why babies sleep so much – because they are growing very fast. Your body is made up of tiny cells. You grow because these cells grow and also because new cells are added on. All foods contain different things like proteins, carbohydrates, fats, vitamins and minerals. You need the right quantity of each of these to be healthy and keep growing.
Resemblance
11.23 You may sometimes wonder whom you look like. You will probably look a little like both your father and your mother. And maybe like your grandparents or your aunt or uncle too. In the egg cell and the sperm cell there are tiny parts called genes. You get your genes from both your parents. All genes have different jobs to do – some decide your hair colour, some your eye colour, some decide your height. These genes carry all the information needed to form every part of your body. And since you have a mixture of genes from both your parents, you will look a little like both of them.
Disorders of the Reproductive System
11.24 Infertility – When a woman is not able to conceive or bear a child, or a man is not able to father children, then he/she is said to be infertile. Infertility may be temporary and treatable or it may be permanent. Infertility may result from abnormal developments, abnormal functions, or a disease of the reproductive system. In the woman, the main cause is the blockage of the Fallopian tube. Blocked tubes prevent eggs from entering the uterus, where a fertlised egg develops into a foetus. Such blockages result from infectious diseases.
11.25 Disorders of the uterus – Abnormal uterine bleeding, pelvic inflammatory disease (PID), growth of fibroids or uterine tumours are some common disorders of the uterus. The most common causes of abnormal uterine bleeding are hormonal imbalances, miscarriage, infections of the uterus, blood clotting and cancer. PID develops as a result of sexually transmitted diseases such as gonorrhea, or an infection following an abortion or childbirth. The exact cause for fibroids is not known, but fibroids often enlarge under the influence of the female hormone estrogen.
11.26 Enlargement of Prostate Gland – The prostate gland is an organ in the male reproductive system, weighing about 20 grams and about the size of a chestnut. Increasing age is the predominant cause for this disorder. The enlargement of the prostate is common among men over 50 years of age. An enlarged prostate can press the urethra. Such pressure can make the passing of urine from the body difficult and may result in bladder infection and kidney damage.
11.27 Endometriosis – It is a disease of the female reproductive system in which clusters of cells from the lining of the uterus invade other areas of the body. The areas most often affected are the ovaries and the walls of the pelvic and abdominal cavities. Endometriosis is most frequently diagnosed in women 20 to 40 years of age who have never been able to bear children. It has been believed by doctors that this disease occurs when impure blood from the uterus flows backwards into the abdominal cavity each month. This blood has clusters of uterine cells which can attach themselves to the ligaments, organs or walls of the cavity. The symptoms of endometriosis are bladder irritation and severe pain during bleeding.
Santokh Singh Parmar
Naturo-Food Therapist & Lifestyle Consultant
Mobile: +91(0) 9815922330
Websites: www.naturofoodtherapy.org & www.foodtherapy.org
April, 2009
Note: The above information and advice and indicative remedies are not a substitute for the advice, your doctor or naturo-food therapist may give you based on his/her knowledge of yourself.