Digestive System
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5. The Foodpipe (Oesophagus) — The foodpipe, also called gullet, is about 25 cm long muscular tube, which carries food from the mouth to the stomach. The muscles of the foodpipe produce wave-like contractions to push the food down to the stomach. The surface of the foodpipe is moist and slippery due to the mucus produced by the glands in the walls of the foodpipe. The openings of the foodpipe as well as the windpipe in the mouth lie close to each other, and so there are chances of food going the wrong way into the windpipe and create choking. This could happen when we talk while eating or if we jump around while eating. If 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.
6. The Stomach — The chewed food passes through a muscular 25 cm long foodpipe (oesophagus or gullet) and enters the J-shaped muscular stomach. The stomach has three muscle layers and a mucous 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 (gastric juices) including hydrochloric acid, pepsin and other chemical compounds for aiding the digestion of food. Most of the proteins 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 some time the food becomes a liquid called chyme which then passes into the intestines.
7. The intestines — They are about 3 metres long and stretch from the lower end of the stomach to the anus. Most of the wall of the intestines consists of muscle fibres for working on the food that goes through them. The intestines are divided into two sections called “small intestine” and “large intestine”.
8. The Small Intestine — It 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 before passing 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. Billions of bacteria in the intestines breakdown the coarser parts of the food, such as the skins of fruit, and extract valuable nutrients that the body needs.
9. The digestion of proteins, carbohydrates and fats occurs in the portion of the small intestine closer to the stomach by pancreatic juice, the intestinal juice and the 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 the bile (a greenish fluid) is produced in the liver, excess bile stored in the gall bladder attached to the liver, and flows into the small intestine through a duct. Bile enables large molecules of fat to be broken down.
10.The remainder of the small intestine away from the stomach 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 blood and lymph vessels (capillaries) and is covered by hair-like projections called microville. The villi and microville increase 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 tissues and cells of the body for nourishment.
11. The pancreas and the liver have other functions as well. The liver is vital in regulating metabolism. Toxins, such as alcohol and drugs, are broken down by the liver. Liver also filters damaged red blood cells, debris and pathogens (disease producing agents or microorganisms) from the blood stream. Pancreas produces insulin, which is vital in regulating blood sugar levels.
12. The Large Intestine (Colon) — The undigested food moves from the small intestine into the large intestine, where importantly water is absorbed from the waste and returned to the blood stream to keep the body hydrated. 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.
13. Indigestion (Dyspepsia) and Its Complication —Indigestion can result in nausea, belching, acidity, bloating, flatulence, heartburn and abdominal cramps. Indigestion is mostly due to faulty eating and drinking habits; eating too quickly, overeating, eating junk processed 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 becomes toxic and has the capacity to leak into the intestines (gut) wall and then further into the blood stream. Once this happens, the body may recognise these incompletely digested foods as foreign. As a result, the body may react to these foreign foods by mobilising the immune or some other defence system. These reactions may neutralise a foreign food, but may also provoke one or more of a wide range of the following complications and symptoms of food intolerance.
14. Indigestion Complications — Lethargy, particularly within an hour or two of eating; mental fogginess and low mood; mucus or catarrh in the throat, nose or sinuses; headaches and migraines; fluid retention; eczema; childhood problems such as colic, glue ear, ear infections and recurrent tonsillitis; irritable bowl syndrome (IBS); inflammatory bowel diseases such as Crohn’s Disease; gastro esophageal reflux disease (GERD).
Digestive Disorders
15. The two most common disorders of the digestive system are constipation and diarrhoea:-
16. Constipation — It is a very common lifestyle disorder within the digestive tract. Having a dry hard stool, having to painfully strain too hard for a long time for it to evacuate and having incomplete evacuation or a feeling of blockage/obstruction in the annus or rectum can be termed as constipation — no matter how regular or irregular bowel movements are.
17. The most common causes of constipation are dietary pattern/wrong diet, such as low in fibre and inadequate intake of fluids, lack of exercise and sedentary lifestyle. Other causes include faulty and irregular habit of defecation and suppressing the urge to defecate, frequent use of laxatives and purgatives, old age, pregnancy, psychological/emotional problems, certain diseases like underactive thyroid and irritable bowl syndrome, iron tablets and drugs like painkillers and anti-depressants.
