Endocrine System
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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.
