Unlike other organs, brain can receive, handle and analyse information and issue necessary commands. Human brain consists of billions of neurons and is well protected through 3 tough membranes and floats in a special liquid which absorbs shocks. The whole organ is enclosed in a bony skull. 75% of body requirement of oxygen is used by brain. 4 inter-connected arteries carry blood to brain. These arteries are connected to capillaries which reach every part of the brain. If blood supply is interrupted, we become unconscious and permanent damage to brain cells may happen. Number of neurons in the brain cell does not increase after age 5. In fact neurons die every day. Even though neurons die, the connections among them increase. Learning involves establishment of new connections.
Longest part of the brain is cerebrum. It consists of two hemispheres joined by a band of nerve fibres. The right half control the actions of the left side of the body and vice versa. Outer surface of cerebrum is cerebral cortex known as grey matter. Left part of the brain deals with information logically and helps in mathematics and problem solving while right part is responsible for creative skills. There is a balance in each activity. Hypothalamus ensures that all body processes function well at optimum. Eg: It increases breathing, if there is high level of carbon dioxide in the blood. Sweat, thirst, hunger etc.
Receives input from all sensory organs and decides which part of it should reach the concerned regions of the brain. Mid brain plays a role in wakefulness and damage to it results in coma.
Consists of cerebellum and brain stem. Cerebellum is also divided into 2 halves and lies underneath the cerebrum. It is concerned with co-ordination of muscle movements. It maintains the balance of the body. Brain stem connects it to the spinal cord. The lower part is called medulla. It helps regulate respiration, blood pressure, vomiting and other involuntary functions.
2. Spinal Cord
Spinal cord extends downwards from the brain stem through vertebrae to the bottom of the back. Its core is H-shaped in cross section and is composed of several kinds of neurons. The spinal cord is also covered by 3 membranes and contains fluid between the membranes. There are 31 pairs of spinal nerves. These nerves carry sensory signals up to the brain and motor signals from the brain to various parts of the body.