Brain:
It is the atomic reactor; supercomputer and also telephone exchange of our body. It is the most important part of our central nervous system. Being of great importance, it is protected by the skull and also kept floating in the cerebrospinal fluid.
Moreover, it coordinates the muscular movements while walking and running and maintains posture and equilibrium of the body. Till birth, all the activities are controlled by the small brain. After birth, its control is taken over by the big brain-the cerebrum.
The Cerebrum (Big Brain):
It is the supercomputer. All the knowledge gathered through the five senses, is passed on to the big brain through afferent nerves and this information is analysed on the basis of past knowledge and experience and necessary orders are prepared and passed on to the required organs through efferent nerves. This Cerebrum is made of two large hemispheres each containing different sets of nerves centres.
The right side of the brain controls the left side of the body while the left side of the brain controls the right side of the body. There are about 20,000 chips in this supercomputer but we hardly use 10% of the same. It is said that even for a great scientist like Albert Einstein, only 15 % of his brain was functioning.
The Cerebellum (Small Brain):
It is a bundle of nerves like an armature dynamo in a car. When blood passes through it, electricity is produced. The positive current is sent to the brain through the first ventricle and the negative current through the second ventricle. These positive and negative currents recharge the brain cells-the battery of the body and thus keep the motor neurons working. It controls and regulates the unconscious internal activities of the body.
From the thalamus all the senses are controlled, through the cerebral cortex, which consists of millions of grey matter and millions of cells of white matter inside and which in turn carry messages to and fro. Brain stem consists of midbrain, pons and medula oblongata.
Midbrain:
It is the upper part of the brain stem and is composed of the hypothalamus, thalamus, pituitary gland and limbic system. Together they control the basic drives of hunger, thirst, body temperature and activities of all the endocrine glands.
Pons:
It has a set of 12 pairs of nerves connected with the small and big brain on one side and the central nervous system through the medulla oblongata on the other side working like a relay station. It absorbs toxins from the cerebrospinal fluid which passes through it and thus controls the PH level of the body and death. It controls efferent and afferent nerves.
Medulla Oblongata:
It is also a relay-station connected with pons on one side and the brain stem-sciatic nerve-spinal cord on the other. It controls the nerves of automatic activities such as breathing and heartbeat. And so any damage to it results in immediate death.
Spinal Cord (Sciatic Nerve):
It is about 1/4 inch thick cord extending from the brain stem and going down to the coccyx where it gets divided and extends up to the end of the toes. It is also covered with three meninges and also by cerebrospinal fluid. It is made of 31 bundles of nerves which consist the both sensory and motor nerve fibres and carry out impulses to and from the brain. Upper part of the spinal cord is called Peripheral nervous system consisting of
(1) somatic system which controls the skeletal muscles and receives sensory information from the skin, muscles and
(2) automatic system which controls the involuntary working of the glands, the heart, the blood vessels and linings of stomach and intestines.
This automatic nervous system is subdivided into the sympathetic and the parasympathetic which are antagonistic in their action. While the sympathetic nerve system stimulates the activities of the connecting organs through tissues and gangalia the parasympathetic system brings these organs back to normal.
The body functions automatically as long as the vital organs get nutrition and oxygen through the blood for which the proper functioning of the lungs, heart and digestive system is absolutely necessary. Moreover, the controller of these organs i. e., the brain and central nervous system get nutrition through the cerebrospinal fluid. However, the whole body becomes listless when there is no supply of power -energy- electricity – pran – chetana life current in it. Through long and sustained research, it has been found that there are three types of electric currents-Alpha, Beta and Gama which are produced in the brain cells.