Human brain is a unique thing in the animal world. In fact, this is the central control system of our body. The brain coordinates all the activities of the body, such as seeing, hearing, thinking, feeling, and remembering the events. Brain is connected to the central nervous system. Nerves carry the messages to and from the brain and the body with the speed of about 400km/hr. the human nervous system has about 13 billion nerve cells, of which about 10 billion are in the brain. The left side of the brain controls the right side of the body while the right side of the brain controls the left side of the body.
The human brain is safely placed between the thick bones of the skull. An adult brain weighs about 1.4 kg.
The human brain is divided into three main parts: the cerebrum, cerebellum and medulla oblongata.
The cerebrum is the largest part of the brain. It is divided into two halves called the cerebral hemispheres. The outer surface of the cerebral hemisphere is the cortex. It contains the cell bodies of the nerves. The surface of these hemispheres is made up of grey matter. Below the grey matter is the white matter. Different regions of the cerebral hemispheres are called lobes. The frontal lobes are just behind the forehead where the processes of thinking, judgment and reasoning take place. Behind the frontal lobes are cells that control the movement of the whole body. The parietal lobes on each side of the brain receive the message connected with sensation of touch, body position, pain and temperature. The temporal lobes are the centers of hearing whereas the occipital lobes are the centers for the sense of light. One hemisphere is stronger than the other. If an individual has a dominant right eye and is right handed, then he is likely to have a dominant left hemisphere.
The cerebellum is the second largest part of the brain and lies towards the rear of the cerebrum. It is concerned with balance; position of the body and coordination of movements. This part of the brain keeps our body in equilibrium.
The third part of the brain is the brain stem which connects cerebrum and cerebellum to the spine. It contains the important hypothalamus. The cells in hypothalamus regulate the movement of the intestines, reactions to emotions and sleep. Medulla oblongata regulates breathing, heart beat and the contraction of blood vessels.
The Nervous System:
The nervous system is made up of brain, spinal cord ad nerves. Most nerves join together to form the spinal cord which runs through the backbone. The brain is connected to the rest of the body through the spinal cord. Any damage or injury to the spinal cord may stop the nerve signals from getting through.