Normally mammals have bigger brains in relation to their size when compared with other living creatures and the human brain is the biggest and most developed among all the mammals. It controls all the activities of the body throughout our life. It remains active every moment directing and guiding all other organs of the body. That is why it is called the control centre of the body? But what is our brain made of and how does it carry out its different functions?
The human brain is largely made up of grey and white matter. The grey matter contains nerve cells and the white matter contains the nerve fibres. The nerve fibres carry messages from the nerve cells to different parts of the body. Thousands of electrical impulses are constantly passing through these nerve cells. All messages are first sent to the brain through different nerves from the sense organs in all parts of our body. Consequently it sends signals to different muscles and glands in the body to carry out necessary actions. The most important human activity ‘thinking’ takes place in our brain. All the energy produced in the body is used by the brain.
The central nervous system consists of the brain and the spinal cord. Different parts of the brain are interconnected and they control different activities of the body. The medulla and hypothalamus control the involuntary activities such as breathing and heart-beat. The cerebellum controls muscles and organs of balance in activities like walking or riding a bicycle that is, carrying out work automatically once we have learnt them. The cortex controls conscious feeling and voluntary movements such as writing and running. The front part is called cerebrum which has two cerebral hemispheres – the left hemisphere and the right hemisphere. This part (cerebrum) does most of the thinking and is responsible for our memory and emotions. The left hemisphere is associated with the right side of our body and the right hemisphere, with the left side. People with a more developed right hemisphere are left-handed and vice-versa.
Our brain works even when we are asleep. An adult’s brain weighs about 1.4 kg and has 14 billion nerve cells in it. The fastest messages pass along the nerves at a speed of 400 km/hr.
