Paragraph on “The Brain and Nervous System” complete paragraph for Class 9, Class 10, Class 11 and Class 12

The Brain and Nervous System

The human brain is more complex than any computer known to man. In living creatures, mammals have bigger brains and man has the biggest in relation to his size. An average human brain would weigh about 1.5 kgs and would have a jelly like texture made up of billions of living units called nerve cells or neurons. It is housed in the topmost part of the skeleton called the skull. The brain is constantly working even when we are asleep it has to control our respiratory rate, heating of the heart etc. A continuous  supply of oxygen is provided to the brain by a large number or blood vessels. The brain is divided into two primary parts called the Cerebral Hemispheres. These hemispheres have separate areas which control vision, touch, smell, taste, coordination and balance, breathing and blood pressure etc. The outer layer of the brain is called the grey matter and is rich in nerve cells, the inner layer of the brain is called the white matter and comprises largely of nerve fibres. Nerve cells are made up of spidery connections called dendrites and a long wire like fibre called the Axon. The axons are connected to other cells thus making a network of paths for nerve signals. Nerve fibres leave the brain in large bundles like cables and reach out to all parts of the body and they carry, back and forth, messages in the form of electrical impulses. The brain controls the functioning of all body parts and sensation through the nervous system, which comprises of a large number of nerves running through the body. Nerves are of two types i.e. Motor nerves which carry messages to the muscles and the sensory nerves which carry messages to and fro from the eyes, ears, nose, skin etc. When we prick our finger, signals are carried to the brain by a series of sensory nerves to the spinal cord and as a reaction messages are passed to the rooter nerves which cause the muscles to pull the finger hack, this is called a reflex action.