Following is the description of the nervous system of a mammal which comprises of:
• The central nervous system consisting of the brain and the spinal cord.
• The peripheral nervous system consisting of the cranial nerves from the brain, the spinal nerves from the spinal cord and the sense organs.
The sense organs are the structures which receive stimuli, so they are called receptors. They keep the central nervous system informed of any change in the surroundings by initiating nervous messages called impulses which are then transmitted to the central nervous system. A nervous impulse, like an electric current, travels at great speed. It is transmitted within a fraction of a second. For instance, when a person touched your hand from behind, you feel it almost immediately.
If any action is to be taken in response to the stimulus the central nervous system will send impulses to the muscles. The muscles will then carry out the required effect e.g. the muscles in the arm may contract and the hand is jerked away. Therefore, muscles are known as effectors. The structures which transmit impulses from the receptors to the central nervous system from the latter to the effectors are the nerves.
• The central nervous system consisting of the brain and the spinal cord.
• The peripheral nervous system consisting of the cranial nerves from the brain, the spinal nerves from the spinal cord and the sense organs.
The sense organs are the structures which receive stimuli, so they are called receptors. They keep the central nervous system informed of any change in the surroundings by initiating nervous messages called impulses which are then transmitted to the central nervous system. A nervous impulse, like an electric current, travels at great speed. It is transmitted within a fraction of a second. For instance, when a person touched your hand from behind, you feel it almost immediately.
If any action is to be taken in response to the stimulus the central nervous system will send impulses to the muscles. The muscles will then carry out the required effect e.g. the muscles in the arm may contract and the hand is jerked away. Therefore, muscles are known as effectors. The structures which transmit impulses from the receptors to the central nervous system from the latter to the effectors are the nerves.
