(A) Nerve cell is the structural and functional unit of nervous system.

Picture showing structure of nerve cell showing the parts of it.

(B) The part of nervous system that control the functions of the body without any need of our conscious, such as breathing, heartbeat and digestive processes, is known as autonomous nervous system.

Functions- It control and regulates the processes like breathing, sweating, digestion, heart rate.

(C) Somatic nervous system – a type of peripheral nervous system is also known as voluntary nervous system.

Example- Reflex action.

When we touch a hot pan. The afferent neuron take the information from body to the central nervous system. The brain processes the information. The efferent neurons then take the information from the brain to the body back in the form of muscle contraction, so that we can move our hand away from hot pan.