What are the three main parts of human nervous system? What are their main functions?

The Human Nervous system is divided into the Central Nervous Systems (CNS), the Peripheral Nervous System (PNS) and the Autonomic Nervous System (ANS).

(a) Central nervous system (CNS): The Central Nervous System (CNS) consists of the brain and the spinal cord. It regulates all the activities of the body.

(b) Peripheral nervous system (PNS): The Peripheral Nervous System (PNS) includes the nerves, which form a network throughout the body. Its main function is to connect every part of the body to the Central Nervous System.

(c) Autonomic nervous system (ANS): The Autonomic Nervous System (ANS) consists of the nerves which connect the involuntary organs like the heart, stomach and lungs. Main function of autonomic nervous system is to regulate the function of internal organs.