There are three kinds of neurons present in our body; namely sensory neurons, inter-neurons, and motor neurons. All these neurons taken together constitute the nervous system. It is a system of nerves, which is involved in perception, learning, thought processes, heartbeat, motor coordination and almost all the activities that we do. The nervous system is a complex structure that regulates bodily processes, and is responsible ultimately for all aspects of conscious experience. The nervous system of human beings is much more complex than that of any other organism.
All parts of the nervous system are interrelated. The system functions as a ‘whole’, but for purposes of theoretical discussion, the nervous system can be separated into two major divisions.
The central nervous system includes all the neurons in the brain and spinal cord. The peripheral nervous system includes all the neurons (sensory and motor neurons) connecting the brain and spinal cord to other parts of the body. The peripheral nervous system is further divided into the somatic nervous system and the autonomic nervous system. The somatic system carries messages to and from the sense receptors, muscles, and the surface of the body. It specializes in the control of voluntary movements. The autonomic system connects the internal organs and glands to the central nervous system. It is concerned with parts of the body that keeps us alive: the heart, blood vessels, glands, lungs, and other organs that function involuntarily without our awareness. The sympathetic system prepares the body to meet stressful emergency situations. In contrast, the parasympathetic system maintains the routine vital functions of the body, and clams the body after emergency situation is resolved.
Major Divisions of the Nervous System
1. Central Nervous System
- Spinal Cord
2. Peripheral Nervous System (Neural tissues outside brain and spinal cord)
- Somatic System connects central nervous system to voluntary muscles
- Autonomic system connects central nervous system to internal organs, muscles, glands.
- Sympathetic System Trouble-shooter Meets emergency situations
- Parasympathetic system House-Keeper clams body after emergency.