The Human nervous system controls the intentional and unintentional actions in the body. Human nervous system is a complicated linkage of nerves; they communicate data between the brain, spinal cord and remaining parts of the body. Human nervous system can be explained by dividing it into two parts.
The Central Nervous System (CNS)
The central nervous system is the chief command unit in the human body. Central nervous system mainly consists of the brain and the spinal cord. Brain is the vital component of the nervous system. The information collected is processed and response is stimulated in the brain. Brain processes the collected data by sorting it and issues necessary commands to the body. Human brain is divided into parts, each of which handles different works of the brain. Another important part of nervous system is the spinal cord; it acts as a channel through which information is traversed between the body and brain.
The Peripheral Nervous System (PNS):
The peripheral nervous system consists of a band of nerves that connect the central nervous system to rest of the body. It can be further divided into two systems namely the autonomic system and the somatic systems. The somatic system includes the body organs which take part in voluntary actions. For example, on touching a hot body we remove our hand voluntarily. In this case, the information is transmitted by sensory nerves. The autonomic system involves in the involuntary actions such as heart pumping blood throughout the body.
Coordination Between CNS and PNS:
These two systems coordinate together to control the body. These systems collect the information within the body and external to the body, they process the collected data and give instructions to the body. Human body is made of nerves and nerve cells through which communication happens between the brain and various parts of human body. The nervous system is made up of network of cells called neurons. Neurons are basic units of human nervous system and they are capable of transmitting information only in one way.
Therefore there are two classes of neurons namely sensory neurons and motor neurons. The neurons which convey information to the brain are called as sensory neurons, from the brain are called as motor neurons. Neurons receive and transmit the information in the form of electrochemical nerve impulses. Neuron is divided into the cell, dendrites, axon and myelin sheath.