Nervous system is very important in our body. Nervous system is the regulatory system that controls the activities of all physiological systems in the body and is responsible for communication in the body. For all the mental activities like learning, memory and thoughts, nervous system is the center. Together with endocrine system, homeostasis is also maintained by nervous system.
We have only one nervous system which is a complex network of nerves and nerve cells. Nerves are the cable-like structures (which are enclosed cable-like bundles of axons and nerve fibres) in the body and nerve cells are the structural and functional units of the nervous system and are also called as neurons. Nerve is formed by a group of neurons. i.e., nerve is nothing but a group of neurons. Being a complex network system, nervous system is the prime communication and coordination network of the body. It is estimated that all the individual nerves of one body if joined end to end, they could reach around the world about two and a half times. This much complex our nervous system is. As nervous system is very complex, it is difficult to understand this nervous system as a whole. Hence, to understand the nervous system easily, it has been simplified. i.e., the nervous system has been classified into a few classes for easy understanding. Primarily, it has been classified into two categories: one is central nervous system which is an integrative system with control centers and include brain and spinal cord, the other is peripheral nervous system which is the links communication between central nervous system and the rest of the body and includes cranial nerves and spinal nerves.
The central nervous system consists of brain which receives and processes sensory information, stores memories, initiates responses, generate emotions and thoughts, spinal cord which passes signals to and from brain and controls reflex activities.
The peripheral nervous system consists of motor neurons that connect central nervous system with muscles and glands, sensory neurons that connect sensory organs and central nervous system. Motor neurons again form two sub divisions called somatic nervous system which controls voluntary movements and autonomic nervous system that controls the involuntary movements/responses. The autonomic nervous system further has been divided into sympathetic division which is responsible for “fight or flight” mechanism and parasympathetic division that is responsible for “rest and digest” mechanism.
Any disturbance or deviation in the functioning of nervous system will affect the activities of the entire body. Hence, it is very important to keep nervous system healthy and any disease/disorder and/or infection has to be paid an immediate attention and cure. The further sections of this chapter will discuss about the drugs used to treat the diseases/disorders and/or infections of different parts of nervous system.