The nervous system in the human body controls the working of our organs, synchronize the movement of muscles, create and obstruct the participation from the senses and instigate the movements. Nerves and neurons actively participate in this synchronization. Many nervous tissues combine to form a nervous system. The essential functions of nervous system are that it accepts and understands inputs from both external and internal environments, puts together all the inputs, and reacts to stimuli.

Nervous system

The nervous system comprises of three main parts-the brain, the nerves and the spine. The brain further consists of medulla oblongata, the cerebellum, and the cerebrum that interrelate with the nervous system. All these have different functions. Cerebellum deals in managing already learned functions of the body that includes running, walking, jumping, etc. Cerebrum duties constitute learning and thinking. Medulla takes charge of easy functions of the body like digestion and breathing. Spine mainly deals with the reflexes. It carries the inclination from and to the spinal cord.

There are four types of nerves- afferent nerves, sensory, inter neurons and motor. There are two main types of nervous systems-the Peripheral Nervous System (PNS) and central nervous system (CNS). The Peripheral Nervous System (PNS) sets a relation between central nervous system (CNS) and various parts of the body and is made by bringing together a large number of nerves. The dendrites and axons are covered by white myelin sheath. Central nervous system (CNS) consists of brain and spinal cord.

PNS is divided into two parts – autonomic nervous system and somatic nervous system.

The somatic nervous system comprise of whose function is to drive the information to the central nervous system and motor nerve fibers that venture to skeletal muscle.

In the peripheral nervous system, neurons can be categorized into three parts on the basis of their function – sensory, somatic and cranial. Sensory has the function to take the information from sense organ to the central nervous system and also to take it away from central nervous system that will further help in muscle control. Somatic links the central nervous system to the internal organs. Cranial links the spinal cord with the periphery nervous system.

The autonomic nervous system constitutes of three parts - the parasympathetic nervous system, sympathetic nervous system and enteric nervous system. This system takes control over the normal functioning of the internal organ (viscera) and other glands. Some basic points that distinguishes PNS and CNS are –

-- Clubbing together of axons in CNS are called tracts, whereas in PNS these are called nerves.
-- Clubbing together of neurons in CNS are called nuclei, and in PNS they are called ganglia.