Introduction to Nervous System:

Nervous System

Nervous System

Nervous system is the chief controlling and coordinating system of the body. It controls and regulates all voluntary and involuntary activities of human body. There are three characteristic properties of nervous system of human body; Sensitivity, Conductivity and    Responsiveness

A neuron is the unit of nervous system:

The structural and functional unit of the nervous system is called neuron. It is a special type of cell with a cell body and cell processes. For more details about the structure of neuron, see the basic anatomy article””.

Parts of nervous system:

Nervous system of human body is divided broadly into two parts; Central Nervous System (CNS) and Peripheral Nervous System (PNS)
CENTRAL NERVOUS SYSTEM (CNS) : Central nervous system includes brain and spinal cord.
PERIPHERAL NERVOUS SYSTEM (PNS) : Peripheral nervous system includes all the parts of nervous system except brain and spinal cord. It is further divided into two components; Somatic nervous system and Autonomic nervous system.


Nerves are solid cords composed of bundles of nerve fibers (each nerve fiber is an axon with its coverings) bound together by connective tissue. Nerves are of two types; Spinal nerves and Cranial Nerves.
Spinal Nerves: Spinal nerves arise from the spinal cord. There are 31 pairs of spinal nerves in human body. For more details on spinal nerves, see the basic anatomy article “”.
Cranial NervesCranial nerves arise from the brain. There are 12 pairs of cranial nerves in human body. For more details on cranial nerves, see the basic anatomy article “”.

Functions of nervous system:

  1. CONTROL OF ALL BODY FUNCTIONS: Nervous system is the master system of human body. It controls the activity of all other systems in such a way that all the systems collectively make a human being. Without a controlling system, there is no concept of life because in such case there will be no coordination between different body functions and they will all act separately. The nervous system not only controls the voluntary functions of human body that are directed by human will, but it also controls those functions that are below the level of consciousness of human beings. Control of a function means that the intensity of that function can be increased or decreased according to the demands of human body.
  2. COORDINATION OF DIFFERENT BODY ORGANS: Nervous system not only produces coordination between different systems but also between different organs of a system. To form an organ system, role of the component organs must also be coordinated. So nervous system is not only important for the formation of an organism by different organ systems, but also for the formation of a system by different organs of the human body.

Nervous System Outline:

Brain Centeral part of nervous system, Controls all body functions
Spinal Cord Long and thin bundle of nervous tissue extending from lower part of brain, transmits neural signals between brain and rest of the body
Nerves A bundle of peripheral axons enclosed by connective tissue. Carries nervous signals from nervous system to body and from body to nervous system
Nerve Endings Motor and sensory neurons end in special type of structures depending on their function. These structures are called nerve endings
Central Nervous System (CNS) Brain and Spinal Cord
Peripheral Nervous System (PNS) Cranial nerves, Spinal nerves and Ganglia

Divisions of PNS
Autonomic nervous system and Somatic Nervous System
Functions Control of all body functions, Coordination of different body organs