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; 

1. Sensitivity, 
2. Conductivityand 
3. Responsiveness

Neuron is the unit of nervous system:

• The structural and functional unit of nervous system is called neuron. 
• It is a special type of cell with a cell body and cell processes. 

Parts of nervous system:

Nervous system of human body is divided broadly into two parts; 

1. Central Nervous System (CNS) and
2. 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:

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; 

1. Spinal nerves and 
2. Cranial Nerves.

Spinal Nerves

• Spinal nerves arise from the spinal cord. There are 31 pairs of spinal nerves in human body. 

Cranial Nerves

• Cranial nerves arise from the brain. There are 12 pairs of cranial nerves in human body. 

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. 
•      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 increase 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 formation of an organism by different organ systems, but also for formation of a system by different organs of human body.