Nervous system

Definition 

The nervous system consists of brain coma spinal cord peripheral nerve. The nerves health to transmit the message grow the impulses from different part of the body to the brain and spinal cord. The nervous system in divided in following part-------

1. Central nervous system
2. Peripheral nervous system
3. Autonomic nervous system

Central nervous system

It consists then and spinal cord.

Peripheral nervous system

It consists of fall nervous outside the brain or spinal cord.

Autonomic nervous system

It consists of sympathetic and parasympathetic.

Neurone 

The nervous consist of vast number of cell called neurone. Neurone is the structural and fundamental unit of the nervous system Play Store the neurone are supported by a special type of connective tissue is called neuroglia, each neurone have a cell body and its process.

Cell body

The nerve cell are vary considered size and shape but they are too small cell body from the grey matter of The nervous system and are found at feri periphari of the brain and inter centre of the spinal cord.

Processes

this is consist of axon and dendrited these are extension of cell body and form the white matter of nervous system. Axon are found Deep in the brain and in group but out the brain and spinal cord Play Store they are known as nervous and nerve fibre.

Axon

Each nerve cell has only one axon carrying nerve impulses away from the cell body.

The axon are larger than the dendrites

(Up to 100cm).

Structure of axon

The membrane of is called axonemma and it encloses the cytoplasmic intention of the cell body the large surrounded by the mylan seath. This consists of the Schwann cell arranged along with length of axon. 

There are area of exposed axonemma between schwann sale called node of Ranveer whic assist the rapid transmission of nerve impulses .

Dendrites

 The dendrites are many short process that receive ,and carry in coming impulses towords, cell body, dendrites or shorter and branch a shape structure axon .

Nerves

The nerves are three parts ----------

1. Sensory or afferent nerve
2. Motor or efferent nerve 
3. Mixed nerve

Sensory or afferent nerve

When nerve impulses are generator by sensory retractor when the dendrites they are transmitted to spinal cord bhai sensory fibres the impulses may then pass to the brain and spinal cord they stimulated sensory nerve to different stimuli site the outside the body.

example- touch, pain, cold hot, hearing small etc. 

Motor or efferent nerves

Motor nerve originated in the brain spinal cord and transmitted impulses to the organs (Muscle and gland ,skin ).

Mixed nerve

The spinal cord sensory or motor seprete grout out site the spinal cord when sensory and within the same seath of connective tissue. They are cold mixed nerve.

Type of nerve

Central nervous system

The brain is spinal cord are completely surrounded by remembrane (meninges).

These meninges are lies between skull and brain and between vertibra and spinal cord.

These meninges are -----------------

• Duramater (outer layer)
• Arachnoid mater (middle layer)
• Pia mater (inner layer)