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Nervous System

What does the peripheral nervous system do?

Peripheral nervous system does the following things:

  • Controls the movement of the body.
  • Controls and co-ordinates various function of the body.

what does the peripheral nervous system do?

What two systems make up the peripheral  nervous system what do they do?

The two systems that make peripheral nervous system  are as follows:

SOMATIC NERVOUS SYSTEM

The somatic nervous system includes the nerves supplying the skeletal muscle. (Voluntary controls).

The somatic nervous system controls the movement of the body by acting on the skeletal muscles.

The somatic nervous system is composed of two types of nerves. These are:

  • Cranial nerves
  • Spinal nerves

Cranial Nerves

There are 12 pairs of cranial nerves originating from nuclei in the inferior surface of the brain.

No. NAME TYPE FUNCTIONS
I Olfactory Sensory Smell.
II Optic Sensory Vision, visual information.
III Oculomotor Motor Eye movement, pupil constriction. (Moving

 

the    eye    ball    medially,    upward    and downward).

IV Trochlear Motor Eye    movement   (Moving   the   eye   ball

 

downward and outward).

V Trigeminal Mixed Sensation for the face, motor to muscles of

 

chewing.

VI Abducent Motor Eye movement (Moving eye ball laterally).
VII Facial Mixed Taste sensation, facial expression, secretion

 

of tear and saliva.

VIII Vestibulocochlear Sensory Hearing, balance
IX Glossopharyngeal Mixed Sense of taste, pharynx movement, secretion

 

of saliva.

X Vagus Mixed Heart, Lungs, GIT, ear.
XI Accessory Motor Movement of neck, shoulder.
XII Hypoglossal Motor Tongue movement.

Spinal Nerves

The nerves arising from the spinal cord are called spinal nerves. There are 31 pairs of spinal nerves.

These nerves arise from the side of spinal cord by passing through the intervertebral foramina formed by adjacent vertebra. They are:

  •  Cervical   –   8 pairs (In neck region)
  • Thoracic –   12 pairs (In thorax region)
  • Lumbar –    5 pairs (Upper abdomen region)
  • Sacral –      5 pairs (Lower abdomen region)
  • Coccygeal – 1 pair (In tail region)

The spinal nerves are mixed nerve.

They Carry both sensory (afferent) and motor (efferent) impulses.

AUTONOMIC NERVOUS SYSTEM

The system which controls and co-ordinates various function of the body “automatically” (Independently) are called autonomic nervous system.

It “automatically” controls rate of heart beat, movement of alimentary canal etc.

It is also called visceral nervous system because it innervates the visceral organs.

The activity of autonomic nervous system is controlled by medulla oblongata and hypothalamus.

The autonomic nervous system is  divided  into  two antagonistic divisions.

  • Sympathetic nervous system
  • Parasympathetic nervous system

Sympathetic nervous system

It is also known as thora columbar outflow because it arises from thoracic and lumbar region of spinal cord (T1-L2).

Parasympathetic nervous system

It is also known as craniosacral outflow because it arises from brain and sacral region of spinal cord.

How to differentiate Sympathetic and Parasympathetic effects?

  Effectors organs Sympathetic effects Parasympathetic effects  
Eye

Relaxation

Dilation

Contraction

Constriction

  Ciliary

 

muscle

 
pupil
Lacrimal

 

glands

Decrease            in

 

secretion

Increase in secretion
Salivary

 

secretion

Decrease            in

 

secretion          and vasoconstriction

Increase in secretion and vasodilation
Gall bladder Relaxation Contraction
Urinary

 

bladder

Constriction       of

 

internal sphincter

Relaxation of internal sphincter
Sweat glands Increase              in

 

secretion

Decrease in secretion
Heart Increase  Rate  and

 

force of heart

Decrease Rate and force of heart
Blood vessels Constriction of all

 

blood vessels except those in heart and skeletal muscle

Dilation
Bronchioles Dilation Constriction
     

What is central nervous system consist of?

Central nervous system is consist of brain and spinal cord.

What is brain?

Brain is the parts of central nervous system, lies in the cranial cavity. The Average weight of brain is about 1.5kg. The brain consists of the following parts:

  • Cerebrum
  • Mid brain
  • Pons
  • Medulla
  • Cerebellum

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What do you mean by meninges?

Meninges  are  connective  tissue  membrane,  covering  the  brain  and  spinal  cord.  They  lie between the skull and the brain, between vertebrae and spinal cord. The meninges have three layers.

What do you mean by blood brain barrier?

The barrier exist in the capillary membrane of all parts of brain except in some part of hypothalamus is known as blood brain barrier

What are the functions of blood brain barrier?

The main function of the blood-brain barrier (BBB) is to protect the brain from changes in the levels in the blood of ions, amino acids, peptides, and other substances.

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