Peripheral nervous system does the following things:
- Controls the movement of the body.
- Controls and co-ordinates various function of the body.
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
There are 12 pairs of cranial nerves originating from nuclei in the inferior surface of the brain.
|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
|VI||Abducent||Motor||Eye movement (Moving eye ball laterally).|
|VII||Facial||Mixed||Taste sensation, facial expression, secretion
of tear and saliva.
|IX||Glossopharyngeal||Mixed||Sense of taste, pharynx movement, secretion
|X||Vagus||Mixed||Heart, Lungs, GIT, ear.|
|XI||Accessory||Motor||Movement of neck, shoulder.|
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|
|Increase in secretion|
secretion and vasoconstriction
|Increase in secretion and vasodilation|
|Relaxation of internal sphincter|
|Sweat glands||Increase in
|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
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:
- Mid brain
Also Read, Definition of food adulteration.
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.
The barrier exist in the capillary membrane of all parts of brain except in some part of hypothalamus is known as 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.