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1.CNS.central nervous system slideshare.pptx
1. Introduction to Nervous System
RASHID KHAN MOHMAND
BS ANESTHESIA TECHNOLOGY
ANESTHESIA LECTURER
2. Definition
The nervous system is the part of a body that coordinates its
actions by transmitting signals to and from different parts of
body
The nervous system detects environmental changes that impact
the body, then works along with the endocrine system to
respond to such events
So that nervous system controls all the activities of the body.
It is quicker than othercontrol system in the body, like endocrine
system
3. Definition
Nerve impulses can be initiated in response to stimuli from:
outside the body, e.g. touch, light waves,temperature up or down
inside the body, e.g. a change in the concentration of carbon dioxide in the
blood alters respiration; a thought may result in voluntary movement
Transmission of nerve signals is both electrical and chemical. The action
potential travelling down the nerve axon is an electrical signal, but because
nerves do not come into direct contact with each other, the signal between a
nerve cell and the next cell in the chain is chemical
4. Classification
Primarily, nervous system is divided
into two parts:
1. Central nervous system- Includes
brain and spinal cord
2. Peripheral nervous system- includes
the cranial nerves and spinal nerves
5.
6. CENTRAL NERVOUS SYSTEM (CNS)
It is formed by two types of cells: neurons
and neuroglia or glial cell
The central nervous system contains more
than 100 billion neurons
Neuron are the basic conducting cells of the
nervous system
Highly specialized but cannot reproduce itself
because of absence of centrosomes in nucleus
Main parts are the cell body (soma), the fibers:
axon and dendrites
Neuroglia are supporting cells and supply
nutrients to the neurons , , 1 trillion/1000 bilion
glial cells , 10 times more then neuron
7. Layers of CNS
CNS arranged in two layers:
1. Gray matter
Nerve cell bodies and the proximal parts of nerve fibers, arising
from nerve cell body... with many cell bodies and dendrites
In brain it is outer part while in spinal cord it is inside
2. White matter
Distal parts of nerve fibers .... with many axons
In brain it is inner part while in spinal cord it is outside
9. CNS Cont’d….
Brain is situated in the skull
It is continued as spinal cord in the vertebral canal through the
foramen magnum of the skull bone
Brain and spinal cord are surrounded by three layers; called
meninges
1. The outer-dura mater
2. Middle arachnoid mater
3. Inner pia mater
10.
11. Meninges
There are three potential spaces present b/w these layers:
1. Space between arachnoid mater and pia mater is known as
subarachnoid space. This space is filled with a fluid called
cerebrospinal fluid (CSF). Brain and spinal cord are actually
suspended in the cerebrospinal fluid
2. Space between arachnoid mater and dura mater is known as
Subdural space. It have no fluid
3. Space present outside the dura mater and is known as epidural
space. It have also no fluid
13. PERIPHERAL NERVOUS SYSTEM (PNS)
It is formed by neurons and their processes present in all regions
of the body
It consists of cranial nerves, arising from brain (12 pairs) and
spinal nerves, (31 pairs) arising from the spinal cord.
It divided into two subdivisions:
1. Somatic nervous system
2. Autonomic nervous system
14. PNS Cont’d….
1. Somatic Nervous System
It is concerned with somatic functions
Like nerves supplying the skeletal muscles, responsible for muscular activities and
movements of the body
2. Autonomic Nervous System
It is concerned with regulation of viscera
So, it is also called involuntary nervous system
It consists of two divisions i.e. sympathetic division/thoracolumbar outflow T1 to
T12,L1,L2 and parasympathetic division/Craniosacral outflow - brain(III, VII,
IX and X) and S2–S4
15.
16. Function of CNS
1. Sensing the world
Vision, Hearing, Smell, Taste, Touch
2. Transmitting information
3. Processing information
4. Producing a response
