This document provides information about the nervous system and neurons. It discusses that the nervous system controls all body functions and detects internal and external changes. It is comprised of neurons and neuroglia. Neurons consist of a cell body, dendrites, and axon. Neurons can be classified based on their structure as unipolar, bipolar, or multipolar. They can also be classified based on function as motor, sensory, or interneurons. The properties of nerve fibers include excitability, conductivity, all-or-none response, refractory period, summation, adaptation, and lack of fatigability.

1. Human Anatomy and Physiology-II
Nervous system
Neuron
Mr N.JEGAN
Associate Professor
K.M.COLLEGE OF PHARMACY.
MADURAI.

2. Content
1. Nervous tissue- Introduction
2. Nervous tissue-Contain
3. Neuron
4. Classification of Neuron
5. Properties of nerve fibre

3. Nervous system
Nervous system controls all the activities of the
body.
The nervous system detects and responds to
changes inside and outside the body.
Together with the endocrine system it
controls important aspects of body function and
maintains homeostasis.

4. Basic Functions of Nervous system
1. Sensory input - It gather information
2.Transmits information to the processing
areas of the brain and spine
3.Integration – process and interpret
sensory input
4.Motor output -response by muscles and
glands.

5. Nervous system-Contain
It include all neural tissue in the Body
Neural tissue contain two kind of cells
1.Neurone
Cell that send and receive signals
2.Neuroglia(Glial cells)
Cells that support and protect neurons.

6. Neuron

7. Structure of Neuron
Neurons or Nerve cell is the basic functional cell of nervous
system
It consist of three parts
1.Cell body
2.Axon
3.Dendrities

8. Neuron- Cell body and Dendrite
Cell body
Cell bodies-form the grey matter of the nervous
system and are found at the periphery of the brain
and in the centre of the spinal cord.
It contains the nucleus, mitochondria
and other organelles
Dendrite
Thin branching extensions of the cell
body, that conduct nerve impulses toward the cell
body

9. Axon
∙ A single branch (in most neurons) which conducts nerve impulses away
from the cell body
It also contain
Schwann Cells
cells which produce myelin or fat layer in the nervous System
∙ Myelin sheath
∙ It is an insulating layer, or sheath that forms around nerves, it
contain dense lipids. allows electrical impulses to transmit quickly and efficiently
along the nerve cells.
Node of Ranvier – gaps or nodes in the myelin sheath

11. Classification of Neuron

12. CLASSIFICATION OF NEURON
Neurons are classified by two different methods.
A. Depending upon the Structure
B. Depending upon the function

13. Depending upon the Structure
Based on the number of poles from
which the nerve fibers arise, neurons
are divided into three
1. Unipolar neurons
2. Bipolar neurons
3. Multipolar neurons.

14. Uniploar Bipolar Multiploar
From a single pole, both
axon and dendrite arise
Axon arises from one pole
and dendrites arise from the
other pole
One of the poles gives rise
to axon and all other poles
give rise to dendrites
Rare Rare 99% of neuron
skin, joints, muscles, and
internal organs.
Retina of eye Brain and Spinal cord

15. Depending upon the function
On the basis of function, nerve cells are classified into three types:
1. Motor or efferent neurons-
It carry the impulses from central nervous system to peripheral effecter
organs like muscles, glands, blood vessels, etc.
2. Sensory or afferent neurons.
It carry the sensory impulses from periphery to central nervous system
3. Interneurons
It connect sensory & motor neurons

17. Properties of nerve fibre

18. Properties of nerve fibre
1.Excitability
2.Conductivity
3.All or none law
4.Refractory period
5.Summation
6.Adaptation
7. Unfatiguability

19. 1.Excitability
Nerves can be stimulated by a suitable stimulus, Which may be
Mechanical, Thermal, Chemical and Electrical.
2.Conductivity-
Ability of nerves to transmit impulses from one place to another
place.
3. Refractory period
When a nerve fibre excited, it will not give response for second
stimulus for a brief period. This period is called refractory period

20. 4. All or none law
If a stimulus is applied always give maximum response, If a strength
or duration of simulation increased, no changes in response take place.
5. Summation
In a nerve fibre summation of two submaximal stimuli is possible
6. Adaptation
The nerves quickly adopts itself
7. Unfatiguability
Nerve fibres can not be fatigued even when they are stimulated
continuously

21. Thank you