The nervous system is composed of nerves and cells that carry messages between the brain and body. It has two main parts: the central nervous system containing the brain and spinal cord, and the peripheral nervous system containing nerves linking the body to the CNS. Neurons are the basic functional units and communicate chemically or electrically. The nervous system coordinates body functions through sensory input, integration in the CNS, and motor output responses.

1. General Organization
of Nervous System

2. Nervous System
 Nervous system is a complex network
of nerves and cells that carry messages
to and from the brain and spinal cord to
various parts of the body.
 The nervous system is an organ system
that coordinates activities of muscles
(voluntary and involuntary actions),
monitors organs, constructs and
processes data received from the
senses, and initiates actions. The
nervous system is a highly integrated

3. Functions of the Nervous
System
 The primary function of the nervous
system is to coordinate and control
the various body functions.
 The nervous system has three
overlapping functions based on the:
1. Sensory input.
2. Integration.
3. Motor output.

4. Functions of the Nervous
System
 Sensory Input
◦ Monitoring stimuli occurring inside &
outside the body.
◦ Gathers information from sensory
receptors.
 Integration
◦ Processes and interprets sensory input.
 Motor Output
◦ Response to stimuli by activating effector
organs to produce a response.

5. Divisions of the Nervous
System
 In most animals, including humans,
the nervous system consists of two
parts:
1) The central nervous system (CNS)
is composed of the brain and spinal
cord.
2) The peripheral nervous system
(PNS) consists of network of nerves
(sensory, motor and intermediate)
and ganglion linking the body to the

6.  Glial cells: Non-
neuronal cells that
maintain
homeostasis, form
myelin, and
provide support
and protection for
neurons in the
brain and other
parts of the
nervous system.

8. Mechanism of the Nervous
System
 In the PNS, sensory receptor neurons
respond to physical stimuli in our
environment, like touch or
temperature, and send signals that
inform the CNS of the state of the
body and the external environment.
This sensory information is then
processed by the CNS, predominantly
by the brain.

10. Neurons
 Neurons (also called nerve cells) are the
fundamental units of the brain and nervous
system. They are able to communicate with
other cells by chemical or electrical means at
synapses.
 Neuronal function is supported by
neuroglia, specialized cells which provide
nutrition, mechanical support, and protection.
 The cells responsible for receiving sensory
input from the external world, for sending
motor commands to our muscles, and for
transforming and relaying the electrical
signals at every step in between.

11. Structure of Neurons
 Cell body (soma).
 Short, branched dendrites.
 Long, single axon.
 Axon terminals

12. Functional Classification Of
Neuron
 Sensory (afferent) neurons:
Transmit impulses toward the CNS.
 Motor (efferent) neurons: Carry
impulses away from the CNS.
 Interneurons (association neurons):
Shuttle signals through CNS
pathways.

13. Structural Classifications of
Neurons
 Multipolar neurons.
 Unipolar neurons.
 Bipolar neurons.

14. Neuroglia
 Half the volume of the nervous
system.
 Special supporting tissues.
 Many types of neuroglia in CNS and
PNS.

17. Subdivisions of the Nervous
System
 The nervous system is often divided into
components:
 Gray matter: A major component of the
central nervous system, consisting of
neuronal cell bodies, dendrites and
unmyelinated axons, glial cells (astroglia
and oligodendrocytes), and capillaries.
 White matter: A region of the central
nervous system containing myelinated
nerve fibers and no dendrites mainly
composed of axons.

18. Subdivisions of the Nervous
System
 Gray Matter: Mostly cell bodies.
◦ Dendrites & terminals.
◦ Spinal reflex integrating center.
 White Matter:
◦ Bundles of myelinated axons.
 Ascending tracts – sensory.
 Descending tracts – motor.
◦ Dorsal roots.
◦ Ventral roots.