Nervous system helps to maintain
homeostasis, also responsible for our
perception , behavior and memories, and
intitates all voluntary movements .
3. Overview of the nervous system
With a mass o only 2 kg , about 3% of total
body weight, the nervous system is an
intricate, highly organized networks of billions
of neurons and even more neuroglia.
The structures that make up the nervous
system include the brain, cranial nerves and
theirs branches, the spinal cord, spinal nerves
and their branches, ganglia, enteric plexuses ,
and sensory receptors
4. Overview of the nervous system
The skull encloses the brain, which contains
about 100 billion neurons. Twelve pairs (right
&left) of cranial nerves, I through XII,
emerge from the base of the brain.
The spinal cord connects to the brain through
the foramen magnum of the skull and is
encircled by the bones of the vertebral
column. It contains about 100 million neurons.
5. Overview of the nervous system
Thirty –one pairs of spinal nerves emerge
from the spinal cord, each serving a specific
region on the right or left side of the body.
Ganglia are small masses of nervous tissue,
consisting primarily of neuron cell bodies, that
are located outside the brain and spinal cord.
6. Overview of the nervous system
In the walls of organs of the GIT, extensive
networks of neurons called enteric plexuses,
help regulates the digestive system.
The term sensory receptor is used to refer to
the dendrites of sensory neurons. As well as
separate, specialized cells.
7. Function of nervous system
The nervous system carries out a complex
array of tasks. It allow us to sense various
smells, produce speech, and remember past
events; in addition it provide signals that
control body movements, and regulates the
operation of internal organs.
8. Function of nervous system
These diverse activities can be grouped into
three basic functions: sensory, integrative and
Sensory function: sensory receptors detect
internal stimuli, such as an increase blood
acidity, and external stimuli carry information
into the brain and spinal cord.
9. Function of nervous system
Integrative function: the nervous system
integrative( processes) sensory information by
analyzing and storing some of it and by
making decisions for appropriate responses.
An important integrative function is
perception, the conscious awareness of
10. Function of nervous system
Motor function : Once sensory information is
integrated, the nervous system may elicit an
appropriate motor response such as muscle
contraction or gland secretion.
Motor neurons carry information from the
brain toward the spinal cord or out of the brain
and spinal cord to effectors ( muscles and
11. Organization of nervous system
The two main subdivisions of the nervous
Central nervous system (CNS) , Which
consists of the brain and spinal cord.
Peripheral nervous system (PNS), Which
includes all nerves.
12. Organization of nervous system
PNS subdivided further into a somatic nervous
system (SNS), Autonomic nervous system
(ANS) and an enteric nervous system (ENS).
13. Organization of nervous system
SENSORY PARTS OF PNS MOTOR PART OF PNS EFFECTORS
neurons in GI
tract and enteric
cells of GIT