Overview
The Nervous System
The nervous system of
the human is the most
highly organized system
of the body.
The overall function of
the nervous system is
control and coordination
of the human body.

It consists of the
brain, the spinal cord
and the nerves.

The functional,
structural unit of the
nervous system is the
nerve cell called the
neuron.

The neuron has
extensions of various
lengths from its cell
body called dentrites
and axons.
 Each cell many have
many dendrites but
only one axon.

The dendrite receives
an impulse and
passes it to the cell
body, then to the
axon where it is
passed on to muscle,
glands, or another
neuron.

There are three types
of neurons: sensory,
motor, and connecting
or associative
neurons.

Neurons do not
connect with each
other but send
impulses over spaces
called synapses.
Central Nervous System

Includes the brain and
spinal cord. The
nerves of the brain
and spinal cord do not
have the special
coating called
neurilemma, which
allows nerve cells to
repair.
Peripheral Nervous System

Composed of all the
nerves extending
from the brain (cranial
nerves) and the spinal
cord (spinal nerves).
 The peripheral
nervous system
connects the central
nervous system to
various body
structures.
Peripheral Nervous System

Cranial nerves carry
impulses to and from
the brain, and spinal
nerves carry impulses
to and from the spinal
cord.
Autonomic Nervous System

The autonomic
nervous system
controls the
involuntary or
automatic activities of
vital internal organs
such as the heart,
blood vessels and
organs of digestion.
The Brain

The brain is a
complex mass of
tissue protected by
the bony structure of
the cranium.
 The brain is further
protected by
membrane coverings
called the meninges
and cerebrospinal
fluid.
The Brain

There are three major
parts to the brain:



The cerebrum
Cerebellum
Brain stem
The Brain



The cerebrum, the largest part of the brain, is divided into two
hemispheres.
Each hemisphere is further divided into four lobes. Each lobe of the
cerebral hemispheres controls specific functions.
They are identified as the frontal, parietal, occipital, and temporal
lobes.
The Lobes of the Brain

Frontal Lobe



The cells in the right side control the voluntary motor
movements of the left side of the body.
The left side controls the right side.
The frontal lobe also controls speech.
The Lobes of the Brain

Parietal Lobe

This area receives and interprets nerve impulses from the
sensory receptors for pain, touch, heat and cold. The parietal
lobe also helps determine distance, size, and shape.
The Lobes of the Brain

Occipital Lobe

Located at the back of the brain over the
cerebellum, this lobe contains the visual area
controlling eyesight.
The Lobes of the Brain

Temporal Lobe


This lobe is located on the sides of the brain.
It contains areas which control auditory hearing and
olfactory smell.
The Brain

The outer layer of the
cerebrum is gray nerve
tissue called the cerebral
cortex.
 It is formed with deep
folds causing elevated
portions called
convolutions and furrows
or grooves called
fissures.
 These folds increase the
surface area of the
cerebral cortex.
The Brain

The cerebral cortex
controls conscious
thought, judgment,
memory, reasoning,
and willpower.
The Brain

Beneath the gray matter
of the cerebral cortex lay
the thalamus and
hypothalamus.
 The thalamus acts as a
relay center for sensory
impulses to the cerebral
cortex.
 The hypothalamus
controls temperature,
sleep, water balance, and
chemical activities.
The Cerebellum

Located at the back
and lower part of the
brain, the cerebellum
coordinates the
muscular movements
of the body, such as
balance in walking
and sitting.
The Brainstem

Made up of three
parts; midbrain, pons
and medulla.
 This part of the brain
controls and regulates
respiration and the
heart and blood
vessels.
The Spinal Cord

The spinal cord is
made up of nerve
fibers protected by
the bony structure of
the vertebra and the
spinal fluid.
 The function of the
spinal cord is to serve
as a pathway to and
from the brain.
Diseases Affecting the
Nervous System

Nerve cells often do
not repair themselves
so damage can cause
permanent loss of
function.
 Damage to the brain
and spinal cord by
force or injury may
result in death or
paralysis.
Diseases Affecting the
Nervous System

Other diseases affecting the nervous system
are Parkinsons, seizures, multiple sclerosis,
meningitis, and Cerebral vascular accident
commonly called a stroke, (which also affects
the circulatory system).
 Infections and tumors may also occur causing
illness affecting the nervous system.