Download The Nervous System

The Nervous
System
The Nervous System
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Functions of the nervous system
include:
coordination of the physical
movements of the body
 corresponding to the action of
the senses (hearing, tasting,
smelling, touching, and sight)
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The Nervous System
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The Nervous System is composed
of two major parts:
the Central Nervous System
 the Peripheral Nervous System
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The Nervous System
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The Central Nervous System
includes the brain and spinal cord.
This system controls most of the
voluntary responses of the animal.
The Nervous System
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The brain controls the central nervous system.
Parts of the brain include the :
cerebrum
 cerebellum
 pons
 medulla oblongata
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Regions of the Brain
The Nervous System
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The largest part of the brain is the cerebrum,
which is usually large in relation to the body size in
more intelligent animals.
The cerebrum is responsible for the decisionmaking or thinking process that controls the
voluntary muscles and reacts to the stimuli of the
senses.
The Nervous System
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The cerebellum serves as the
coordinator of the messages from
the other parts of the brain to the
body.
Reflex actions, like blinking,
breathing, and swallowing are
controlled by the pons and
medulla oblongata.
The Nervous System
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The spinal cord is the main organ
used for impulse transferal
between the brain and other parts
of the body.
The spinal cord is divided into
segments, and from each segment
a pair of spinal nerves extends to
the body.
The Nervous System
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The spinal cord receives messages from
sensory nerve fibers from various parts of the
body and transmits them to the brain.
Efferent neurons (motor nerve fibers) in the
spinal cord then transmit the responses from
the brain back to the body.
The Nervous System
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The peripheral nervous system controls the
functions of body tissues and organs.
Somatic nerves transmit signals from the outer
parts of the body to the brain.
Autonomic nerves help to control the functions
of internal organs, like the heart and stomach.
The Nervous System
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Nerve cells, called neurons,
consist of a single, long fiber,
called an axon, and several
branched threads called dendrites.
Sensory organs, like the skin,
stimulate the dendrites through
which a nerve impulse passes to
the axon.
The Nervous System
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The impulse may be conducted to an effector
organ, like a muscle cell.
The point where the dendrite is connected to the
axon is called a synapse.
Some impulses are not sent to the brain, but go
directly to the effector organ.
The Nervous System
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Nerves occur in single neurons or
in bundles, called nerve trunks.
Nerve cells that are found outside
the brain and spinal cord are
called ganglions.
The Nervous System
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Nerve cells that receive stimuli and
carry the impulses to the central
nervous system are called sensory
or afferent neurons.
Nerve cells which carry messages
from the brain to muscles or glands
are called motor or efferent
neurons.