Download The Nervous System

The Nervous System
Coach Book:
Pgs. 62-65
The Main Idea:
• Your body carries out many complex
activities to keep you alive and
healthy.
• These activities must be controlled to
keep the body working properly.
• Most of the body functions are
controlled and coordinated by your
nervous system.
Importance of Nervous System
• You could not move without your nervous
system, or think, feel pain, or taste any of
your favorite foods!
• Any internal or external
change that causes a response
is called a stimulus. (plural
stimuli)
• The nervous system controls
the body’s functions and its
responses to stimuli.
• The nervous system is
composed of three main
structures: the brain, the
spinal cord, and the many
nerves throughout your body.
The Central and Peripheral
Nervous System:
• The central
nervous
system is made
up of the
brain and the
spinal cord.
The peripheral
nervous system
consists of the many
nerves that
communicate
between the central
nervous system and
the rest of the body.
Both parts of the nervous system are involved in both
voluntary and involuntary actions.
Neurons
• Your nervous system is like a giant
computer, with wires and electrical circuits
sending and receiving messages.
Neurons
• Nerve cells, or neurons,
branch out from the brain
and the spinal cord.
• Many neurons form bundles
of fibers called nerves.
• These nerves form a network
through which messages in
the form of electrical signals
can travel to all parts of the
body.
• The electrical signals carried
by neurons are called
impulses.
• Notice that the neuron is made up of three
main PARTS: dendrites, a cell body, and an
axon.
Dendrites
Cell body
Axon
• Structure of a typical nerve cell.
Neurons continued…
• Impulses travel through neurons in only
ONLY
one direction.
• An impulse is transmitted from the axon
of the one neuron to the dendrite of
another.
• The dendrite carries the impulse to the
cell body.
• The axon then carries the impulse away
from the cell body to the next neuron.
Types of Neurons
• There are 3 main TYPES:
sensory neurons, motor
neurons, and interneurons.
1. Sensory neurons - carry impulses
from the sense organs to the
spinal cord and brain.
– Sense organs are parts of your
body that take in information
from the external world.
– Most of your sense organs are
centralized in your head.
(eyes, ears, nose, & taste buds)
Types of Neurons continued…
– Your body’s largest sense organ is your skin.
– Once information is sent to the brain to
process, your brain decides how the body
will respond.
2. Motor neurons carry impulses from the brain
and spinal to the muscles and glands.
3. Interneurons, carry impulses between sensory
neurons and motor neurons.
Central Nervous System
• The central nervous
system is the control
center of the body. It
includes the brain and
spinal cord.
• The thick column of
nerve tissue that links the
brain to most of the
nerves is the spinal cord.
Central Nervous System
• The brain controls
most functions in the
body.
• The brain is located in
the head and is
protected by the skull.
Protecting the Brain
• 3 layers of connective tissue cover the
brain.
• The space between the middle layer and
inner layer is filled with a watery fluid that
helps protect it.
• The skull also protects the brain.
Parts of the brain:
1. Cerebrum - largest part of the brain.
– Interprets input from the senses, controls
movement, and carries out complex mental
processes like learning.
- Certain areas of it are associated with smell,
touch, taste, hearing, and vision.
- Other areas control movement, speech,
written language and abstract thought.
Parts of the Brain cont…
2. Cerebellum - 2nd largest part of brain.
-Coordinates the actions of your muscles
and helps you keep your balance.
3. The brain stem controls your involuntary
actions like breathing and your
heartbeat.
The Spinal Cord
• The spinal cord is a
bundle of nerves that
links the peripheral
nerves and the brain.
• The spinal cord runs
down the center of
your back and is
protected inside a
column of bones, the
vertebrae.
Central Nervous System
Central Nervous System continued…
• The brain and the spinal cord are connected
by the brain stem.
• The brain stem is the part of your nervous
system that controls your body’s involuntary
responses.
• Involuntary responses are those that are not
under your conscious control and happen
automatically. (ex. Heartbeat)
Reflexes
• Most responses are controlled
by the brain.
• However, a reflex is controlled
by the spinal cord.
• A reflex is a rapid, involuntary response to
a stimulus.
• An example, if you touch a really hot
object with your hand. The impulse is sent
to the spinal cord immediately. The spinal
cord responds by sending impulses to your
arm muscles to cause you to quickly pull
away your hand.