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Nervous System
By: Zach Hardin
Nervous System
Definition
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The Nervous System consist of the
brain, spinal cord, sensory organs, and
all the nerves that connect the organs
to the rest of the body.
Functions of the Nervous
System
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Sensory: This function of the system
includes collecting information from sensory
receptors that monitor the body’s internal
and external condition.
Integration: This is the function of
processing many sensory signals that come
through the CNS at a given time.
Motor: This function happens once the CNS
evaluates the sensory information and has
decided on its action and how it will respond
to the stimulus.
Divisions of the Nervous
System
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Central Nervous System- the brain and spinal cord
come together to form the CNS. The CNS acts as
the control center for the body by providing its
processing, memory, and regulation systems. The
CNS monitor conscious and subconscious
information. The CNS is also responsible for
language, creativity, expressions, emotions, and
personality.
Peripheral Nervous System- this is all the parts of
the nervous system outside the spine and brain.
These parts of the PNS include spinal nerves,
ganglia, and sensory receptors.
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Somatic Nervous System- the SNS is a division
of the PNS that includes all of the voluntary
efferent neurons. This is the only consciously
controlled part of the PNS. The SNS is also
responsible for stimulating skeletal muscles.
Autonomic Nervous System- the ANS is also a
division of the PNS that include all involuntary
efferent neurons. The ANS controls
subconscious things such as visceral muscle
tissue, cardiac muscle tissue, and glandular
tissue.
The Nerve
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Definition: The
nerve is a bundle of
axons in the
Peripheral Nervous
System that acts
like a information
highway between
the brain, spinal
cord, and the rest
of the body.
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Axons- extend from
cell body and send
messages to other
neurons
Dendrites- extend
from the cell body
and pick up signals
from the
environment
Types of Nerves
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Afferent Nerves- this is a nerve
that carries information from
the sensory receptors to the
Central Nervous System.
Efferent Nerves- this is a nerve
that carries signals from the
Central Nervous system to
muscles and glands.
Mixed Nerves- these contain
both afferent and efferent
axons and act as a two way
street for signals.
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Cranial Nerves- these provide a
direct connection to the brain
for special sense organs. There
are 12 pair of cranial nerves.
They are identified by their
location and function.
Spinal Nerves- these are mixed
nerves that extend from left to
right. There are 31 pair of
spinal nerves. These are split
into groups: 8 pair of cervical
nerves, 12 pair of thoracic
nerves, 5 pair of lumbar
nerves, 5 pair of sacral nerves,
and 1 pair of coccygeal nerves.
The Neuron
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Neurons are cells
that communicate
with the body by
transmitting
electrical and
chemical signals. A
neuron is composed
of a cell body with
all the organelles.
Types of Neurons
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Afferent Neuron- (sensory neuron) transmits
sensory signals to the Central Nervous
System to the receptors in the body.
Efferent Neuron- (motor neuron) transmits
signals to muscles and glands in the body.
Interneurons- combine the information
received from the sensory neurons and
sends the function to the motor neurons.
Neuroglia
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This is also known as a glial
cell and the “helper” to the
nervous system.
Each neuron in the body is
covered by 6-60 neuroglia
cells.
The glial cells help the
neuron by protecting,
feeding, and insulating.
The glial cell is vital in
maintaining a functional
nervous system.
The Brain
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The brain is a soft wrinkled
organ that weighs about
three pounds.
The brain is located inside
the cranium where the
bones of the skull surround
and protect it.
The brain and the spinal
cord come together to form
the Central Nervous
System.
The Spinal Cord
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The spinal cord is a long,
thin bundle of neurons that
carry information through
the vertebral cavity.
The spine starts at the
medulla oblongata and
continues to the lumbar
region of the spine.
Cauda Equina- this is a
bundle of nerves shaped
like a horses tale located in
the lumbar region of the
spine and continuing to the
coccyx.
Cerebrospinal Fluid

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The space surrounding
the organs of the
Central Nervous
System is filled with a
clear liquid know as
Cerebrospinal Fluid.
Choroid Plexusesthese help form
cerebrospinal fluid
from blood plasma.
Functions of
Cerebrospinal Fluid.
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Absorb shock between the brain and the skull and
between the spinal cord and vertebrae.
The brain and spinal cord float in the fluid which
reduces their weight. The reduction of weight
allows the blood vessels of the brain to stay open
and help the nervous tissue from crushing under its
own weight.
The cerebrospinal fluid helps maintain chemical
homeostasis. It contains nutrients that support
chemical balance of the nervous system. The
cerebrospinal fluid also removes waste products
from cellular metabolism.
Connection to other
Systems
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The nervous system interacts with the skeletal,
cardiovascular, muscular, endocrine, lymphatic,
respiratory, digestive, reproductive, urinary, and
integumentary system.
Skeletal System- the bones of the skull protect the
brain from injury. The vertebrae protect the spinal
cord.
Cardiovascular System- cerebrospinal fluid drains
into the venous blood supply. The brain regulates
heart rate and blood pressure.
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Muscular System- receptors in the muscles
allow the brain to know the position and
movement of the body.
Endocrine System- hormones allow
information to the brain for neural
processing. Reproductive hormones affect
the development of the nervous system.
Lymphatic System- the brain can stimulate
the defense mechanisms to fight infection.
Respiratory System- the brain monitors
respiratory volume and blood gas levels.
The brain regulates respiratory rate.
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Digestive System- the autonomic nervous system
controls the tone of the digestive tract. The brain
controls drinking and eating behavior. The brain
controls the muscles for eating.
Reproductive System- reproductive hormones affect
the brains development.
Urinary System- the bladder sends sensory
information to the brain. The brain controls
urination.
Integumentary System- receptors in the skin send
sensory information to the brain. The autonomic
nervous system regulates peripheral blood flow and
sweat glands. Nerves control muscles connected to
hair follicles.
Disease: Alzheimer’s

This is a progressive, degenerative
disease that occurs in the brain and
results loss of memory, thinking, and
behavior. This disease usually occurs
in mid to old age people. This disease
is the cause of neurons breaking
connection with each other and
eventually passing.
Fun Facts about the
Nervous System
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There are more nerve cells in the human brain that
there are stars in the Milky Way.
If we were to line up all the neurons in our body, it
would be around 600 miles long.
There are 100 billion neurons in your brain alone.
There are around 13.5 million neurons in the
human spinal cord.
The total surface area of the human brain is about
25,000 square cm.
On average, you use only 4% of the cells in your
brain at any one time.
Citations
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www.infovisual.info. 8/27/13
www.naturalhealthschool.com. 8/26/13
www.thepsychologyforum.com. 8/28/13
www2.wlu.edu. 8/28/13
www.allaboutthenervoussystem.weebly.com8/27/1
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www.123rf.com. 8/26/13
www.histologygyolm.stevegall.org. 8/27/13
www.theinnerbody.com. 8/25/12
www.medicalcenter.osu.edu. 8/28/13
www.facultywashington.edu. 8/28/13