Nervous System


Nervous System
The Nervous System
The Nervous System
I. Function:
A. Communication throughout the body.
B. Coordinates functions.
C. Responds to internal and external stimuli
1. Stimuli – something that causes a change in
an organism
II. Consists of:
▫ Brain, Spinal Cord, Nerves, Sense organs
III. Basic structure of
the Nervous System
A. A nerve cell is called a neuron
B. A nerve is an organ made up of
many long neuron cells
C. Neurons carry electrical messages
called impulses throughout the
IV .Structure of a Neuron
A. Cell body: contains
nucleus & most of the
B. Dendrites: projections
that bring impulses into
the neuron to the cell
C. Axon: long projection
that carries impulses
away from cell body
D Myelin sheath –
protective “sheet”
wrapped around the
V. Bridging the Synapse
A. Neurons don’t touch one
B. The space between two
neurons is called the
C. In order for impulses to
cross the synapse they
need assistance from a
D. Neurotransmitter - special
chemical that helps to
transmit or carry impulses
between neurons
Connection to muscles or sensory organs
Drugs and pain pills
• Drugs and pain pills work
by blocking the dendrite
receptors on a nerve
• With the receptors blocked
messages, such as pain,
cannot be transferred from
one neuron to the next
VI. Types of Neurons
A. Sensory neuron – carry impulses from sense
organs to the spinal cord and brain
B. Interneuron – process impulses in the brain
and spinal cord, connect sensory and motor
neurons together
C. Motor neuron - carry impulses from the
brain & spinal cord to muscles & glands
Fun Fact:
Where can the largest
cells in the world be
The giraffe’s sensory and
motor neurons! Some must
bring impulses from the
bottom of their legs to their
spinal cord several meters
Axons branching out
to muscle fibers
• What is the name of the nerve cell ?
• Does the stimulus travel one- way or
down the neuron in two directions?
• Which part receives the stimuli? (The
synapse, dendrites, cell body, or axon)
• Which is covered by a myelin sheath ?
• What is the purpose of the myelin
VII. Reflex Arc – Involuntary Responses
A. A reflex is an involuntary response that is processed in
the spinal cord not the brain.
B. Reflexes protect the body before the brain knows what
is going on
A. Consists of the brain and spinal cord
B. Parts of the Brain
(Medulla Oblongata)
Spinal cord
1. Cerebrum
Voluntary or conscious activities of
the body-learning, judgment
2. Cerebellum
Coordinates and balances the
actions of the muscles
3. Medulla
(Brain Stem)
4. Spinal Cord
Controls involuntary actions like
blood pressure, heart rate,
breathing, and swallowing
The main communications link
between the brain and the rest of
the body
Parts of the Cerebrum
Right versus left Cerebrum
Any blow to the head does brain
damage Example of amnesia & processing skills
A. Consists of:
Sensory division and
Motor division
B. includes all sensory
neurons, motor
neurons, and sense
Of the nervous system
• Concussion
▫ Acting confused,
feeling spacey, or not
thinking straight
▫ Being drowsy, hard to
wake up, or similar
▫ Headache
▫ Loss of consciousness
• Paralysis
▫ Loss of muscle function
in part of your body
▫ Can be one area,
widespread, one side of
the body, or all of it
▫ From disease or trauma
to the spinal cord
• Infection of the membranes covering the brain
or spinal cord
• Can be bacterial or viral
Fever and chills
Mental status changes
Nausea and vomiting
Sensitivity to light (photophobia)
Severe headache
Stiff neck (meningismus)
• Caused from chemical irritation Drug allergies
Fungi Parasites Tumors
Brain eating amoeba
• When a blood clot travels to
the brain cutting off
Brain Tumors
• Neurons
Brainpop Nervous system
(Comparison of Nervous and
Endocrine Systems)
Nervous system
1. Nerves secrete
chemicals called
2. Help maintain
3. Nerve responses are
rapid and of short
4. Nerve impulses are
transmitted through
nerve cells.
Endocrine system
1. Secrete chemicals
called hormones.
2. Help maintain
3. Endocrine responses
are slow but of longer
4. Hormones are carried
by the bloodstream
• Main Function:
It releases hormones into the blood to signal
other cells to behave in certain ways. It is a
slow but widespread form of communication.
Consists of:
Endocrine glands
Release hormones into
the bloodstream.
Hormones are chemicals
released in one part of the
body that travel through
the bloodstream and
affect the activities of cells
in other parts of the body.
Pituitary Gland
Function: It secretes nine
hormones that directly regulate
many body functions and controls
functions of other glands.
Disorders: To much growth
hormones (GH) in early childhood
can result in a condition called
gigantism. To little GH can result
in Pituitary Dwarfism.
Thyroid Gland
• Function: plays a major role in regulation
the body’s metabolism.
• Disorders: If the Thyroid Gland produces
to much Thyroxin, it can cause a condition
known as Hyperthyroidism. If to little
thyroxin produces it is called
• Function: The Insulin
and Glycogen in the
Pancreas help to keep
the level of glucose in
the blood stable.
• Disorders: When the
Pancreas fails to
produce or properly use
Insulin, it can cause a
condition known as
Diabetes Mellitus.
• Diabetes -- a disorder characterized by an insulin
deficiency which results in an elevated blood sugar
(7 Diabetes Symptoms)
1. craving for sweets
2. craving for water
3. frequent urination
4. heart and circulation disorders 5. sudden changes
in vision
6. sudden changes in weight
(usually type I)
7. intense fatigue
Adrenal Gland
• Functions:
-The adrenal glands
release Adrenaline in the
body that helps prepare
for and deal with stress.
-Also regulates kidney
• Functions:
▫ Pair of reproductive organs found in
women that produce eggs.
▫ Also secrete estrogen and
progesterone, which control ovulation
and menstruation.
• Functions:
▫ Pair of reproductive glands that
produces sperm.
▫ Also secrete Testosterone to give the
body its masculine characteristics.
Interaction of Glands
The hypothalamus is
located in the brain and
controls the release of
hormones from the
pituitary gland. It is an
important link between the
endocrine and nervous
[Feedback] -- a type of organism self regulation
-- operates on the principle that the level of one
hormone in the blood inhibits or stimulates the
production of another hormone (or substance)

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