AIM:
How does the nervous
system work?
Do Now:
Complete the following
problem without using paper,
pen, or an electronic device:
(9 x 12 – 6) / 4+ 15 – 7=
List the processes that
occurred in your body to
complete this math problem.
How is the nervous
system used to maintain
homeostasis in the
human body?
Regulates the homeostasis
of many body systems.
The stable internal
balance of an
organism that ensures
survival
The process in which
an organism
controls and
coordinates all its
activities
THE
NERVOUS
SYSTEM
I. Nerve Cells
II. Brain
III. Central NS
IV. Peripheral NS
Consists of
Consists of:
(connected
to the spinal
cord)
(connected
to the
brain)
•The control center
•Protected by the skull
•Made up of approx.
1 trillion neurons
•Divided into two
hemispheres
Right
Left
Each hemisphere
controls the opposite
part of the body.
The brain is
Ex. The Left hemisphere
controls that right side of
divided into two
equal hemispheres the body
A look inside!!!!
The brain
consists of
three major
parts:
The largest part of
the brain
Located on both the
right and left
hemisphere
The center for
thought, memory,
learning, senses and
voluntary
movements.
Located below and
behind the
cerebrum
Coordinates all
motor activities
Maintains the
body’s balance
Located at the base
of the brain and
spinal cord
Controls
involuntary actions
Such activities
include
Heart rate
______________
Breathing rate
______________
Peristalsis
______________
•A cluster of nerves
that run along the
back
•Protected by the
Vertebrae (backbon
______________
Imagine you’ve stepped off a curb and a
car doing 70 mph, comes out of
nowhere. Identify 2 human body
systems at work to help you respond
to this stimuli. How do they interact
with one another to help you
maintain homeostasis???
Specialized structures that are
sensitive to stimuli
physical or chemical
changes within or
outside an organism
Specialized structure that
responds to commands
of the nervous system
Ex. Muscles, Glands,
Organs
How do we relay the
messages throughout our
bodies to produce an
action?
Bundles of related
nerve cells,
called neurons
that are contained in
nerve fibers
Structural unit of the brain and
nervous system which
conduct information and
carry messages throughout an
organism.
3 Types of Neurons
1. Sensory Neurons:
• Found in receptors (sense
organs)
• Receive stimulus
• Send impulses from
receptors to the spinal
cord and brain.
2. Inter-Neurons:
•Found in the spinal cord &
brain.
•Receive impulses from
sensory neurons
•Interpret “process”
stimulus
•Send impulses to the
motor neurons
3. Motor Neurons:
•Receives the
impulses from the
inter-neuron,
•Sends response
impulse to the
effectors.
Which type of nerve carries a pain
stimulus to the brain?
Sensory nerve
Sequence of events starting
from the stimulus until there
is a response.
tester
R
E
E
L
E
X
A
R
C
transmit electrochemical
messages called impulses
throughout the nerve
body.
PARTS OF A NEURON
cell body
(c y t o n)
containing the
nucleus
Dendrites:
Branched structures that
RECEIVE THE IMPULSE from
the neighboring neuron
A x o n/ (nerve fiber) :
An elongated
extension of
the cell body
that carries
impulses
away from the
cell body.
Myelin
Sheath
•Myelin Sheaths are made of fat.
•MYELIN SHEATHS insulate the
NERVE IMPULSES!!!!!
Axon terminals
The end of the axon is
divided into fingerlike
projections, which enable
Connection to the dendrites
of an adjacent neuron.
How do nerve impulses reach an
adjacent nerve cell?
There is a GAP or SPACE
between the terminal branch
(axon terminal) of a neuron
and the dendrites of another
neuron which is called a
SYNAPSE
Transmission
Across a Synapse
Impulses are carrie
d
across a synapse by
chemical messengers a r e
called
NEUROTRANSMITTERS
How do neurotransmitters affect
Nervous System Function????
Do Now: Handout HW: Handout
1. Watch the animation….using the following list of
words create a sentence that describes what your are
seeing.
Axon terminal, dendrite, synapse, neurotransmitters,
and impulse.
2. Explain the significance of the varying shapes.
After transmission
o f a n i m p u l s e …….
neurotransmitters
are destroyed
b y e n z y m e s OR they are
returned to the axon and
recycled.
Why must the body inhibit the
function of neurotransmitters?
If they were not
destroyed, they would
continue to stimulate
t h e n e r v e c e l l with the same
impulse over and over
Ex. Aspirin inhibits neurotransmitters
Name three body systems
that rely on the nervous
system for proper
functioning and explain
why you chose each.
How can the Nervous
system malfunction?
The nervous system is vulnerable to various
disorders. It can be damaged by the
following:
•trauma
•infections
•degeneration
•structural defects
•tumors
•blood flow disruption
How do certain drugs or alcoholic
beverages make you feel “high”?
Varying concentrations of the
release of neurotransmitters
Ex. Dopamine or other
chemicals
DRUGS AND EFFECTS
Stimulants like caffeine ( COLA, TEA, COFFEE,
CHOCOLATE), Nicotine (CIGARETTES) and Cocaine
increase breathing rate, heart rate and blood pressure.
They also increase the release of neurotransmitters at
some synapses in the brain.
You start to feel GREAT and then neurotransmitters
deplete and you become fatigued and even depressed. *
Abnormal levels of neurotransmitters could
cause......
1.Twitching:
Results from an over/under stimulation of
the nerve cells – Short-term malfunction
2. Tourette’s Syndrome:
Results from over stimulation of the nerve cell
leading to limited control of the particular
effectors regulated by these nerve cells.- No
cure as of today!
Abnormal levels of neurotransmitters could
cause......
3. Depression: Caused by abnormal levels
of neurotransmitters crossing the synapse
– Usually lower levels of serotonin and/or
norepinephrine
4. Schizophrenia: Caused by higher than
normal levels of dopamine
Missing Neurotransmitters could cause…..
PARKINSON’S DISEASE
ALZEIHMER’S DISEASE
DRUGS, BOTH LEGAL AND ILLEGAL,
HINDER or OVEREXCITE THE
NEUROTRANSMITTERS
Decrease of oxygen
and nutrients to the
brain, due to break of
neural/carotid blood
vessels.
Interference or
disruption between
groups of neurons
(mainly interneuron
dysfunction)
usually due to brain
trauma/injury. Symptoms
show involuntary
movement and poor
balance.
Inflammation of
tissue
surrounding the
brain and spinal
cord due to
infection.
Lou Gerhigs’ Disease: Dysfunction
of motor neurons and brain.
A viral infection affects gray
matter (of the brain) Leads to
paralysis:
Pres. Franklin D. Roosevelt
Decrease of levels of neurotransmitters
(dopamine and acetylcholine) which
affects muscle contractions. Causes
body tremors
Michael J. Fox & Mohammed Ali
Faulty gene, causes hardening of
the neurons- decreased motor
dysfunction/ coordination.
Woody Guthrie
plaque on neurons
which blocks impulse
transmission
Pres. Reagan.
Adrenoleukodystrophy
Deterioration of myelin
sheath.
Lorenzo Odone