Download The Nervous System

The Nervous System
Anatomy & Physiology
The Basics
• The nervous system is your body's decision
and communication center.
• The central nervous system (CNS) is made
of the brain and the spinal cord
• The peripheral nervous system (PNS) is
made of nerves.
• Together they control every part of your daily
life, from breathing and blinking to helping you
memorize facts for a test.
Brain Power: 55 sec. http://www.articlesbase.com/videos/5min/114222865
Neurons
• A neuron is a nerve cell that is the basic building block of the
nervous system.
• Neurons are specialized to transmit information throughout the
body.
• They are responsible for communicating information in both
chemical and electrical forms. There are also several different
types of neurons responsible for different tasks in the human
body.
1. Sensory neurons (afferent) carry information from the
sensory receptor cells throughout the body to the brain.
2. Motor neurons (efferent) transmit information from the
brain to the muscles of the body.
3. Interneurons are responsible for communicating
information between different neurons in the body.
We’ll get back to these later…..
Do Now!
1. What are the two main parts of the
nervous system?
2. What “organs” are these two parts made
up of?
3. What is a neuron?
4. What are the 3 different kinds of nerves?
Use the definitions
below to correctly
label this neuron
•
•
•
•
•
•
•
axon - the long extension of a neuron that carries nerve impulses away from the
body of the cell to other neurons.
axon terminals - the hair-like ends of the axon
cell body - the cell body of the neuron; it contains the nucleus (also called the soma)
dendrites - the branching structure of a neuron that receives messages (attached to
the cell body)
myelin sheath - the fatty substance that surrounds and protects some nerve fibers
node of Ranvier - one of the many gaps in the myelin sheath - this is where the
action potential occurs during saltatory conduction along the axon
nucleus - the organelle in the cell body of the neuron that contains the genetic
material of the cell
Schwann's cells - cells that produce myelin - they are located within the myelin
sheath.
Neurons
Neuron Parts:
• Soma: body of the cell
• Dendrites: receive messages
• Axon: sends messages
Anatomy of a nerve
http://www.youtube.com/watch?v=XgIa
As_ONG4&feature=related
A Neurons has three main parts. The cell body, or soma, is a neuron's
main cellular space. The soma houses the nucleus, in which the
neuron's main genetic information can be found. The axon sends
messages to other neurons. The dendrites receive messages from
other neurons.
Two parts of Nervous system &
Neuron video clip
• http://www.dnatube.com/video/2116/Anato
my-Nervous-System
• http://www.youtube.com/watch?v=DF04XP
Bj5uc&NR=1
How messages are sent and
received
• Neurons send messages electrochemically. This
means that chemicals cause an electrical signal.
• Chemicals in the body are "electrically-charged" -- when
they have an electrical charge, they are called ions.
• The important ions in the nervous system are sodium
and potassium (both have 1 positive charge, +), calcium
(has 2 positive charges, ++) and chloride (has a negative
charge, -). There are also some negatively charged
protein molecules.
• It is also important to remember that nerve cells are
surrounded by a membrane that allows some ions to
pass through and blocks the passage of other ions. This
type of membrane is called semi-permeable.
Watch Bill Nye’s Greatest Science Discoveries on Neutrotransmitters.
How messages are sent and
received continued
• Resting Membrane Potential : At rest, there is an excess of negative ions
inside the neuron compared to the outside.
•
Membrane potential. . . Charge difference between
the inside and outside of the membrane.
The charge difference is due to the difference of
concentrations of ions on either side of the cell
membrane.
Inside the membrane is negative and the outside is
positive. This is due to the permeability of ions.
There are more Na+ ions in the extracellular fluid
and more K+ ions in the intracellular fluid. The
membrane is more permeable to K+ which leaks
out to the outside of the membrane giving it a
positive charge.
http://www.youtube.com/watch?v=iAGdkje6pg&feature=related
How messages are sent and
received continued
• Action Potential
http://www.teachertube.com/viewVideo.php?video_id=
153535
• When a point on the semi-permeable neural membrane is adequately
stimulated by an incoming message, the membrane opens at that point, and
positively charged ions flow in.
• This process is repeated along the length of the membrane, creating the
neural impulse that travels down the axon, causing the neuron to fire.
•
• Electrical changes during the action potential.
The incoming message must be above a certain threshold to cause a neuron
to fire. After it fires, the neuron is returned to its resting state. This process
happens very quickly, and within a few thousandths of a second the neuron
is ready to fire again.
Action potential. . . A change in polarity across the
membrane brought about by a stimulus.
An action potential is also called a nerve impulse.
In response to a stimulus the Na+ gates open. Na+
rushes into the cell.
This causes the inside of the membrane to be positive
and the outside to be negative. This reversal of charge is
a depolarization.
K+ gates open which allow K+ out of the cell: This
causes a repolarization.
This wave of depolarization followed by a wave of
repolarization travels the length of a nerve axon and is
called an action potential. It is also called a nerve
impulse and it is how the nervous system
communicates.
Refractory period. . . The
period of rest before a
neuron can be stimulated
to fire off another action
potential.
The refractory period
insures one way
movement of action
potentials along a nerve
Pygmies short, because growth
hormone receptors are faulty and can’t
interact with growth hormone
What causes this change in
potential to occur?
• The stimulus causes the sodium gates (channel) to open
and, because there's more sodium on the outside than
the inside of the membrane, sodium then diffuses rapidly
into the nerve cell. All these positively-charged sodium
ions rushing in causes the membrane potential to
become positive (the inside of the membrane is now
positive relative to the outside). The sodium channels
open only briefly, then close again.
• The potassium channels then open, and, because there
is more potassium inside the membrane than outside,
positively-charged potassium ions diffuse out. As these
positive ions go out, the inside of the membrane once
again becomes negative with respect to the outside.
•
•
•
•
•
A message passes from a sending neuron to a receiving neuron. The neurotransmitters leave the
sending neuron and enter the space between the sending and receiving neurons. This space is
called the synapse. The neurotransmitters then hook up to a receptor on the receiving neuron to
deliver their message.
Once neurotransmitters have sent their message, they return and can be reabsorbed by the
sending neuron in a process called reuptake. Reuptake allows the messengers to be reused. Two
of these neurotransmitters are serotonin and norepinephrine. Low levels of serotonin and
norepinephrine in the synapse are associated with depression and sadness. Some medications
used to treat depression work by increasing the amount of certain neurotransmitters that are
available to carry messages.
Each type of antidepressant works on brain chemistry a little differently. All antidepressant
medications influence how certain neurotransmitters, especially serotonin and norepinephrine,
work in the brain.
SSRIs and tricyclic antidepressants. Antidepressants, such as selective serotonin reuptake
inhibitors, or SSRIs, and tricyclic antidepressants, work by slowing or blocking the sending
neuron from taking back the released serotonin. In that way, more of this chemical is available in
the synapse. The more of this neurotransmitter that is available, the more likely the message is
received, and depression is reduced. To learn more about how these antidepressants work, see
Tricyclic Antidepressants (TCAs) and Selective Serotonin Reuptake Inhibitors (SSRIs).
MAOIs. The antidepressants known as MAO inhibitors, or MAOIs, affect neurotransmitters
differently. Monoamine oxidase (MAO) is a natural enzyme that breaks down neurotransmitters.
The drug MAOI disrupts the action of the enzyme MAO. In that way, there is an increase in the
amount of neurotransmitters in the synapse, making more messengers available to the receiving
neuron, and thus reducing depression. To learn more about how these antidepressants work, see
Monoamine Oxidase Inhibitors (MAOIs).
Nerve Function and Drug Action:
http://www.utexas.edu/research/asrec/neuroncartoon.html
Neuron parts
http://garyfisk.com/anim/neuronparts.swf
Animated visual:
http://www.classzone.com/cz/books/bio_0
7/get_chapter_group.htm?cin=9&rg=anim
ated_biology&at=animated_biology&var=a
nimated_biology
Myelin and Nodes of Ranvier
• Axons are sheathed in a smooth fatty protein called myelin
which insulates the axon, prevents the wrong ion channels
from opening and considerably increases the speed that nerve
impulses travel along the axon.
• Without the myelin, the axons would have to be about one
hundred times their volume to achieve the same speed of nerve
transmissions. The myelin is wrapped around the axon in many
thin layers. The myelin does not enclose the axon in one entire
sheath, but has gaps at intervals called the nodes of Ranvier.
• The precise function of these nodes is unknown but the nodes
are major sites of sodium channels and may serve to prevent
the decay of nerve impulses by effectively amplifying them.
• They may also act to anchor the myelin sheath to the axon and
to isolate each segment of myelin from its neighbors.
• Work on rats with genetic deformities in their nodes of Ranvier
has shown that these nodes are vital to efficient transmission
of nerve impulses. How the myelin sheath works is discussed
more fully in the section on myelin.
Quiz Time!
Name the …..
1. Part of the neuron that releases neurotransmitters
into the synaptic cleft.
2. Fatty material that surrounds some axons.
3. Part that takes information away from the cell body.
4. The gaps in the myelin sheath.
5. Part of neuron that contains the nucleus.
6. Part that takes information to the cell body.
7. Organelle in neuron that contains genetic material.
Answers are:
1. Axon terminal
4. Nodes of Ranvier
2. Myelin
5. Soma
3. Axon
6. Dendrites
7. Nucleus
The Central Nervous System
Interesting Facts!
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
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The central nervous system is divided into two parts:
the brain and the spinal cord.
The average adult human brain weighs 1.3 to 1.4 kg
(approximately 3 pounds).
The brain contains about 100 billion nerve cells
(neurons) and trillons of "support cells" called gila.
The spinal cord is about 43 cm long in adult women and
45 cm long in adult men and weighs about 35-40 grams.
The vertebral column, the collection of bones (back
bone) that houses the spinal cord, is about 70 cm long.
Therefore, the spinal cord is much shorter than the
vertebral column.
young frankenstein part 1
The CNS: The Brain
• The cerebrum -- which is just Latin for "brain" -- is the
newest (evolutionarily) and largest part of the brain as
a whole. It is here that things like perception,
imagination, thought, judgment, and decision occur.
• The surface of the cerebrum -- the cerebral cortex -- is
composed of six thin layers of neurons (nerve cells) and is
referred to as the grey matter. It sits on top of a large
collection of white matter pathways.
• The cortex is heavily convoluted with “ridges” called gyri
and “valleys” called sulci. If you were to spread the
cortex out, it would actually take up about 2 1/2 square
feet (2500 sq cm). It includes about 10 billion neurons,
with about 50 trillion synapses!
• The cerebral cortex is divided into four sections, called
"lobes": the frontal lobe, parietal lobe, occipital lobe, and
temporal lobe.
•
• Grey matter – closely packed neuron cell bodies (making
up the cerebral cortex) form the grey matter of the brain.
The grey matter includes regions of the brain involved in
muscle control, sensory perceptions, such as seeing and
hearing, memory, emotions and speech.
• White matter – neuronal tissue containing mainly long,
myelinated axons, is known as white matter or the
diencephalon. It makes up the cerebrum.
• The nuclei of the white matter are involved in the relay of
sensory information from the rest of the body to the
cerebral cortex, as well as in the regulation of autonomic
(unconscious) functions such as body temperature, heart
rate and blood pressure.
• Certain nuclei within the white matter are involved in the
expression of emotions, the release of hormones from the
pituitary gland, and in the regulation of food and water
intake. These nuclei are generally considered part of the
limbic system.
4 Main Parts of the Brain
The Brain
The cerebral
cortex is
comprised of
the:
frontal lobe,
parietal lobe,
occipital lobe,
and temporal
lobe.
What do each of these lobes do?
• Frontal Lobe- associated with reasoning,
planning, parts of speech, movement,
emotions, and problem solving
Functions associated with the frontal lobes:
Conscious thought
Concentration
Perseverance
Judgment
Attention span
Impulse control - self monitoring and
supervision
Problem solving
Organization
Critical thinking
Forward thinking
Ability to feel and express emotions
Empathy
YouTube - NEURONS AND
NEURO-TRANSMITTERS
What do each of these lobes do?
• Frontal Lobe- associated with reasoning,
planning, parts of speech, movement,
emotions, and problem solving
• Parietal Lobe- associated with movement,
orientation, recognition, perception of stimuli
Parietal Lobe
• The parietal lobes can
be divided into two
functional regions.
• One involves
sensation and
perception and the
other is concerned with
integrating sensory
input, primarily with the
visual system.
What do each of these lobes do?
• Frontal Lobe- associated with reasoning,
planning, parts of speech, movement,
emotions, and problem solving
• Parietal Lobe- associated with movement,
orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual
processing
Occipital lobes
• The OC are the center of our
visual perception system.
They are not particularly
vulnerable to injury because
of their location at the back of
the brain, although any
significant trauma to the brain
could produce subtle
changes to our visualperceptual system, such as
visual field defects.
What do each of these lobes do?
• Frontal Lobe- associated with reasoning, planning,
parts of speech, movement, emotions, and problem
solving
• Parietal Lobe- associated with movement,
orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual processing
• Temporal Lobe- associated with perception and
recognition of auditory stimuli, memory, and speech
TEMPORAL LOBES: Located at sides of head
above ears, the temporal lobes form the wings of
the soul of our living caduceus.
Functions:
The dominant side is usually the left hand side
and governsHearing ability
Understanding and processing language
Memory acquisition - particularly long term
memory
Some visual perceptions
Categorization of objects.
The no dominant side or right side governsRecognition of facial expressions
Decoding vocal intonation
Rhythm
Music
Visual learning
How your memory works?
The right hemisphere
controls the left side of the
body, and the left
hemisphere controls the
right side.
• A deep furrow divides
the cerebrum into two
halves, known as the left
and right hemispheres.
Sometimes the right
hemisphere is
associated with creativity
and the left hemispheres
is associated with logic
abilities.
• The corpus callosum is a
bundle of axons which
connects these two
hemispheres.
Do Now!
1. What are the 4 parts of the cerebrum?
2. The convolutions of the cerebrum are comprised of
ridges and valleys. What are the ridges called? The
valleys?
3. What part of the brain is dedicated to visual
perceptions?
4. What part of the brain is associated with reasoning,
planning, parts of speech, movement, emotions, and
problem solving?
5. What part of the brain is associated with movement,
orientation, recognition, perception of stimuli?
6. What part of the brain is associated with perception
and recognition of auditory stimuli, memory, and
speech?
7. What is the deep furrow that divides the cerebrum into two
halves known as?
The Cerebellum
The cerebellum, or "little
brain", is similar to the
cerebrum in that it has
two hemispheres and
has a highly folded
surface or cortex.
CEREBELLUM: Located at the base of the skull, and attached to the
rear of the brain stem.
Functions:
Coordination of voluntary movement
posture
Balance and equilibrium
Some memory for reflex motor acts.
Limbic System:
•
•
The limbic system, often referred to as the "emotional
brain", is found buried within the cerebrum. Like the
cerebellum, evolutionarily the structure is rather old.
This system contains the:
1. thalamus (almost all sensory information enters this structure
where neurons send that information to the overlying cortex ),
2. hypothalamus (functions including homeostasis, emotion, thirst,
hunger, circadian rhythms, and control of the autonomic nervous
system. In addition, it controls the pituitary )
3. amygdala (memory, emotion, and fear ),
4. hippocampus (important for learning and memory, for converting
short term memory to more permanent memory, and for recalling
spatial relationships in the world about us)
Sense of smell
BRAIN STEM: Located deep in the brain, leads to spinal cord. Often referred to as
The 'Reptilian' or 'Primitive' Brain. The majority of the cranial nerves exit from the
brain stem at the pons.
The midbrain is the smallest region of
the brain that acts as a sort of relay
station for auditory and visual
information.
The pons connects the medulla to the
cerebellum and helps coordinate
movement on each side of the body.
The medulla is located directly above
the spinal cord and controls many vital
autonomic functions such as heart rate,
breathing and blood pressure.
Brain stem: 3 parts
• Lower animals
have only a
medulla.
• The brain stem
controls the
reflexes and
automatic
functions (heart
rate, blood
pressure), limb
movements and
visceral functions
(digestion,
urination).
Edheads.org
• Virtual brain surgery
Fissure: any cleft or groove,
normal or otherwise,
especially a deep fold in the
cerebral cortex involving its
entire thickness.
Sheep Brain Dissection
Guide
http://www.wellesley.edu/Biology/Concepts/Html/sheepbrain.html
http://academic.scranton.edu/department/psych/sheep/
Dura mater
Superior ID
After splitting the cerebral
hemispheres
Part 1: Sheep brain dissection
http://www.youtube.com/watch?v=y7gEWzPqm94
Ventral side of
the brain
Part 2: Brain dissection
http://www.youtube.com/watch?
v=jr3qSaUzc6Q
Here's the cerebellum pushed downward to
expose the superior and inferior colliculi and
pineal gland
The Superior
colliculus (2 parts)
and the inferior
colliculus (2 parts)
make up the
corpora
quadrigemina are
the reflex centers
involving hearing
and vision.
The Nerves
The largest nerve in
the body is the
sciatic and it splits
into the common
tibial and fibular
nerves that run down
each leg.
How the
messages
travel
• As part of the Peripheral Nervous System, nerves
reach from your brain to your face, ears, eyes, nose, and
spinal cord... and from the spinal cord to the rest of your
body.
1) Motor neurons (motoneurons) carry signals from the
central nervous system to the outer parts (muscles, skin,
glands) of your body.
2) Sensory neurons carry signals from the outer parts of
your body (periphery) into the central nervous system.
3) Receptors sense the environment (chemicals, light,
sound, touch) and encode this information into
electrochemical messages that are transmitted by
sensory neurons.
4) Interneurons connect various neurons within the brain
and spinal cord.
What’s a Reflex?
• You need to detect a change in the
environment (a stimulus) and react to the
change (a response) in a way that
maintains homeostasis.
• When you do this without thinking, it is
called a reflex.
Reflex Pathways
• The simplest type of neural pathway is a monosynaptic (single
connection) reflex pathway, like the knee-jerk reflex.
• 1. When the doctor taps the right spot on your knee with a
rubber hammer, receptors send a signal into the spinal cord
through a sensory neuron.
• 2. The sensory neuron passes the message to a motor neuron
that controls your leg muscles. Nerve impulses travel down the
motor neuron and stimulate the appropriate leg muscle to
contract.
• 3. The response is a muscular jerk that happens quickly and
does not involve your brain.
• Humans have lots of hard-wired reflexes like this, but as tasks
become more complex, the pathway "circuitry" gets more
complicated and the brain gets involved.
Revisiting the Knee-Jerk Response
What is the stimulus?
• The hammer hits the tendon.
What is the response?
• The muscle contracts, causing the foot to
jerk upward.
How is the Hammer Tap Detected?
• The muscles in your leg have
stretch receptors.
• They react to a change in length of
the muscle.
• When the hammer hits the tendon
at the knee, it makes a muscle in
the front of your thigh longer
(stretches it).
• That stimulates the stretch
receptors in that muscle.
Other Reflexes:
Stimulus
An insect flying towards your
eye
Response
Blinking
The aroma of your favorite food Salivation
A bright light shining in your
eye
Pupils get smaller
A nasty odor
Nausea
What detects the stimulus in each case?
Receptor Cells
The Response
• When the receptor is stimulated, it sends a
message to a part of your body that effects
the correct response.
• This is called the effector.
Reflex
arc
http://www.
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bio_07/g
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p.htm?ci
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animate
d_biolog
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How the Message Travels From the
Receptor to the Effector.
• A sensory neuron carries the message from the
receptor to the central nervous system (the spinal
cord and brain).
• A motor neuron carries the message from the
central nervous system to the effector.
• This is a reflex arc.
Motor (efferent) Neurons
• Is divided into two groups:
– 1. Autonomic system
– The ANS In most situations, we
are unaware of the workings of
the ANS because it functions in
an involuntary, reflexive manner.
2. Somatic system (back to this in a
moment)
Name the Neurons
• Neuron 2 ?
• Sensory Neuron
Name the Neurons
• Neuron 3 ?
• Interneuron
Name the Neurons
• Neuron 4 ?
• Motor Neuron
The ANS is most important in two
situations:
1.In emergencies that cause stress and require us to
"fight" or take "flight" (run away)
2.In non-emergencies that allow us to "rest" & "digest."
The ANS is divided into three parts:
1. The sympathetic nervous system
2. The parasympathetic nervous system
3. The enteric nervous system (is a meshwork of
nerve fibers that innervate the viscera (gastrointestinal
tract, pancreas, and gall bladder).
.
ANS •
• Sympathetic:
• These are "Fight or
Flight" responses. In
these types of situations,
your sympathetic nervous
system is called into
action - it uses energy your blood pressure
increases, your heart
beats faster, and
digestion slows down.
Parasympathetic
• This calls for "Rest and
Digest" responses. Now
is the time for the
parasympathetic nervous
to work to save energy your blood pressure
decreases, your heart
beats slower, and
digestion can start.
The Autonomic Nervous System
Structure
Sympathetic Stimulation
Parasympathetic Stimulation
Iris (eye muscle)
Pupil dilation
Pupil constriction
Salivary Glands
Saliva production reduced
Saliva production increased
Oral/Nasal
Mucosa
Mucus production reduced
Mucus production increased
Heart
Heart rate and force
increased
Heart rate and force decreased
Lung
Bronchial muscle relaxed
Bronchial muscle contracted
Stomach
Peristalsis reduced
Gastric juice secreted; motility
increased
Small Intestine
Motility reduced
Digestion increased
Large Intestine
Motility reduced
Secretions and motility increased
Liver
Increased conversion of
glycogen to glucose
Kidney
Decreased urine secretion
Adrenal medulla
Norepinephrine and
epinephrine secreted
Bladder
Wall relaxed
Sphincter closed
Increased urine secretion
Wall contracted
Sphincter relaxed
Back to
The Somatic Nervous System
• Somatic Nervous System
• The somatic nervous system consists of
peripheral nerve fibers that send sensory
information to the central nervous system AND
motor nerve fibers that project to skeletal
muscle.
• The picture shows the somatic motor system.
The cell body is located in either the brain or
spinal cord and projects directly to a skeletal
muscle.
This very strange
creature in the
Glasgow Science
Centre is the
Homunculus. The
different parts of
the body are sized
according to the
amount of nerves
present in that part
of the body.
Alzheimer’s disease:
• progressive degenerative
brain disease that results
in dementia associated
with a shortage of
acetylcholine (an
important
neurotransmitter) and
structural changes in brain
areas involving cognition
and memory. Because
nerve cells do not
undergo mitosis, new cells
can not be generated.
Aluminum and Alzheimer’s
Cerebrovascular accident (CVA):
• brain dysfunction
where blood
supply to a
region is blocked
and vital brain
tissues dies as
by a blood clot
or ruptured
blood vessel.
This is more
commonly called
a stroke.
Cerebral Edema
• a condition characterized by the presence of a
large amount of water in the brain.
• If not treated, it can be fatal, or cause severe
brain damage, and the quicker a patient is
treated, the better his or her chances of recovery
will be.
• Because this condition can be extremely
serious, evaluations to check for signs of
cerebral edema are common when patients are
brought in for head trauma, because doctors
want to catch it as early as possible.
Multiple sclerosis:
• when the myelin
sheath around
the axon
deteriorates the
electrical current
is short circuited.
• The person may
experience visual
and speech
disturbances and
also lose muscle
control.
M.S.
MS
• In multiple sclerosis, the myelin sheath is stripped off
from the neuron which considerably reduces the speed
of conduction of nerve transmissions. This process is
known as demyelination.
• The effects of this is to considerably slow down the
speed of nerve transmissions along the demyelinated
axons.
• The myelin is often laid down again in a repair process
known as remyelination which can often restore near
normal functioning to the axon.
• However, and particularly in progressive stages of the
disease, the myelin can be replaced with scar tissue or
the axonal body itself can be damaged.
Famous People with MS
Clive Burr - Iron Maiden Drummer
Alan Osmond
Annette Funicello –
singer, dancer, former
Mouseketeer
Danny Wallace –
Soccer Player
New Treatment:
Bee venom helps MS
• http://www.youtube.com/watch?v=7mbBIZ
HZ-yY
Wrist drop:
• The inability to extend the hand at the
wrist because the radial nerve has been
damaged.
Cerebral Edema
• The brain reacts to severe head trauma by
retaining water. As a result, the brain swells.
The pressure grows as the brain presses on
the skull. This can be fatal or result in
severe brain damage.
•
•
•
•
•
•
•
•
•
•
•
•
Wrist drop:
inability to extend the hand at the wrist because the radial nerve has been damaged.
Cerebral edema:
The brain reacts to severe head trauma by retaining water. As a result, the brain
swells. The pressure grows as the brain presses on the skull. This can be fatal or
result in brain damage.
Alzheimer’s disease:
progressive degenerative brain disease that results in dementia associated with a
shortage of acetylcholine (an important neurotransmitter) and structural changes in
brain areas involving cognition and memory. Because nerve cells do not undergo
mitosis, new cells can not be generated.
Cerebrovascular accident (CVA):
brain dysfunction where blood supply to a region is blocked and vital brain tissues
dies as by a blood clot or ruptured blood vessel. This is more commonly called a
stroke.
Multiple sclerosis:
when the myelin sheath around the axon deteriorates the electrical current is short
circuited. The person may experience visual and speech disturbances and also lose
muscle control.
FYI:
The largest nerve in the body is the ___________________ and it splits into the
common tibial and fibular nerves that run down each leg.
•Siatic nerve
The End
Complete your study guide to prepare for
the test.
 The test has….
 29 multiple choice (2 pts each)
 6 labeling neuron (2 points each)
 10 fill in the blanks (2 pts each)
 6 label parts of the brain
 100 points

Nervous System
Info on chemical on the nerves:
http://faculty.washington.edu/chu
dler/weap.html
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Chemical Weapons:
Nerve Agents
You may have read newspaper or magazine articles about the
possible use of chemicals during a war or a terrorist attack. Many of
these chemicals affect the nervous system and are therefore called
nerve agents.
Nerve agents are similar to insecticides and they can be deadly if
people are exposed to them.
Unfortunately, this has already happened. On March 20, 1995, twelve
people were killed and over 5,000 were injured when a nerve gas
called "sarin" was released in the Tokyo subway system.
People may have also been exposed to nerve agents during the
conflict ("Gulf War") in the Middle East. It is possible that many
countries have access to these dangerous weapons and future human
exposure to these chemicals is possible.
Breathing a lethal dose of these chemical can kill in 15 minutes; a
lethal dose on the skin (not much more than a single grain of rice!!)
can kill in only 1-2 minutes!! To get an idea of how deadly these
chemicals are, do the math.