Download File

Functions of the central
nervous system CNS
For your information
• THE FUNCTIONS OF THE BRAIN
– The human brain is a complex organ that allows us to
think, move, feel, see, hear, taste, and smell. It
controls our body, receives information, analyzes
information, and stores information (our memories).
The brain produces electrical signals, which, together
with chemical reactions, let the parts of the body
communicate. Nerves send these signals throughout
the body.
Did you know?...
• Your brain uses 20% of your body's energy, but it makes
up only 2% of your body's weight.
• Your brain is about 1300-1400 cubic centimeters in
volume, about the size of a cantaloupe and wrinkled like
a walnut.
• The brain feels like a ripe avocado and looks pink
because of the blood flowing through it.
• Your brain generates 25 watts of power while you're
awake---enough to illuminate a lighbulb.
• A newborn baby's brain grows almost 3 times in course
of first year
• Humans have the most complex brain of any animal on
earth.
• Your brain is divided into two sides. The left side of your
brain controls the right side of your body; and, the right
side of your brain controls the left side of your body.
CNS=central nervous system
•
Central Nervous System (CNS)
Introduction:
– Radiates throughout the body
– Controls all body organs
– Regulates all conscious and unconscious
actions
CNS=central nervous system
A. Main parts of the CNS:
1. BRAIN (cerebrum, cerebellum, brainstem)

Hard drive of a computer where data is analyzed and
stored
2. SPINAL CORD

Computer processor (pentium, intel centrino duo)
3. NERVES

“wires” that carry messages to & from the brain
C.N.S.
B. Anatomy of a neuron
The brain is made up of millions of
individual cells called neurons.
•
Neurons have specialized parts with
specialized functions:
A. Dendrites
B. Cell body (nucleus)
C. Axon
D. Axon Terminals
Anatomy of a neuron
Dendrites
• these are branched processes specialized
to receive input and carry information
toward the cell body
The cell body
• is the metabolic center of the neuron
(where energy is made)
• contains the nucleus (center) of the cell
• most proteins needed for functioning are
made here
• incoming signals from dendrites meet here
Anatomy of a neuron
Axon
• is larger in diameter than dendrites
• is specialized to carry information
away from the cell body
• may be very long, up to 1 m
Axon Terminals
• the end of the axon
• Sends the signal on to other neurons
Draw your own picture of a neuron
here and label the 4 parts
A real neuron
Review questions
1) What does the CNS stand for?
2) What are the three main parts of the CNS
and what are their main functions?
3) What is the brain made up of?
4) What are the 4 main parts of the neuron
and what are their specialized functions?
Answers to review questions
1) What does the CNS stand for?
Central Nervous System
2) What are the three main parts of the CNS and
what are their main functions?
Brain: analyses and stores information
Spinal Cord: processes the information
Nerves: carry messages to and from the brain
3) What is the brain made up of?
Millions of cells called neurons
Answers to review questions
4) What are the 4 main parts of the neuron and
what are their specialized functions?
Dendrites: receive inputs from other neurons
and carry messages to towards the cell body
Cell body: Makes energy and proteins for the
neuron, processes the inputs from the dendrites
Axon: transmits the nerve impulse away from
the cell body
Axon terminals: relays (passes on) the nerve
impulse to another neuron
How do neurons communicate?
• The connection between two neurons is called a
synapse
• Neurons interact with other neurons through
synapses
•  the axon terminals of one neuron will end
near the dendrites of another neuron
• the Presynaptic neuron: sends out information
• the Postsynaptic neuron: receives information
• note: There is no physical connection between
the two neurons
Nerve impulses
When a neuron registers an external or internal stimulus
(such as a sound, light, touch, odour) it will produce an
electric current known as a nerve impulse or an action
potential (AP).
For one neuron to send an impulse to another, it
secretes a chemical messenger called a
neurotransmitter (NT) into the gap (synaptic cleft)
between it and the next neuron
It will then transmit the impulse (or AP) to different
organs of the body
(animation- NIDA brain addiction)
Fill in the blanks with the following words:
relayed, received, transmitted, processed,
Nerve impulses are:
1) _____________by the dendrites
2) _____________ by the cell body
3) _____________ through the axon
4) _____________ by the axon terminals
Fill in the blanks with the following words:
relayed, received, transmitted, processed,
Nerve impulses are:
1) received by the dendrites
2) processed by the cell body
3) transmitted through the axon
4) relayed by the axon terminals
 passed on to the next neuron
Neurons interact with other
neurons by synapses
Nerves
• A collection of neuronal axons forms a
nerve.
• Many nerves radiate throughout the body,
making it possible for nerve impulses to
reach all parts of the body
• There are two main categories of nerves:
– Sensory nerves
– Motor nerves
Motor vs. Sensory Nerves
Sensory nerves send
information from the
sensory organs to the
brain
Motor nerves send
information from the brain
to the muscles
synapse
synapse
vertebrae
Motor nerve: Start: brain, end: muscle
Sensory nerve: Start: sense receptor, end: brain
Review Questions
1) What is a synapse?
2) Draw a picture of a synapse including pre and
postsynaptic neurons. Make sure to label all structures
in your diagram.
3) What are two names for the electric current that travels
down a neuron?
4) What is the name of the chemical messengers found at
inside the axon terminal?
5) What part of the neuron receives the nerve impulse?
6) What is a nerve?
7) What two types of nerves exist and what are 2
differences between them?
1)
2)
3)
4)
5)
6)
Neuron 1  C
Neuron 4  D
Neuron 3  B
Neuron 2  A
Neuron 5  F
Neuron 6  E
Answers to review questions
1) What is a synapse?
The connection between 2 neurons
through which they interact
2) Draw a picture of a synapse including pre
and postsynaptic neurons. Make sure to
label all structures in your diagram.
Answers to review questions
3) What are two names for the electric current that
travels down a neuron?
- Nerve impulse, action potential
4) What is the name of the chemical messengers
found at inside the axon terminal?
- neurotransmitters
5) What part of the neuron receives the nerve
impulse?
- the dendrite
6) What is a nerve?
- a collection of neurons
Answers to review questions
7) What two types of nerves exist and what are 2
differences between them?
- sensory nerves: - bring information from the
sense receptors to the brain
- send sensory signals to the
brain
- motor nerves: - bring information from the
brain down to the muscles
- allow you to move
PBS clip: From Zzzz’s to A’s.
http://www.pbs.org/wgbh/pages/frontline/sho
ws/teenbrain/view/
1. How many hours of sleep to you need to get in order to
be fully alert?
2. What is the name of your Biological Timing System and
how does it change during the teenage years?
3. What analogy does the announcer use for a teen that is
trying to function with not enough sleep?
4. What are three daily life functions that sleep affects your
ability to do?
5. What is REM sleep and what happens during this time?
6. What is the best predictor of whether or not you will
succeed at school?
7. What were the results of the study of the relationship
between learning and sleep in teens Charlie and Nicole?
From Zzzz’s to A’s (clip)
1.
How many hours of sleep to you need to get in order to be fully alert?
9¼
2. What is the name of your Biological Timing System and how does it change
during the teenage years?
The circadian clock: it shifts forwards (in the day) during the teenage years
3. What analogy does the announcer use for a teen that is trying to function
with not enough sleep?
It’s like a car trying to run on an empty tank.
4. What are three daily life functions that sleep affects your ability to do?
Your mood, your ability to think and your ability to perform and react
appropriately.
5. What is REM sleep and what happens during this time?
Rapid Eye Movement. Dreaming and learning happens during this time.
6. What is the best predictor of whether or not you will succeed at school?
Whether or not you get a good night’s sleep.
7. What were the results of the study of the relationship between learning and
sleep in teens Charlie and Nicole?
Nicole got more REM sleep than did Charlie and she also improved more
on the learning tasks than Charlie did. Thus, the more REM sleep you get
the better you learn.
Nova on Sleep
• Brain Trauma
Consequences of damage to nerve cells
A. The nerve cell does not regenerate
itself
B. The transmission of impulses may
diminish or stop
C. Interpretation of the impulse may be
distorted, interrupted, or only partially
completed
Damage to the C.N.S.





Concussion: temporary, hit to the head, may
produce unconsciousness or bleeding in or around
the brain.
Paralysis: injury to the spinal cord
Cerebral palsy: lack of muscle control due to brain
damage before or soon after birth
Epilepsy: muscular seizures and body convulsions
caused by abnormal action potentials
Multiple sclerosis: hardening of the nerve tissue in
the brain or spinal cord
What happened to Phineas Gage?
Reading
Questions
1) How did Phineas Gage change after the
accident?
Gage’s personality changed. He was no longer the
likable and respectable person he was before the
accident. Instead he was irresponsible and used
foul language.
2) How did Phineas Gage’s accident change
scientists’ understanding of the brain?
Scientists learned that the brain does more than
control the language and movement. It controls
emotions and social behaviors.
Scientists also learned that specific parts of the
brain control specific functions
The moral of the story is….
Different parts of your brain control
different senses and emotions
Lobes of the brain
Name of lobe
Function
Lobes of the brain
Name of lobe
Function
Occipital lobe
“command center” =
decision making
Processes vision
Parietal lobe
Analyses sensation
Temporal lobe
Hearing, understanding speech
and integrating all senses
Frontal lobe
Probe the Brain
• Beginning in the 1940s,
Canadian brain surgeon Wilder
Penfield mapped the brain's
motor cortex -- the area that
controls the movement of your
body's muscles.
• He did this by applying mild
electric currents to the exposed
brains of patients while they
were in surgery.
• Brain Probing Activity
Other roles of the nervous system
A. Site of the intellectual processes
 Mostly found in the frontal lobe of the brain
B. Reflex centre
 The spinal cord serves as the body’s reflex
centre
 Reflex = an involuntary act that results when a
nerve impulse is sent out by the spinal cord in
response to an unexpected stimulus.
You accidentally touch the burner
on your stove at home….
What happens?
You automatically pull your hand away
HOW DOES THIS HAPPEN?
Reflex Response
1)
The touch receptors in your hand relay information to
the spinal cord in the form of a nerve impulse
2)
BUT this nerve impulse doesn’t get send to the brain.
WHY?
- Because it would take too long and this situation is
urgent
3) Instead, a nerve impulse is commanded from the spinal
cord to the hand muscles, telling them to draw away
- Processing the information at level of the spinal cord
instead of the brain allows the response to occur faster
Reflex animation
Knee-jerk reflex
Ways to improve the power of your brain…
(or, how to become more intelligent)
Lead a balanced lifestyle by:
A. Eating a Proper diet:
The nervous system needs a regular supply of B vitamins
because these vitamins:
- strengthen the neurons
- facilitate the transmission of nerve impulses
Foods that are rich in B vitamins are:
- egg yolks, milk, whole grain cereals, fresh meat
B. Exercise regularly
The brain needs 20% of the body’s oxygen to function
properly, so it’s important for your circulatory system be
in tip-top shape. You can achieve this by exercising on a
regular basis.
C. Get enough sleep
While you sleep your neurons reset themselves and
prepare for a new day of activity.
If the body does not get enough sleep:
– Intellectual performance will be impaired
– Reflexes slow down
– It becomes difficult to concentrate
Review Questions
1)
2)
3)
4)
5)
6)
7)
What did the study of Phineas Gage teach us about
the brain?
What lobe of the brain processes vision?
Who is Wilder Penfield and how did he contribute to
our understanding of the brain?
Where is the site of intellectual processes in the brain?
What 3 types of neurons are involved in reflex
responses and in what order do nerve impulses travel
through them?
What is the difference between a voluntary movement
such as walking and an involuntary movement such as
a reflex response?
What 3 things can you do to improve the power of you
brain?
Answers
1) What did the study of Phineas Gage teach us about the brain?
- that the brain is not only responsible for language and movement
but it is also responsible for determining one’s emotions and
personality
2) What lobe of the brain processes vision?
The occipital lobe
3) Who is Wilder Penfield and how did he contribute to our understanding of
the brain?
- He was a brain surgeon who made of map of the motor cortex
(which regions control which body parts)
4) Where is the site of intellectual processes in the brain?
Frontal cortex
Answers to class starter questions
5)
What 3 types of neurons are involved in reflex responses and in
what order do nerve impulses travel through them?
1- Sensory neuron, 2- interneuron 3- Motor neuron
6)
What is the difference between a voluntary movement such as
walking and an involuntary movement such as a reflex response?
Voluntary movements get processed by the brain whereas
involuntary movements only get sent to the spinal cord and don’t
reach the brain
7)
What 3 things can you do to improve the power of you brain?
Maintain a healthy diet rich in B vitamins, exercise regularly, and
get enough sleep (9 ¼ hours/ night)
• Unit test on the CNS on Tuesday
• Pages 1,2,3,7 of drugs package