Student centered study on understanding the CNS

1. The Human Nervous System
Leader Martin
24 June 25

2. The Nervous System has TWO Major
Divisions.
• The Central Nervous System
• The Peripheral Nervous System

3. The Central Nervous System
(CNS)
• The Central Nervous System (CNS)
consist of the Brain and the Spinal Cord.
• The spinal cord carries messages from the
body to the brain, where they are analyzed
and interpreted.
• Response messages are then passed
from the brain through the spinal cord and
to the rest of the body.
• Both the brain and the spinal cord are
encased in bone.

4. Brain
• One of the most active organs of the human
body
• The brain receives 20% of the blood that is
pumped from the heart
• Brain and spinal cord float in a fluid known as
cerebrospinal fluid.
– This fluid cushions against shock.
• Major parts of the Brain:
– Cerebrum (Cerebral Cortex)
– Cerebellum
– Medulla Oblongata

6. • Thalamus – relay
center between Brain
and spinal cord
• Hypothalamus –
controls body
temperature, blood
pressure, and emotions
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7. Cerebral cortex
• 3 major Functions
– Sensory areas that receive impulses from sense
receptors (Eyes, ears, taste, nose, pain, pressure,
heat/cold, touch)
– Motor areas that start impulses that are responsible
for all voluntary movement
– Associative areas of the brain are responsible for
memory, learning and thought
• The cerebral cortex has many folds called
convolutions
• Convolutions – are folds on the brain that
increase surface area

9. The Cerebellum
• Controls all voluntary movements and
some involuntary
• The cerebellum helps with balance, rate of
muscle contraction, and the muscles
position in relation to gravity
• Allows for smooth orderly movement
• Also plays a role in sensory perception to
maintain balance (inner ear)

11. Medulla Oblongata
• Connect the spinal
cord to all other parts
of the brain
• Control involuntary
activities
– Breathing
– Heartbeat
– Blood flow
– coughing

12. Memory
• Scientist do not know exactly how
memories are created
• 3 types of memory
– Momentary – lasts a few min
– Short-term – Several hours
– Long-term – Weeks to years and longer
• How memories change from short-term to
long-term is unknown

13. THE SPINAL CORD
• 2 Important Functions
– Connects the nerves
of the peripheral
nervous system with
the brain
– Controls certain
reflexes which are
automatic responses
• The spinal cord is
continuous with the
brain and emerges
from an opening at the
base of the skull.

14. The Peripheral Nervous System
(PNS)
• The Peripheral Nervous System (PNS)
consists of the neurons NOT Included in
the brain and spinal cord.
– AFFERENT NEURONS - Peripheral Neurons
collect information from the body and transmit
it TOWARD the CNS (sensory)
– EFFERENT NEURONS. - Peripheral Neurons
transmit information AWAY from the CNS
(motor)

16. Divisions of the Peripheral Nervous
System
• Somatic Nervous System – This system is
responsible for body movements over
which the individual has some conscious
awareness or voluntary control
• Autonomic Nervous System – This system
is responsible for involuntary activities.
– 2 divisions
• Sympathetic
• Parasympathetic

17. THE SOMATIC NERVOUS
SYSTEM
• Regulates activities that ARE UNDER
CONSCIOUS CONTROL, movement of
skeletal muscles.
– Every time you lift your finger or wiggle your
toes, you are using the motor neurons of the
Somatic Nervous System.
nerve cell animation
• Many nerves within this system are part of
reflexes and can act automatically.

18. THE AUTONOMIC NERVOUS
SYSTEM
• Regulates ACTIVITIES THAT ARE
AUTOMATIC, OR INVOLUNTARY.
• The nerves of the Autonomic Nervous System
control functions of the body that are NOT
UNDER CONSCIOUS CONTROL.
• MAINTAINING HOMEOSTASIS IN THE
FUNCTIONING OF MANY ORGANS OF THE
BODY.
– Examples: heart rate, breathing rate, digestion
salivation ect. . . .

19. THE AUTONOMIC NERVOUS SYSTEM IS
SUBDIVIDED INTO TWO PARTS:

20. Sympathetic “Fight or Flight”
Nervous System
• The sympathetic nervous system prepares the body for
sudden stress
– For example if you see a robbery taking place.
• When something frightening happens, the sympathetic
nervous system takes over
– makes the heart beat faster
– diverts blood to your muscles and chest
– makes the pupils dilate
– causes the adrenal glands at the top of the kidneys to release
adrenaline, to give extra power to the muscles for a quick
getaway.
• This process is known as the body's "fight or flight"
response.
• http://www.youtube.com/watch?v=LjX88mkzU4g&safety_
mode=true&persist_safety_mode=1

21. Parasympathetic “Sit and Digest”
nervous system
• It prepares the body for rest.
• Slows heart rate
• It also helps the digestive tract move along
so our bodies can efficiently take in
nutrients from the food we eat.
• Opposite of the sympathetic

22. REFLEXES
• A reflex is an
involuntary response to
a STIMULUS.
• Reflexes are very fast,
and Most Reflexes
Never Reach the
Brain.
• The reflex arc is an
automatic, involuntary
reaction to a stimulus.
When the doctor taps
your knee with the
rubber hammer, she/he
is testing your reflex (or
knee-jerk). Reflex Arc