2. 1. Functions of the nervous system
There are three major functions of the
nervous system
• Sensory - to receive information about the
internal and external environment of the
body.
• control- to analyse sensory information,
store information and make decisions.
• motor- to send messages to muscles or gland
in response to stimuli.
3. 2. Organisation of the nervous
system
The nervous system has two main parts.
• The central nervous system which consist of
the
– brain
– spinal cord
• nerves/neurones which connect the CNS to
all parts of the body.
4. 3. Function of the CNS
The CNS sorts out stimuli received from the
sense organs and sends messages to those
muscles which can make the appropriate
response.
stimulus
Sense
organ
CNS
Muscle
or gland
response
Motor
nerve
Sensory
nerve
5. 4. Nerves
Nerves are bundles of nerve cells called
neurones which are the longest cells of the
body.
Sensory neurones carry messages from
receptors in the sense organs towards the
CNS.
Motor neurones carry messages from the CNS
to the muscles/glands.
6. 4. Nerves
In the CNS there are shorter interconnecting
nerve cells called inter neurones which
connect sensory neurones to motor neurones.
The interaction of these neurones can be seen
in reflex actions.
7. Synapse
• Where two neurones meet,
there is a tiny gap called a
synapse. Electrical impulses
cross this gap using chemicals.
One neurone releases the
chemical into the gap. The
chemical diffuses across the
gap and makes the next
neurone transmit an electrical
signal.
8. The human body contains up to 500 trillion synapses.
Neurone 1
Neurone 2
9. When a nerve impulse arrives at the end of one neurone
it triggers the release of chemicals from synaptic
vesicles. The chemicals diffuse across
the synaptic gap
synaptic
vesicle
chemicals
10. Once across the synaptic gap the chemicals bind with
receptors on the next neurone, triggering the next
electrical impulse.
electric
impulse
receptor
synaptic
gap
11. Reflex action
• A reflex action is a rapid,
involuntary, protective
response. Reflex
reactions are not under
conscious control and take
place to keep the body
from harm.
12. Reflex action
• A potentially dangerous
stimulus triggers nerve
endings in a sense organ (eye,
ear, tongue, skin or nose).
An impulse is sent along a
sensory neurone then along
an inter neurone in the spinal
cord. The impulse is then
passed along a motor neurone
to an effector (a muscle or
gland) causing a response e.g.
muscle contraction or
hormone secretion.
14. 1. If the hand touches something very
hot the receptors in the skin detect
the pain.
2. An impulse travels from the receptor
along the sensory neurone to the spinal
cord
Inter
15. 3. An inter neurone connects the sensory
neurone to the motor neurone – the
reflex arc.
4. An impulse leaves the spinal cord in
the motor neurone nerve and travels
to the muscle.
16. 3. The muscle responds by contracting
and the hand is removed from danger.
22. The brain
• The human brain is an extremely complex organ
made up of hundreds of billions of nerve cells.
• The brain can be divided into a number of
regions.
• Side view of the brain seen in mid vertical
section (slice down the
middle)
Albert Einstein’s Brain
23. Why is the brain enclosed by our
skull?
The cranium
consists of 8
bones.
Suture
25. The cerebrum
• Makes up 85% of the brain's
weight.
• Controls conscious thought,
thinking, emotions and
intelligence.
• The cerebrum has two halves, with one on
either side of the head.
• Involved in both short and long term memory.
29. Long term memory
• Capacity is unknown.
•Information is
thought to be stored
permanently.
30. The cerebellum
• The cerebellum is at the
back of the brain, below
the cerebrum.
• Roughly 1/8 of the size of
the cerebrum.
• Controls balance,
movement, and
coordination.
31. The Medulla
• Site of involuntary
responses e.g. heart rate,
breathing, reflexes etc.
32. The brain
Name of Area Function
Cerebrum
Controls conscious thought,
thinking, emotions and
intelligence
Cerebellum
Controls muscle
coordination and balance
Medulla
Controls unconscious
activities e.g. heart
rate, breathing,
peristalsis
33. How is your short term memory
doing??
• How many objects can you
remember from earlier?
34. Tasks
• Count the F’s
There are 6. The brain does not register the F in
OF. To count 3 is normal.
FINISHED FILES ARE THE RE
SULT OF YEARS OF SCIENTI
FIC STUDY COMBINED WITH
THE EXPERIENCE OF YEARS...
47. Tasks…
1. Memory game
2. Try your Sudoku puzzle
3. Brain past paper questions.
http://www.bbc.co.uk/scotland/brainsmar
t/
48. How is your short term memory
doing??
• How many objects can you
remember from yesterday?
49. Tasks…
1. Model brain for display.
2. Brain past paper questions.
3. Test your memory:
http://www.bbc.co.uk/scotland/brainsmart/
Extension: Find out about Alzheimer's
disease.
