Download Human Biology - St Mary's College, Wallasey

24/05/2017
OCR Additional Science
Brain and Mind
A slideshow that covers the entire OCR
21st Century 2006 Syllabus “Brain and
Mind” Module
W Richards
The Weald School
The Nervous System
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The CENTRAL NERVOUS SYSTEM (CNS) enables us to react
to our surroundings. It consists mainly of the brain, the spinal
chord, nerve cells (“neurones”) and receptors.
Types of receptor:
1) Light receptors in the eyes
2) Sound receptors in the ears
3) Taste receptors on the tongue
4) Smell receptors in the nose
5) Touch, pressure and temperature receptors in the skin
6) Changes of position receptors in the ears (balance)
Nervous Reactions
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When we react to a stimulus our bodies use the following
pattern:
Stimulus
Receptor
For example, consider a
man and a camel:
Coordinator
Effector
Response
Oh
No!
What are the stimulus, receptor, coordinator, effector and
response in this situation?
Examples of reactions
Stimulus
Bright light
Sour taste
Losing balance
Sit on a drawing
pin
Receptor
(i.e. the thing
that detects the
stimulus)
Effector
(i.e. the thing
that will do the
reaction)
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Response
(i.e. action
taken)
Types of nerve cell (“neuron”)
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Nucleus
Axon
Fatty sheath
Muscle strands
(effector)
Nerve cells (neurons) are elongated with branched
endings to connect to many muscles fibres.
1) Motor neurone
2) Sensory neurone
Impulse
Impulse
3) Relay neurone
Synapses
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Neurones never ____ each other – there is a small gap
between them called a _____. A signal is sent from one
_______ to the next by a _______ transmitter across the
synapse (called a “neurotransmitter”). These transmitters are
then ________ back into the sensory neurone to be used
again. Children have around 1000 trillion synapses whereas
adults only have between 100 and 500 trillion.
Words – chemical, synapse, neurone, touch, reabsorbed
Conscious actions
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A conscious action is one where the brain makes a considered response.
Here’s what happens:
4) The brain
3) Here another sensory neurone
decides to move
carries the signal to the brain
away the hand
5) This impulse is
sent by MOTOR
NEURONES to the
hand muscles (the
effectors) via the
spinal chord…
2) The impulse is carried
by SENSORY NEURONES
to the spinal chord
1) Receptors in
your skin detect
a stimulus
Stimulus
6) Which then
moves the hand
away
Receptor
Motor Neurone
Sensory Neurone
Effector
Coordinator
Response
Reflex actions
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Sometimes conscious action is too slow to prevent harm, e.g…
In situations like this
the body bypasses the
brain to produce a
quicker response.
Here’s how it works…
Reflex actions
2. Sensory
neurone
1. Receptor
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3. Relay
neurone in the
spinal chord
4. Motor
neurone
5. Effector
Simple reflexes in humans
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Babies can demonstrate simple reflexes:
1) Stepping reflex
2) Startle (or moro) reflex
3) Grasping reflex
4) Rooting reflex
5) Sucking reflex
The Iris Reflex
When the light is bright
the radial muscles relax,
the circular muscles
contract and the pupil
increases in size.
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When the light is bright
the radial muscles _____,
the circular muscles
_______ and the pupil
________ in size.
Conditioned reflexes - Pavlov’s Dog
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I won the Nobel Prize in 1904 and am
most famous for investigating
“conditioned responses”:
Ivan Pavlov,
1849-1936
1) Steak + dog = saliva
2) Steak + bell + dog = saliva
3) Bell + dog = saliva
Complex Behaviour
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PET scan showing
areas “activated” by
doing algebra.
When the brain is asked to do certain tasks different areas
are “activated”. New experiences cause new neuron pathways
to develop, while pathways that are not used are eventually
destroyed. This is why we become better at certain tasks
when we practice them more often.
Feral children
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Task: to find out what “feral children” are, what has caused
their condition and what the consequences are.
The Cerebral Cortex
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By studying the effects (e.g. memory/sight loss) when
different parts of the brain are damaged scientists have been
able to identify which parts of the brain control which
functions.
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Other techniques of studying the brain
1) An electroencephalogram (EEG) is a
visual record of the electrical activity
generated by neurons in the brain. It
works by amplifying and detecting the
electrical signals from the brain.
2) Magnetic resonance imaging
(MRI) scanning is a new
technique that produces images
of different cross sections of
the brain and uses colours to
represent activity.
Memory
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Our memory is divided into two types: short term and long
term.
Short term memory is capable of storing a limited amount of
information for a limited amount of time. Long term memory
is when more information is stored over a much longer time.
Ways of improving
short term memory,
e.g. a phone number
Ways of improving
long term memory
e.g. exam revision
The Effect of Drugs
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Drugs can have different effects on the nervous system. For
example, alcohol _____ reactions down by affecting chemical
transmitters in the brain whereas caffeine causes nerve
impulses to be sent ______, thereby _______ reaction time.
Serotonin is a neurotransmitter in the central nervous system
that is associated with feeling ____. The drug ecstasy blocks
the synapses where the serotonin is removed, making the
feeling last longer. However, the neurons are harmed in this
process and taking ecstasy can lead to long term _____ loss.
Words – memory, slows, increasing, faster, happy
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Resources website.
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