The Human Brain

1
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
The brain
The Human Brain
Often, human brains are checked for signs of
disease!
Once the person doesnt need it anymore, of
course!
This is often done at a post mortem (autopsy)
If you want to look at some really advanced brain
research methods, click here. Its interesting
but it wont be in the exam
2
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
Reflexes pass through the spinal cord and are
fast and automatic
Reflex actions often involve three neurones
sensory, relay and motor.
sensory neurone
relay neurone
Typical brain cell (type of relay neurone)
motor neurone
3
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Motor and sensory neurones
What is the function of the cytoplasm in the cell
body?
Where most of the chemical reactions of the cell
take place
How can you tell a motor neurone from a sensory
neurone?
The motor neurone has its main cell body at one
end. Which is which here?
? neurone
sensory neurone
? neurone
motor neurone
What is the function of the fatty layer (myelin
sheath)
It acts as an electrical insulator so that nerve
carry impulses faster
What is the dendrite function?
They make contact with other nerve cells
What is the function of the nerve endings?
They stimulate muscles or glands
4
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
Impulses from a _____________pass along a sensory
neurone to the CNS
receptor
At the junction between the sensory and relay
neurone in the CNS a ____________ is released
which causes an impulse in the relay neurone
chemical
transmitter
transmitter
nerve impulse
nerve impulse
Relay neurone
Sensory neurone
motor neurone
Effector (muscle or gland)
Receptor
The _____________ then releases a chemical,
stimulating the motor neurone
relay neurone
The _______ is either a muscle (contracts) or
gland (secretes a chemical).
effector
The motor neurone stimulates a ________ to
contract or a _________ to secrete. Muscles and
glands are called ______________
gland
muscle
effector
5
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
Impulses from a receptor pass along a sensory
neurone to the CNS
At the junction between the sensory and relay
neurone in the CNS a chemical is released which
causes an impulse in the relay neurone
transmitter
transmitter
nerve impulse
nerve impulse
Relay neurone
Sensory neurone
motor neurone
Effector (muscle or gland)
Receptor
The relay neurone then releases a chemical,
stimulating the motor neurone
The effector is either a muscle (contracts) or
gland (secretes a chemical).
The motor neurone stimulates a muscle to contract
or a gland to secrete
6
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
sensory
relay
motor
The 3 nerves involved in the reflex arc
Pain in the skin causes an arm muscle to contract
to withdraw the hand
Cross section of the spinal cord
7
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
1 of 13
SHARP OBJECT
sensory
relay
motor
Skin Pain receptors generate a nerve impulse in
the sensory neurone
8
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
2 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the sensory
neurone
9
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
3 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the sensory
neurone
10
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
4 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the sensory
neurone
11
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
5 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the sensory
neurone
12
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
6 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the sensory
neurone
13
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
7 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the sensory
neurone
14
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
8 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the relay neurone
15
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
9 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the motor neurone
16
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
10 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the motor neurone
17
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
11 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the motor neurone
18
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
12 of 13
SHARP OBJECT
sensory
relay
motor
The nerve impulse travels along the motor neurone
19
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex arcs
A hand withdrawal reflex
Sequence
13 of 13
SHARP OBJECT
RE-RUN
sensory
relay
motor
MUSCLE CONTRACTS
The impulse causes the muscle to contract
20
IGCSE BIOLOGY CO-ORDINATED RESPONSE
SENSE ORGANS
ANTAGONISTIC MUSCLES
II.10 NERVOUS CONTROL
NERVOUS SYSTEM
THE EYE
ROUND UP
NERVES REFLEX ARCS
Reflex analysis
21
IGCSE BIOLOGY CO-ORDINATED RESPONSE
II.10 NERVOUS CONTROL
Transmitter chemicals and synapses
When an impulse arrives at the end of a nerve a
transmitter chemical is released
nerve impulse
transmitter
nerve impulse
Sensory neurone
Relay neurone
synapse
Sequence
1 of 8