What is a reflex?
Reveal answer
A rapid, automatic response that protects the body.
Key words: automatic
3(j) CO-ORDINATION AND RESPONSE · RECALL
3.40 A simple reflex arc
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Why are reflexes fast?
Reveal answer
Few neurones and synapses → no conscious decision.
Key words: conscious
Where does a withdrawal reflex arc pass?
Reveal answer
Through the spinal cord (relay neurone).
Key words: spinal cord
What is meant by the term reflex arc?
Reveal answer
Neural pathway producing a rapid automatic response.
Key words: reflex arc
What is meant by the term relay neurone?
Reveal answer
CNS neurone linking other neurones.
Key words: relay neurone
What is meant by the term automatic?
Reveal answer
Occurring without a conscious decision.
Key words: automatic
Withdrawal reflex sequence: for Heat/pain receptor, give the event and the direction/function.
Reveal answer
Event: Stimulus is transduced. Direction/function: Begins sensory signal.
Key words: Heat/pain receptor
Withdrawal reflex sequence: for Sensory neurone, give the event and the direction/function.
Reveal answer
Event: Impulse travels. Direction/function: Skin → spinal cord.
Key words: Sensory neurone
Withdrawal reflex sequence: for Relay neurone/synapses, give the event and the direction/function.
Reveal answer
Event: Signal crosses within CNS. Direction/function: Links input to output.
Key words: Relay neurone/synapses
Withdrawal reflex sequence: for Motor neurone, give the event and the direction/function.
Reveal answer
Event: Impulse travels. Direction/function: Spinal cord → muscle.
Key words: Motor neurone
Withdrawal reflex sequence: for Flexor muscle, give the event and the direction/function.
Reveal answer
Event: Contracts. Direction/function: Finger withdraws.
Key words: Flexor muscle
Withdrawal reflex sequence: for Brain pathway, give the event and the direction/function.
Reveal answer
Event: Information ascends. Direction/function: Conscious awareness.
Key words: Brain pathway
True or false, and why? “The brain is not involved at all in a reflex.”
Reveal answer
False. The spinal cord can initiate withdrawal, while information is also sent to the brain.
True or false, and why? “Reflexes are learned choices.”
Reveal answer
False. A simple withdrawal reflex is automatic and protective.
True or false, and why? “The sensory neurone connects directly to the muscle.”
Reveal answer
False. Motor neurones carry output to muscle after CNS relay/synapses.