DefinitionModerate1 mark
7(b)
Briefly explain the following terms:
Reflex action
Topic: Reflex action
Previous-year question practice database
Answer
Exam answer
A REFLEX ACTION is an automatic, quick and INVOLUNTARY response of the body to a stimulus, occurring without the conscious will of the individual.
Explanation
The essential words are AUTOMATIC, INVOLUNTARY and QUICK.
WHY IT IS SO FAST: the impulse takes the short route through the SPINAL CORD and back, instead of travelling up to the brain. That is the whole purpose — you pull your hand off a hot pan BEFORE you consciously feel the pain, and the brain is informed afterwards.
The pathway is the REFLEX ARC: receptor → sensory neuron → spinal cord → motor neuron → effector → response.
Example
Example: instantly withdrawing the hand on touching a hot object; blinking when something approaches the eye.
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