A student's pupil immediately becomes smaller in bright light. What is the correct control pathway in this response?
Answer and explanation
Correct answer: Photoreceptor to nerve message to brain to eye muscle
The governing concept is nervous control of the pupillary light reflex. Photoreceptors in the retina detect intense light and generate nerve impulses. These signals travel through the optic pathway to the brain, which sends motor instructions to the iris muscles; the circular muscles contract and the pupil becomes smaller. Hence option A is correct. The other pathways use unrelated organs or an unsuitable hormonal route.
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What is the correct answer to this question?
Photoreceptor to nerve message to brain to eye muscle
Why is this the correct answer?
The governing concept is nervous control of the pupillary light reflex. Photoreceptors in the retina detect intense light and generate nerve impulses. These signals travel through the optic pathway to the brain, which sends motor instructions to the iris muscles; the circular muscles contract and the pupil becomes smaller. Hence option A is correct. The other pathways use unrelated organs or an unsuitable hormonal route.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Control and Coordination. Topic: Nervous system.
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