Select the correct answers to the questions from the given options. (Do not copy the questions, write the correct answer only.)
Bharat woke up late in the morning and missed the school bus. This situation stimulated the nerves of the sympathetic system which resulted in:
Topic: Sympathetic nervous system — fight-or-flight
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Pick an option and check your answer. The full worked answer is below either way.
Answer
(d) Bronchodilation.
The sympathetic nervous system produces the FIGHT-OR-FLIGHT response — it prepares the body for sudden action. Ask of each option: would this help someone about to run?
(D) BRONCHODILATION — the bronchi widen, so more air reaches the lungs and more oxygen enters the blood. Exactly what a runner needs. CORRECT. (A) Constriction of coronary arteries — the opposite happens. The coronary arteries DILATE, so the heart muscle itself gets more blood. (B) Muscle relaxation — skeletal muscles receive MORE blood and are readied for action, not relaxed. (C) Decrease in heart rate — the heart rate RISES.
THE SINGLE TEST that answers every sympathetic-system question: does the change help you fight or run? If yes, the sympathetic system does it. Heart rate up, breathing up, pupils dilated, blood diverted to muscles, digestion slowed.
The PARASYMPATHETIC system does the reverse — "rest and digest" — slowing the heart, constricting the pupils and stimulating digestion.
Bronchodilation.