NEET · BiologyMedium
In the process of micturition, which of the following events occurs when the urinary bladder is filled with urine?
- A.Relaxation of the detrusor muscle and contraction of the internal urethral sphincter
- B.Contraction of the detrusor muscle and relaxation of the internal urethral sphincter
- C.Contraction of the external urethral sphincter and relaxation of the detrusor muscle
- D.Relaxation of both the internal and external urethral sphincters without detrusor activity
Show correct answer & step-by-step solution
Correct answer: B — Contraction of the detrusor muscle and relaxation of the internal urethral sphincter
Solution
- Stretch receptors in the bladder wall are activated by filling.
- Signals are sent to the central nervous system to initiate the micturition reflex.
- The reflex causes the detrusor muscle to contract.
- Simultaneously, the internal urethral sphincter relaxes to allow urine flow.
- Hence the answer is (B).
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