Question

During micturition

• A. Urethra relaxes
• B. Ureter contracts
• C. Ureter relaxes
• D. Urethra contracts

Answer 1

Answer: (A)

The process of urination is coordinated by the micturition reflex, which involves both involuntary and voluntary mechanisms. Involuntary control is by stretch receptors in the wall of the bladder, which become stimulated as the bladder distends (approximately 500 ml of urine). Once these receptors have become stimulated, the smooth muscle of the bladder contracts. These contractions elevate fluid pressure within the bladder. If both external and internal urethral sphincters are relaxed, urine is ejected. The external sphincter is relaxed under voluntary control.

So, the correct answer is option A.