Question

What effect does the sympathetic nervous system have on micturition?

1) Sympathetic activity excites muscles of the internal urethral sphincter inhibiting micturition.
2) Sympathetic activity inhibits muscles of the internal urethral sphincter inhibiting micturition.
3) Sympathetic activity excites muscles of the external urethral sphincter allowing micturition.
4) Sympathetic activity inhibits muscles of the external urethral sphincter inhibiting micturition.
5) Sympathetic activity excites muscles of the internal urethral sphincter allowing micturition.

Answer 1

Sympathetic nervous system activity leads to the excitation of the internal urethral sphincter muscles, thereby inhibiting micturition by preventing urine from leaving the bladder.

Step-by-step explanation:

The effect of the sympathetic nervous system on micturition is to inhibit the process. Specifically, sympathetic activity excites the muscles of the internal urethral sphincter, which inhibits micturition. During this process, the sympathetic nerves via the hypogastric nerves suppress the contraction of the bladder's detrusor muscle. While the detrusor muscle is relaxed, the internal urethral sphincter is contracted, preventing the voiding of urine. Therefore, the correct statement in the context provided is: 1) Sympathetic activity excites muscles of the internal urethral sphincter inhibiting micturition.

Normal micturition is controlled by a balance between the sympathetic and parasympathetic systems, and the somatic nerves that control the external urethral sphincter. Under sympathetic control, the muscles of the internal urethral sphincter remain constricted to retain urine in the bladder.