Which of the following is correct regarding the neural mechanism underlying bladder voiding?

Options:
explanation: This is incorrect. The external urethral sphincter (the skeletal muscle sphincter) is under somatic control. To cause the sphincter to relax, somatic activity must be decreased, not increased. For bladder voiding to take place, several changes occur: Sympathetic activity to the internal urethral sphincter (a smooth muscle sphincter) is reduced, causing it to relax. Somatic activity to the external urethra sphincter (a skeletal muscle sphincter under voluntary control) is also reduced, again causing it to relax. Finally, parasympathetic activation of the detrusor muscle in the bladder wall is increased, causing bladder contraction.
name: Somatic activity in the bladder is increased causing relaxation of the skeletal muscle sphincter
label: e
answer: no
explanation: This is incorrect. The parasympathetic nervous system does not innervate the internal urethral sphincter (the smooth muscle sphincter), it controls detrusor contraction. For bladder voiding to take place, several changes occur: Sympathetic activity to the internal urethral sphincter (a smooth muscle sphincter) is reduced, causing it to relax. Somatic activity to the external urethra sphincter (a skeletal muscle sphincter under voluntary control) is also reduced, again causing it to relax. Finally, parasympathetic activation of the detrusor muscle in the bladder wall is increased, causing bladder contraction.
name: Parasympathetic activity to the bladder is reduced causing relaxation of the smooth muscle sphincter
label: c
answer: no
explanation: This is incorrect. Sympathetic innervation of the internal urethral sphincter (the smooth muscle sphincter) acts to maintain contraction. To relax the sphincter, sympathetic activity must reduce. Alongside this, somatic activity to the external urethra sphincter (a skeletal muscle sphincter under voluntary control) is also reduced, again causing it to relax. Finally, parasympathetic activation of the detrusor muscle in the bladder wall is increased, causing bladder contraction.
name: Sympathetic activity to the bladder is increased causing relaxation of the smooth muscle sphincter
label: b
answer: no
explanation: This is incorrect. To initiate detrusor contraction, parasympathetic activity must increase, not decrease. For bladder voiding to take place, several changes occur: Sympathetic activity to the internal urethral sphincter (a smooth muscle sphincter) is reduced, causing it to relax. Somatic activity to the external urethra sphincter (a skeletal muscle sphincter under voluntary control) is also reduced, again causing it to relax. Finally, parasympathetic activation of the detrusor muscle in the bladder wall is increased, causing bladder contraction.
name: Parasympathetic activity to the bladder is reduced causing contraction of the detrusor muscle
label: d
answer: no
explanation: This is correct. For bladder voiding to take place, several changes occur: Sympathetic activity to the internal urethral sphincter (a smooth muscle sphincter) is reduced, causing it to relax. Somatic activity to the external urethra sphincter (a skeletal muscle sphincter under voluntary control) is also reduced, again causing it to relax. Finally, parasympathetic activation of the detrusor muscle in the bladder wall is increased, causing bladder contraction.
name: Sympathetic activity to the bladder is reduced causing relaxation of the smooth muscle sphincter
label: a
answer: yes

Correct answer: a