What is the effect of increased sympathetic tone on the bladder?

What is the effect of increased sympathetic tone on the bladder?

• A. Increases sphincter tone and incomplete emptying (correct)
• B. Decreases sphincter tone
• C. Increases detrusor contraction
• D. Promotes micturition

Answer: (A)

When the bladder is under sympathetic control, the body is in storage mode. Norepinephrine from the hypogastric nerves stimulates the internal urethral sphincter to contract (via alpha-1 receptors) and relaxes the detrusor muscle (via beta receptors). This combination tightens the outlet and prevents strong bladder contractions, leading to incomplete emptying and urine retention rather than voiding. The other effects—decreased sphincter tone, increased detrusor contraction, or promoted micturition—are characteristic of parasympathetic predominance, which occurs during the voiding phase.

When the bladder is under sympathetic control, the body is in storage mode. Norepinephrine from the hypogastric nerves stimulates the internal urethral sphincter to contract (via alpha-1 receptors) and relaxes the detrusor muscle (via beta receptors). This combination tightens the outlet and prevents strong bladder contractions, leading to incomplete emptying and urine retention rather than voiding. The other effects—decreased sphincter tone, increased detrusor contraction, or promoted micturition—are characteristic of parasympathetic predominance, which occurs during the voiding phase.