What is the effect of increased sympathetic tone on the erectile tissue of the penis?

What is the effect of increased sympathetic tone on the erectile tissue of the penis?

• A. Stimulates erection
• B. No effect
• C. Inhibits erection (correct)
• D. Causes venous outflow

Answer: (C)

Erection depends on parasympathetic activity releasing nitric oxide that relaxes smooth muscle in the erectile tissue, allowing arterial inflow to fill the corpora cavernosa and compressing venous outflow to sustain the erection. Increased sympathetic tone does the opposite: it contracts the smooth muscle of the penile arteries and the trabecular smooth muscle, reducing arterial inflow and promoting venous drainage. The net result is detumescence, i.e., inhibition of erection.

Erection depends on parasympathetic activity releasing nitric oxide that relaxes smooth muscle in the erectile tissue, allowing arterial inflow to fill the corpora cavernosa and compressing venous outflow to sustain the erection. Increased sympathetic tone does the opposite: it contracts the smooth muscle of the penile arteries and the trabecular smooth muscle, reducing arterial inflow and promoting venous drainage. The net result is detumescence, i.e., inhibition of erection.