Final answer:
All of the statements regarding erection are true. It involves parasympathetic stimulation, engorgement of erectile tissue, arterial dilation, and nitric oxide production, leading to an erection.
Step-by-step explanation:
The statement regarding erection that is true is E) All of the answers are correct. This physiological process involves parasympathetic stimulation of the penile arteries, leading to their dilation. It also includes vasocongestion, which is the engorgement of erectile tissue with blood. Additionally, nitric oxide (NO) production by neurons plays a crucial role in the vasodilation necessary to achieve an erection.
During sexual arousal or REM sleep, nitric oxide is released from nerve endings close to the blood vessels in the corpora cavernosa and spongiosum, which leads to the relaxation of the surrounding smooth muscles. As a result, the penile arteries dilate allowing more blood to enter the erectile tissues. This increased blood flow causes the erectile chambers to fill and compresses the penile venules, reducing venous drainage from the p_enis. The average length of an erect pen_is is approximately 15 cm, though this can vary based on individual flaccid dimensions.