The drug Viagra® counteracts the effects of NO on penile blood vessels.

a. True

b. False

Answer: False.

Explanation:

Viagra is a drugs use by men for the treatment of erectile dysfunction.

It works for men suffering from erectile dysfunction by increasing the blood flow to the penis, so that the man can have erection and have erection hard enough for sex.

False

Explanation:

Nitric Oxide (NO) plays an important role as a relaxant which enables blood vessels to dilate, hence increasing the flow of blood and further swelling of tissues. NO causes the penile tissue to relax, a further increase results to a fully erect penis. Therefor, penile erection depends on the increase of NO.

Viagra is used in erectile dysfunction. The active ingredient, slidenafil acts a phosphodiesterase type 5 inhibitor which increases the dilating ability of nitric oxide. This result to increased blood flow to tissues and further results to penile erection.

Therefore, Viagra does not counteract the effects of NO on penile blood vessels.