비아그라에 대한 5가지 쉬운 사실 설명

Sexual stimulation that brings about an erection results in the generation and release of nitric oxide during the penis. Nitric oxide triggers an enzyme, guanylate cyclase, to supply cyclic guanosine monophosphate (cGMP) which is primarily accountable for raising and decreasing the size of blood vessels carrying blood to and through the penis and t