How does an erection form?

In its relaxed state, the penis is relatively small and hangs limply. When fully erect, the diameter swells and the shaft grows to a significant length. The mind is the trigger. When it understands the situation is one where sexual stimulation is occurring, it sends a message to the smooth muscles in the walls of the arteries leading into the penis. The instruction is “simple”. It is to dilate the arteries. At rest, the main stream of blood flowing around the body passes by the penis. But when the arteries dilate, blood flows into the penis.

The central core of the penis is called the corpus cavernosum. It is designed to act like a sponge and swells when more blood flows in. As this core swells, it pinches the dorsal veins and restricts the flow of blood out. With an increasing amount of blood trapped inside the penis, it grows into an erect state.

How does an erection end?

In sexual intercourse, a hard erection allows penetration and mutual stimulation until orgasm or some other event prevents completion of the sexual act. The process for reducing the erection requires a reversal of the sequence. Thus, arteries that dilated must now contract. This cuts off the flow of blood into the corpus cavernosum. Once this happens, the blood starts to drain out of the spongy tissue which in turn releases the pressure on the veins. With the veins free, blood flows out more rapidly and the penis returns to its resting state. The trigger for the contraction of the arteries is the release of nitric oxide into the blood stream.

What goes wrong?

In physical terms, the most common cause of erectile dysfunction is the premature release of nitric oxide into the blood stream. The earlier in the sequence of events this happens, the more rapidly the erection collapses. Indeed, if everything is out of sequence, the erection fails to form or collapses almost as soon as it forms. It should be said there are other physical and psychological causes of erectile dysfunction. Cialis can help with some but not all these causes.

How does cialis work?

The messenger the brain sends to the part of the human chemical factory instructing it to release nitric oxide into the blood stream is one of the phosphodiesterases. There are twelve different uses for this messenger chemical and type 5 (PDE 5) is specific to the penis. Cialis is designed to prevent the release of PDE 5. Thus, no nitric oxide is released into the blood stream and the penis remains erect until orgasm. This leaves a naturally formed erection with full hardness until sexual activity is complete.