How does a man achieve an erection?

Posted on 02. Mar, 2009 by Mel G in Sexuality

: Image via Wikipedia

An erection is the result of a combination of both physical and psychological stimulation that are started with nervous responses between the brain and the muscles.

Various neurotransmitters in the brain create nerve impulses that then trigger the muscles in the penis that control blood flow into the Corpous Cavernosa.
These muscles relax, allowing large amounts of blood to flow into the penis. The spaces in the Corpous Cavernosa then fill with blood.

Both physical and mental arousal also causes nerve activity that tells the vascular system to increase blood flow to the penis.

The two main arteries in the penis pump in more blood, creating pressure that inflates it to form an erection. As the penis needs to retain the blood to remain erect, each body of erectile tissue is surrounded by an elastic membrane – the tunicae – which hold the blood from leaving the penis. This is what allows the penis to become inflated.

After stimulation is over or following ejaculation, these reactions reversed. The pressure in the penis is reduced as the tunicae loosen and the smooth muscle in the blood vessels contract.

This stops the inflow of blood, and opens the veins for the blood to flow back out. The penis then contracts back to its flaccid state.