How does an erection occur?
Many different events have to take place before an erection occurs with the penis. The first thing to trigger the chain of events is called psychosexual stimulation. This occurs when the libido, also known as the male sex drive, is stimulated, promoting the psychosexual stimulation. The brain sends impulses down the nervous system to the penis, relaxing the smooth muscles of the arteries that supply blood to the penis. This muscle relaxation causes the engorgement and erection of the penis, and helps it stay erect throughout intercourse until orgasm. After a man reaches orgasm, the blood retreats and returns to circulation, and the penis slowly returns to its normal, flaccid state. With so many different events triggering an erection for sexual activity, any disturbance of any one of these events could cause erectile dysfunction, such as disturbances of the nerve triggers, decreased blood supply, or problems with the psychosexual stimulation.
