Once the male body gets sexually excited or the mind goes into sexual thoughts the male reproductive part penis gets an ERECTION, as the result of a physiological phenomenon. When the body gets sexually stimulated blood flows into the penis. Excitements give muscular relaxation to the penis and allow blood to enter penile arteries. There are two chambers in penis Known as corpora cavernosa. However, when chambers get filled with blood the penile structure gets rigid causing erection which makes human male capable to make an intercourse. The duration of sexual intercourse is highly dependent on the way your penile structure maintain its rigidness. But due to some reasons, people face an erection problem. Medically it is termed as erectile dysfunction.