The prostate is a gland -- about the size of a walnut -- located below the bladder, and surrounding the upper part of the tube that transports urine and expels it from the body, called the urethra. In cases when a tumor forms in the prostate, the prostate gland can actually prevent or reduce the flow of urine from the body.
The prostate gland is an important part of the male reproductive system, producing and storing the fluid that helps create semen. It is influenced by the male hormones found within the body. These include a number of hormones produced by the adrenal glands, and testosterone, a hormone produced in the testicles.