The prostate gland is an important part of the male reproductive system. The prostate is a gland situated between the bladder and penis, just in front of the rectum, or lower end of the bowel. The urethra, a narrow tube that carries urine and semen out of the body through the penis, runs through the center of the prostate, which is about the size of a walnut and weighs 1 ounce (30 grams). The word “prostate” comes from the Greek word “prostates,” which means “one who stands before,” aptly describing the position of the gland. That is, when viewed from below, the prostate “stands before” the bladder.
The Function of the Prostate
The prostate gland isn’t essential for life, but it is vital for reproduction and is part of the male reproductive system. The function of the prostate is to produce a slightly alkaline (high pH) fluid that makes up part of the seminal fluid, or semen. The rest of semen is composed of sperm cells from the testicles, fluid from the seminal vesicles, and secretions from the pea-sized bulbourethral gland.
The prostatic fluid contains substances that are important to the functioning and survival of sperm cells, such as the enzyme prostate-specific antigen (PSA), which thins or loosens up semen, helping the tadpole-like sperm cells swim freely to reach the egg. During an orgasm, prostate muscles squeeze the gland’s stored fluid into the urethra, where it mixes with the sperm cells and other semen components. This expulsive process also helps propel the semen out of the body during ejaculation.