The Function of the Prostate Gland

The prostate gland is a highly complex organ, the structure and functions of which is only partially understood. Primary prostate function is the production and delivery of semen, which serves as a medium for the delivery of sperm in reproductive activity. Because of its close proximity to the bladder and urethra, how the prostate works also directly affects the function of the male urinary system. Consequently, there is often a direct relationship between prostate health and quality of life for older men.

As shown in the adjacent prostate diagram, the prostate is located below the bladder, and surrounds the urethra at the point where this tube carries urine from the bladder to the penis. The normal prostate is usually about the size of a walnut, or about 3-5 centimeters in width.

Tubes attach the prostate to the seminal vesicles and, in turn, to the testicles, where sperm cells are generated. During sexual activity, sperm are carried from the testicles to the prostate, where they are mixed with prostate fluid and seminal vesicle fluid to form semen. During ejaculation, this material is squeezed into the urethra and out through the penis.

Prostate fluid is unusually rich in the minerals zinc and potassium, as well as citric acid and fructose. This fluid serves several functions in reproduction. In addition to serving as a medium for sperm delivery, it is thought to energize the sperm cells, and helps to make the vaginal canal less acidic.

Doctors refer to the prostate as comprised of several “zones”. The peripheral zone is the area that the doctor can feel with a finger inserted in the rectum (a digital rectal exam). This is also where nearly all prostate cancers begin. The transition zone is the area affected by enlarged prostate (BPH). While this zone nomally comprises less than 5% of the prostate’s volume, it can become much larger as the result of BPH. The central zone is where the seminal vesicles attach, and is rarely associated with any health problems.


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