Prostate Gland
The prostate gland is found in the pelvis. Specifically, it lies beneath the bladder surrounding a tube
(the urethra) as it exits the bladder. The urethra is responsible in transporting urine from the bladder to
the outside world. The prostate gland is approximately the size of a walnut, about one and a half inches
long. Initially very small, the prostate is stimulated to grow at puberty, due the rising levels of the
hormone testosterone, to a volume of about 20 cc.
The prostate is subdivided into three zones: central, transition and peripheral. This subdivision is
relevant. Benign prostatic hyperplasia commonly affects the transition zone that can lead to the
narrowing of the urethra. Prostate cancer and prostatitis are usually found in the peripheral zone.
The main function of the prostate gland is during ejaculation. Sperm are stored in a jelly-like matrix. At
the time of ejaculation sperm are mixed with fluid from the prostate gland as it contracts. A substance
released by the prostate called Prostate Specific Antigen (PSA) liquidises the ejaculate in order to
improve the chances of fertilization. The fluid produced by the prostate also prevents infection in the
urethra.
