The prostate gland
The prostate gland is an organ composed of smooth muscle and secretory glands which lies at the base of the bladder. It is pierced by two tubes which meet beneath the prostate: from back to front by the ejaculatory duct, through which semen is expelled during climax; and vertically by the urethra, which drains urine from the bladder to the outside world.
Continence
Continence (the ability to retain urine without leakage) is maintained by two valves: the internal ‘sphincter’ or valve (at the top of the prostate gland), which is weak and is not essential, and by the external sphincter (below the prostate gland), which is powerful. A weak external sphincter can be helped to close by a strong pelvic floor, which surrounds it, by squeezing it closed.
Function of the Prostate Gland
Its purpose is to add secretions to semen, which is stored ready for ejaculation in the seminal vesicles behind the prostate and zinc to the urine, which helps to suppress urinary infection.
Size of the Prostate Gland
The prostate gland commonly enlarges with age but a widespread misconception is that an enlarged prostate causes problems with urination, whereas a prostate which is not enlarged does not. In reality, tiny prostates (20 ml) can cause severe obstruction to the flow of urine from the bladder if their shape kinks the urethra, just as very large prostates (200 ml) can sometimes cause no symptoms whatever. In general, the prostate gland increases in size with age but this is by no means inevitable. An average prostate has a volume of 30-40 ml.
Prostate problems
Problems related to the prostate are very common and become commoner with increasing age.
