About the prostate

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A virtual section through the body showing the prostate and surrounding structures

The prostate is the shape and size of a walnut and is located low down in the pelvis, at the base of the bladder. It starts life as a tiny gland, whose growth and development at puberty are influenced by the male hormone, testosterone, secreted from the pubertal testis.

The role of the prostate is to produce a nutritious fluid that mixes with the ejaculated sperm at orgasm and nourishes the sperm on their journey. The prostatic secretion makes up the majority volume of the ejaculate. One protein produced by the prostate – Prostate Specific Antigen (PSA) – not only occurs in the ejaculate but also appears in the bloodstream – where it is measurable. Blood levels of PSA increase in benign hypertrophy and in prostate cancer.

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Detailed section through the body showing the prostate

The main function of PSA is to clear away the residual matter left within the prostatic ducts after orgasm – if left alone, this debris would solidify and block them. The action by which the enzymes in PSA dissolve and remove this debris is termed ‘protease activity’. In other words, the enzymatic activity of PSA keeps the system clean. The level of PSA normally present in the bloodstream reflects the activity and health of the prostate gland. This can be measured by a PSA test.

Prostate growth continues with the years, and enlargement of the gland may be such that it can cause significant difficulties. In particular, the gland’s physical location may lead to problems with urination. When you urinate, urine flows from the bladder along a tube called the urethra, which passes through the centre of the prostate before leaving the body via the penis. The flow of urine is controlled by valves, which are opened and closed at will on urination. However, the neck of the bladder may be obstructed by a large prostate, causing difficulty in urine flow.