Anatomy And Physiology

Prostate Gland or Structure and Function of the Prostate Gland



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Prostate related problems have been the centre of attention in geriatric care pertaining to males. Its importance in the management of elderly males is due to several reasons. The position, the function and relatively common occurrence of age related disorders are some of these reasons.

1. Structure of the prostate

Prostate gland is part of the male reproductive tract and is located just underneath the bladder. It encircles the proximal part of the urethra which extends from the bladder neck to the end of the penis. The proximal part which surround the urethra appears round while the distal end is tapering and appears blunt.

The gland is of the size of a walnut and is approximately 20 cc in volume. It comprises 70% of glandular tissue and to an extent smooth muscle and fibrous tissues as well. It consist of 50-60 gland like structure which opens out to the ejaculatory ducts. Part of the urethra that is located within the prostate is known as the 'prostatic urethra' and two ejaculatory ducts opens in to this structure. The prostate is surrounded by a thick fibro-muscular layer.

The prostate enlargers till the puberty from birth and remain dormant till about 50 years of age. Thereafter, the prostate enlarges gradually and sometimes it can cause problems as well.

Structural explanation of the prostate gland can be done in two different ways. In one method the sections of the gland is identified as 'lobes' and in the other it is defined as 'zones'.

Classification according to lobes:

According to the anatomist the prostate gland comprises of 4 lobes

1. Anterior lobe

2. Posterior lobe

3. Lateral lobes

4. Median lobe

Classification according to zones:

According to the classification by zone, the structure is divided in to 4 zones

1. Peripheral zone

2. Central zone

3. Transitional zone

4. Fibro-muscular zone

The transitional zone or the anterior lobe is associated with the condition known as Benign Prostatic Hyperplasia where as the peripheral zone or the posterior lobe is commonly associated with cancers of the prostate gland.

The Fibro-muscular zone is actually a capsule which is rigid and prevents the prostate from expanding outwards.

2. Function of the prostate gland

The prostate acts as a storage facility to the seminal fluid which is partly secreted by the seminal vesicles. Seminal vesicles are closely related to the prostate and often involved with invasive prostate cancers.

a) The seminal fluid:

The prostate produces an alkaline secretion which will add volume to the seminal fluid. The alkaline fluid will act as a buffer in the vagina and prevents the semen from getting destroyed due to the acidic environment in the vagina. It also promoted the motility of the semen in reaching the fallopian tubes. Apart from the ability to act as a buffer it also contains enzymes, citric acid and calcium.

An enzyme in the prostatic fluid called 'prostate specific antigen' will act as a liquefaction agent once the seminal fluid has been ejaculated from the male reproductive tract. It will be released into the blood circulation in higher numbers in cancerous processes involving the prostate and can be used as a marker for prostate cancer.

The secretion of the prostatic fluid is influenced by the male sex hormones and mainly by testosterone.

b) Muscle contractions in male orgasm:

The smooth muscles which are present in the prostate contracts at the time of ejaculation and promote the propagation of semen and the seminal fluid along with the prostatic secretions. Being closer to the pelvic floor, its musculature will promote the ejaculatory process by contracting at the same time.

It is believed that the smooth muscles of the prostate will act as a sphincter and will prevent the urine from entering the urethra from the bladder at the time of ejaculation.

c) Prostate disorders:

Apart from Benign prostatic hyperplasia and cancers, another important functional and structural disorder in the prostate is the 'Prostatitis'. This is an inflammatory process and in some instances would require antibiotic treatment to relieve its symptoms.

In old age the prostate is a common site which can give rise to several problems. Most of these problems are treatable and early suspicion would promote early diagnosis of prostate cancers. In any event the problems related to prostate glands should be treated by an urologist.

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