Anatomy And Physiology

Anatomy Physiology



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The prostate gland is an accessory sex gland in males. It is situated below the bladder and around the the urethra. The prostate gland is divided anatomically to four areas or zones. The outer most zone is called the peripheral zone. It constitutes approximately 70% of the total weight of the gland.

The peripheral zone is responsible for the origin of cancer in the prostate gland. In addition, this area is also vulnerable to inflammation which afflicts the gland. The physician can palpitate and feel this zone of the gland during normal rectal examination.

The next inner zone near to the peripheral zone is called the central zone. Its mass is around a quarter or 25% of the mass of the prostate gland. This area is not susceptible to inflammation and to malignancy. Next to the central zone of the prostate gland from the inner side is the transitional zone. It contains glands that are called mucosal glands.

This area of the gland is responsible for the clinical condition that is called benign prostatic hyperplasia. This condition is especially important in old people. The cells of this part of the gland undergo proliferation which is called medically hyperplasia. This hyperplasia or enlargement of the gland compresses the urethra. Thus leading to obstruction of the urine outflow from the bladder.

The last area or zone of the gland and which is the innermost part is called the periurethral zone. This zone or area of the gland contains two types of glands. These are mucosal and submucosal glands. Hyperplasia of this area along with the hyperplasia of the transitional zone contribute to the medical condition benign prostatic hyperplasia.

The prostate gland secretes many compounds that are found in the seminal fluid. Some of these compounds are two important enzymes that are called prostate specific antigen and prostate acid phosphatase. In prostate carcinoma the secretion of these two hormones is elevated. Thus their concentration in the blood is a marker for prostate malignancy.

In addition to these two enzymes, the prostate gland secretes also fibrinolysin and citric acid. Fibrinolysin functions by liquefying the seminal fluid. Citric acid is an important intermediate in the krebs cycle for the generation of the energy rich molecule ATP.

The two most important medical conditions that affect the prostate gland are benign prostatic hyperplasia and prostatic carcinoma. Benign prostatic hyperplasia is thought to be a direct result of the testosterone metabolite DHT or dihydrotestosterone. This metabolite is thought to be responsible for the hyperplasia of the prostate gland. It stimulates the prostatic cells to proliferate.

Dihydrotestosterone is synthesized from testosterone by the action of the enzyme 5 alpha reductase which catalyze this reaction. Therefore inhibition of the action of this enzyme constitute a treatment to this clinical condition. Administration of medications such as doxazosin and dutasteride which are inhibitors of 5 alpha reductase constitute a treatment to this condition. In addition surgery to remove part of the gland is another alternative to medications.

Prostatic cancer is directly related to testosterone production. Testosterone stimulates the proliferation of cancer cells of the prostate. Therefore treatment to this condition constitutes removal of the testis in order to minimize the testosterone secretion by the testis. In addition the treatment with medications such as cyproterone and estrogens constitute another treatment for this condition.

The symptoms that are associated with prostatic diseases include enlargement of the gland due to several causes such as benign prostatic hyperplasia which can cause acute urine retention in the bladder that is associated with painful dilatation of the bladder wall. Alternatively chronic urine retention can occur and which is typified by incomplete emptying of the bladder content.

In this case also the bladder can be dilated and the cells of its wall undergo hypertrophy. Due to the incomplete voiding of the urine a predisposition to infection occurs. As a result of the urinary retention, renal failure can occur due to hydroureter or and hydronephrosis.

Another symptom that is usually associated with prostatic disease is pain which is associated is felt when urinating or upon ejection.

Another symptom of prostatic disease is passing bloody urine or hematuria. It can occur in benign prostatic hyperplasia. In addition hematuria is a manifestation of late prostatic carcinoma which is often caused in the peripheral zone of the gland.

Two types of prostatic diseases are acute and chronic prostatitis. Both of these conditions are common. Acute prostatitis is often caused by gram negative bacteria and in particular E. coli. It is often formed as a complication of lower urinary tract infection. Clinically, it is manifested by pain upon urination or ejaculation. Chronic prostatitis is also caused by bacteria, and it is found enlarged upon examination.

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