Prostate

From Free net encyclopedia

The prostate is an exocrine gland of the male mammalian reproductive system. Its main function is to secrete and store a clear, slightly basic fluid that constitutes up to one-third of the volume of semen. The prostate differs considerably between species anatomically, chemically, and physiologically. A healthy human prostate is slightly larger than a walnut. It surrounds the urethra just below the urinary bladder. It is located in front of the rectum and can be felt during a rectal exam.

The male urethra has two functions: to carry urine from the bladder during urination and to carry semen during ejaculation. Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts. Semen is composed of sperm and seminal fluid; about 10-30% of the seminal fluid is produced by the prostate gland, the rest is produced by the two seminal vesicles. The prostate also contains some smooth muscle that helps to expel semen during ejaculation.

Prostatic secretions vary between species. They are generally composed of simple sugars, and are often slightly basic. In human prostatic secretions, the protein content is less than 1% and includes proteolytic enzymes, acid phosphatase, and prostate-specific antigen. Its secretions also contain zinc and citric acid.

To work properly, the prostate needs male hormones (androgens). Male hormones are responsible for male sex characteristics. The main male hormone is testosterone, which is produced mainly by the testicles. Some male hormones are produced in small amounts by the adrenal glands.

Prostate glands are found only in males; Skene's glands in females are homologous to the prostate gland in males.

1 Structure
2 Disorders of the prostate
3 Stimulation
4 See also
5 External links

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Structure

The prostate gland develops as a series of evaginations of the endodermal urethra, forming 30-50 tubuloacinar exocrine glands. Each gland is composed of simple columnar or pseudostratified columnar epithelium and empties via branched ducts into the prostatic urethra. The entire organ is encapsulated by a fibrous capsule.

Older men often possess corpora amylacea, dense accumulations of calcified proteinaceous material, in the ducts of their prostates. The corpora amylacea may obstruct the lumens of the prostatic ducts, and may underlie some cases of benign prostatic hyperplasia.

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Disorders of the prostate

Image:Prostatehistology.jpg Inflammation of the prostate gland is known as prostatitis. If the prostate grows too large it may constrict the urethra and impede the flow of urine, making urination difficult and painful and in extreme cases completely impossible. Prostatitis is treated with antibiotics, prostate massage or surgery.

In older men, the prostate often enlarges to the point where urination becomes difficult. This is known as benign prostatic hyperplasia and can be treated with medication or with surgery that removes part of the prostate. The surgery most often used in such cases is called transurethral resection of the prostate (TURP or TUR). In TURP, an instrument is inserted through the urethra to remove prostate tissue that is pressing against the upper part of the urethra and restricting the flow of urine.

Prostate cancer is one of the most common cancers affecting elderly men in developed countries and a major cause of death. Regular rectal exams are recommended for elderly men to detect prostate cancer early. There is also a blood test that measures the concentration of a protein, Prostate Specific Antigen (PSA), which is normally very low. Elevated test results may be an indicator of disorder within the prostate, either prostatitis, benign hyperplasia or prostate cancer. The PSA test cannot distinguish between them, but can lead a doctor to investigate further. Prostate cancer is treated with hormone manipulation (prevention of production of testosterone), radiation and/or surgery. It has recently been found that the drug Docetaxel can be effective in the treatment of prostate cancer.

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Stimulation

Stimulation of the prostate gland in males has been compared to stimulation of the Grafenberg spot in females in that prostate stimulation can result in a more powerful orgasm. See Prostate massage for more information.

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External links

prostate cancer treatment and support group
Active Sex Life Seen as Protecting Prostate from NPR.org
"What I need to know about prostate problems" by the US National Institutes of Health.
Prostate Cancer Symptoms & Treatments
Prostate Disease and Prostate Cancer Guide
3D Representation of male sexual organs, with links to information on Prostate Cancer from the UK based Prostate Cancer Charity
"Drug hope in prostate cancer care", from BBC News
Us TOO International Prostate Cancer Education and Support Network
Prostate Troubles Info on Prostate Cancer, other Prostate Problems and the latest Prostate News
The Male G Spot Info on prostate stimulation and sexual pleasure
Prostate-Help Gateway A non-commercial group of websites, chats, discussion groups, database, blogs, all on prostate cancer - all for your use and free to all.

Reproductive system - edit
Female - Cervix \| Clitoris \| Clitoral hood \| Fallopian tubes \| Bartholin's glands \| G-spot \| Hymen \| Labium \| Mammary glands \| Ovaries \| Skene's glands \| Urethra \| Uterus \| Vagina \| Vulva
Male - Urethra \| Testes \| Scrotum \| Spermatic cord \| Epididymis \| Seminiferous tubules \| Sertoli cell \| Rete testis \| Efferent ducts \| Vas deferens \| Seminal vesicles \| Ejaculatory duct \| Penis \| Corpus cavernosum \| Glans penis \| Fundiform ligament \| Foreskin \| Frenulum \| Prostate \| Bulbourethral glands