Wikipedia

Prostate

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The prostate is an exocrine gland of the male mammalian reproductive system.

Prostate
Male Anatomy
Prostate with seminal vesicles and seminal ducts, viewed from in front and above.
Details
PrecursorEndodermic evaginations of the urethra
Arteryinternal pudendal artery, inferior vesical artery, and middle rectal artery
Veininternal iliac vein
Nerveinferior hypogastric plexus
Lymphexternal iliac lymph nodes, internal iliac lymph nodes
Identifiers
Latinprostata
MeSHD011467
TA98A09.3.08.001
TA23637
FMA9600
Anatomical terminology

The prostate differs considerably between species anatomically, chemically, and physiologically.

Relations

Function

The main function of the prostate is to store and secrete a clear, slightly alkaline fluid that constitutes up to one-third of the volume of semen. Semen is composed of spermatozoa 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 muscles that help expel semen during ejaculation.

Secretions

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. The secretions also contain zinc and citric acid.

Regulation

To work properly, the prostate needs male hormones (androgens), which 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.

Development

The prostate gland represents the modified wall of the proximal portion of the male urethra and develops by the 9th week of embryonic life. Condensation ofmesenchyme, urethra and Wolffian ducts gives rise to the adult prostate gland, a composite organ made up of several glandular and non-glandular components tightly fused within a common capsule.

Skene's glands found in many females are homologous to the prostate gland in males.

Structure

A healthy human prostate is slightly larger than a walnut. It surrounds the urethra just below the urinary bladder and can be felt during a rectal exam.

The ducts are lined with transitional epithelium.

Within the prostate, the urethra coming from the bladder is called the prostatic urethra and merges with the two ejaculatory ducts. (The male urethra has two functions: to carry urine from the bladder during urination and to carry semen during ejaculation.)

The prostate can be divided in two different ways: by zone, or by lobe.

Zones

The "zone" classification is more often used in pathology.

The prostate gland has four distinct glandular regions, two of which arise from different segments of the prostatic urethra:

Name Percent Description
The Peripheral Zone (PZ) Comprises up to 70% of the normal prostate gland in young men The sub-capsular portion of the posterior aspect of the prostate gland which surrounds the distal urethra. It is from this portion of the gland that more than 70% of prostatic cancers originate.
The Central Zone (CZ) Constitutes approximately 25% of the normal prostate gland This zone surrounds the ejaculatory ducts. Central zone tumours account for more than 25% of all prostate cancers.
The Transition Zone (TZ) Responsible for 5% of the prostate volume This zone is very rarely is associated with carcinoma. The transition zone surrounds the proximal urethra and is the region of the prostate gland which grows throughout life and is responsible for the disease of benign prostatic enlargement.
The Anterior Fibro-muscular zone (or stroma) Accounts for approximately 5% of the prostatic weight This zone is usually devoid of glandular components, and composed only, as its name suggests, of muscle and fibrous tissue.

Lobes

The "lobe" classification is more often used in gross anatomy.

anterior lobe (or isthmus) roughly corresponds to part of Transitional Zone
posterior lobe roughly corresponds to Peripheral Zone
lateral lobes spans all zones
median lobe (or middle lobe) roughly corresponds to part of Central Zone

Prostate disorders

Prostatitis

Prostatitis is inflammation of the prostate gland. There are different forms of prostatitis, each with different causes and outcomes. Acute prostatitis and chronic bacterial prostatitis are treated with antibiotics; chronic non-bacterial prostatitis or male chronic pelvic pain syndrome, which comprises about 95% of prostatitis diagnoses, is treated by a large variety of modalities including phytotherapy, alpha blockers, physical therapy, trigger point therapy, psychotherapy, antihistamines, anxiolytics, nerve modulators and more.[1] Benign prostatic hyperplasia (BPH) occurs in older men; the prostate often enlarges to the point where urination becomes difficult. 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. BPH 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. Older men often have corpora amylacea (amyloid), 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 BPH.

Prostate Cancer

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 older men to detect prostate cancer early. Research has shown that regular ("more than 5 times per week"[2]) masturbation can cut the risk of prostate cancer by up to a third. This is because it reduces the buildup of carconagenic deposits which can damage the cells lining the prostate.

Stimulation

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

Additional images

  •  
    Urinary bladder
  •  
    Structure of the penis
  •  
    Lobes of prostate
  •  
    Zones of prostate
  •  
    Prostate
  •  
    Prostate under a microscope This image shows the microscopic glands of the prostate
  • Male Anatomy
    Male Anatomy
  •  
    The deeper branches of the internal pudendal artery.
  •  
    Lymphatics of the prostate.
  •  
    Fundus of the bladder with the vesiculæ seminales.
  •  
    Vesiculae seminales and ampullae of ductus deferentes, seen from the front.
  •  
    Vertical section of bladder, penis, and urethra.

See also

References

The text of this article was originally taken from NIH Publication No. 02-4806, a public ___domain resource [1].

  1. ^ "Pharmacological treatment options for prostatitis/chronic pelvic pain syndrome" (html). 2006. Retrieved 2006-12-11.
  2. ^ http://news.bbc.co.uk/1/hi/health/3072021.stm
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