Navigation Links
Semen


Semen or ejaculate is the fluid discharged from the penis during ejaculation, usually at the time of orgasm. Like blood, semen consists of two compartments, the cellular compartment (spermatozoa) and noncellular compartment (seminal plasma). It contains the sperm, which sometimes results in pregnancy following vaginal sex with a female. Semen is a whitish, milky fluid, very viscous, containing water and small amounts of salt, protein, and fructose.

Contents

Composition

Around 200 million to 500 million spermatozoa (or 'sperm', for short), produced in the testes, are released per ejaculation. However, they make up only about 2–5% of the volume of semen. The bulk of the semen is composed of seminal plasma, the fluid portion of semen.This fluid is contributed by the accessory male reproductive organs . Some 60% of the volume of ejaculate is produced by the seminal vesicles, and most of the remainder is generated by the prostate. A small amount of viscous mucus secreted by the bulbourethral glands contributes to the cohesive jelly-like texture of semen.

Seminal plasma of humans contains a complex range of organic and inorganic constituents. They include metal and salt ions, sugars, lipids, steroid hormones, enzymes, prostaglandin hormones, amino acids and basic amines. The purpose of the seminal plasma is to provide a nutritive and protective medium for the spermatozoa during their journey through the female reproductive tract. The normal enviroment of the vagina is a hostile one for sperm cells, it is very acidic (from the native microflora producing lactic acid), viscous, and patrolled by immune cells. The components in the seminal plasma attempt to compensate for this hostile enviroment.

Basic amines such as putrescine, spermine , spermidine and cadaverine are responsible for the smell and flavor of semen. These alkaline bases counteract the acidic environment of the vaginal canal (which is harmful to sperm), and protect DNA inside the sperm from acidic denaturation. Salts and metal ions in the semen help to create a more hospitable enviroment for the sperm in the vaginal canal. A typical ejaculation can contain up to 5 mg of zinc. Zinc serves to help to stabilize the DNA containing chromatin in the sperm cells. A zinc deficiency may result in lowered fertility because of increased sperm fragility. Zinc deficiency can also adversely affect spermatogenesis.

The simple sugar fructose is the main energy source of sperm cells, which rely entirely on sugars from the seminal plasma for energy. Other components of semen (mucus and texturizing proteins) serve to increase the mobility of sperm cells in the vagina and cervix by creating a less viscous channel for the sperm cells to swim though, and preventing their diffusion out of the semen. Prostaglandin hormones are involved in supressing an immune response by the female against the foreign semen.

Semen and transmission of disease

Semen is in itself harmless on the skin or if swallowed. However, semen can be the vehicle for many sexually transmitted diseases, including HIV, the virus that causes AIDS. It is also hypothesized that components of semen, such as the spermatozoa as well as the seminal plasma, can cause immunosuppression in the body when introduced to the bloodstream or lymph. Evidence for this dates back to 1898, when Elie Metchnikoff injected a guinea pig with its own and foreign guinea pig sperm, finding that an antibody was produced in response; however the antibody was inactive, pointing to a suppression response by the immune system. Further research, such as that by S. Mathur and J.M. Goust, demonstrated that non-preexisting antibodies were produced in humans in response to the sperm. These antibodies mistakenly recognized native T lymphocytes as foreign antigens, and consequently the T lymphyocytes would fall under attack by the body's B lymphocytes .

Other semen components shown to spur an immunosuppressive effect are seminal plasma and seminal lymphocytes. Note that any kind of sexual or other skin contact with the semen of a person infected with HIV should be avoided, even by persons already infected with the virus, as this may cause harmful re-infection.

Cultural views

In some cultures, semen is attributed with special properties of masculinity. For instance, among the Etoro people of Papua New Guinea, it is believed that young boys must fellate their elders and ingest their sperm to achieve proper sexual maturation. Other cultures believe semen to have beneficial qualities when applied to the skin, mainly for cosmetic purposes.

See also

References

External links


'"/>


(Date:7/30/2014)... DURHAM, N.C. -- A study of dominance in female baboons ... maintain close ties with mom, and to have lots of ... not by size or strength, but by the rank of ... higher-ranked her daughter will be. For this reason, dominance rank ... Females born to high-ranking mothers are guaranteed a good spot ...
(Date:7/30/2014)... University associate professor Andrew S. Mount, performed cutting-edge research ... for novel anti-fouling paint for ships and boats and ... The team,s findings, published in Nature Communications ... that attaches to a wide variety of surfaces using ... an underwater heavy-duty adhesive. , "In previous research, we ...
(Date:7/30/2014)... July 30, 2014 ResearchMoz ... Government Biometric Systems Market 2014-2024   Business Strategies, Industry ... Biometric Systems Market 2014-2024" offers the reader detailed ... the next ten years, alongside potential market opportunities ... forecasts. To view the table of ...
Breaking Biology News(10 mins):Supportive moms and sisters boost female baboon's rank 2Supportive moms and sisters boost female baboon's rank 3Study: Marine pest provides advances in maritime anti-fouling and biomedicine 2Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 2Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 3Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 4Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 5Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 6Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 7Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 8Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 9Global Government Biometric Systems Market Size, Share, Trends and Forecasts 2014-2024 Available Online by Researchmoz.us 10
... in the Asian tsunami tragedy should be allowed to ... according to some of the world's leading scientists. , ... of Newcastle upon Tyne, and who set out their ... point to historical records of major coral reef devastation ...
... U.S. ports, a public enemy has infiltrated the nation's borders. ... Cornell University expert, the adult female alien is the only ... States. , The discovery of a single specimen of Sirex ... the nation because the invasive insect species has devastated up ...
... strains of leprosy-causing bacteria has revealed some surprises about ... across the continents by human migrations. The research, led ... in the 13 May issue of the journal Science, ... findings indicate that the world's existing leprosy infections are ...
Cached Biology News:Tsunami-damaged coral reefs should be left to recover naturally, say scientists 2Alien woodwasp, threat to US pine trees, found in N.Y. 2Leprosy genome tells story of human migrations, French researchers report in Science 2Leprosy genome tells story of human migrations, French researchers report in Science 3
Other biology definitionOther Tags