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Semen

This article is about male ejaculatory fluid. For {{{2|other uses}}}, see {{{3|Semen (disambiguation)}}}.

Semen or sperm is a fluidthat contains spermatozoa. It is secreted by the gonads(sexual glands) of maleor hermaphroditicanimals, including humans, for fertilizationof femaleova. Semen discharged by an animal or human is known as ejaculate, and the process of discharge is called ejaculation. Like blood, semen consists of two parts, the cellularpart (spermatozoa) and noncellular part (seminal plasma).

Depending on the speciesof animals, spermatozoa can fertilize ova externally or internally. In external fertilization, the spermatozoa fertilize the ova directly, outside of the female's sexual organs. Female fish, for example, spawnova into their aquatic environment, where they are fertilized by the semen of the male fish.

During internal fertilization, however, fertilization occurs inside the female's sexual organs. Internal fertilization takes places after inseminationof a female by a male through copulation. In low vertebrates(amphibians, reptiles, birdsand monotrememammals), copulation is achieved through the physical mating of the cloacaof the male and female. In marsupialand placental mammals, copulation occurs through the vagina.

Mammalian semen is a whitish, milkyfluid, very viscous, containing waterand small amounts of salt,vitamin D, protein, and fructose. The plasma portion of semen may contain dissolved water- and fat-soluble constituents, depending on the diet of the organism in question. These constituents may affect the color, odor, consistency, and taste of the semen.

Inhaltsverzeichnis

  • 1 Composition of human semen
  • 2 Semen and transmission of disease
  • 3 Cultural views
  • 4 See also
  • 5 References
  • 6 External links

Composition of human semen

Approximately 200- to 500-million spermatozoa (also called sperm or spermatozoans), 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 mucussecreted by the bulbourethral glandscontributes to the cohesive jelly-like texture of semen.

Seminal plasma of humanscontains a complex range of organicand inorganicconstituents. They include metal and salt ions, sugars, lipids, steroidhormones, enzymes, prostaglandinhormones, amino acidsand basic amines. The seminal plasma provides a nutritive and protective medium for the spermatozoa during their journey through the female reproductive tract. The normal environment of the vagina is a hostile one for sperm cells, for 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 environment.

Basic aminessuch as putrescine, spermine, spermidineand cadaverineare 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 DNAinside the sperm from acidic denaturation. Salts and metal ions in the semen help to create a more hospitable environment for the sperm in the vaginal canal. A typical ejaculation can contain up to 5 mgof zinc. Zinc serves to help to stabilize the DNA-containing chromatinin 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 fructoseis 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 through, and preventing their diffusion out of the semen. Prostaglandin hormones are involved in suppressing an immune response by the female against the foreign semen.

Semen and transmission of disease

The semen of a disease-free individual is harmless on the skinor if swallowed. However, semen can be the vehicle for many sexually transmitted diseases, including HIV, the virusthat causes AIDS. It is also hypothesized that componentsof semen, such as the spermatozoaas well as the seminal plasma, can cause immunosuppressionin the body when introduced to the bloodstreamor lymph. Evidence for this dates back to 1898, when Elie Metchnikoffinjected a guinea pigwith its own and foreign guinea pigsperm, finding that an antibodywas 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 lymphocytesas 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.

Cultural views

In some cultures, semen is attributed with special properties of masculinity. For instance, among the Etoropeople of Papua New Guinea, it is believed that young boys must fellatetheir elders and ingest their sperm to achieve proper sexual maturation. This act may also be attributed to the culturally active homosexuality throughout these and other tribes.

In some pagan circles, semen is viewed as a magical fluid which harnesses the power within the male. It is not uncommon in some communities for a pagan Priestess to copulate with two or more males at the same time to harvest their semen[citation needed]. It is believed that in doing so an increase in power is transferred from the males into the body of the female (Priestess). Harvesting of the ejaculate and subsequently mixing it within the body of the female is believed to greatly increase the power within the female. (Garrot-1998)

Similarly, the white tantrism (or "sex magic"), espoused by "Christian" gnostic master Samael Aun Weorin over 60 books including The Perfect Matrimony, requires that a man never spill his semen in order to activate and harness his kundalini energy.

See also

  • ejaculation
  • spermatozoon
  • spermatogenesis
  • pre-ejaculate
  • capacitation
  • sexual slangfor a list of various commonly used terms for semen.
  • Bukkake-- Japanese Semen fetish pornography.
  • cum shot

References

  • Mann T, Lutwak-Mann C. 1981. Male Reproductive Function and Semen. Berlin: Springer-Verlag. ISBN3-540-10383, 0-387-10383.
  • Shivaji S, Scheit K-H, Bhargava PM. 1990. Proteins of seminal plasma. New York: John Wiley & Sons. ISBN0-471-84685-6.

External links

  • Lipid composition of human semen
  • "What is semen made of?" by Fred Guerra at JackinWorld.com
  • "Semen Production and ejaculation" by M.J. Ecker at JackinWorld.com
  • "factors that affect spermatogenesis"
  • Can semen cure the blues?
  • Hormones in semen may help to ease female depressionaf:Semen

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This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Semen Wikipedia article Semen.

 
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