Ejaculation


Ejaculation
Diagram of the male pelvic and reproductive organs
The path that sperm takes from production to ejaculation

Ejaculation is the ejecting of semen (usually carrying sperm) from the male reproductory tract, and is usually accompanied by orgasm. It is usually the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. In rare cases ejaculation occurs because of prostatic disease. Ejaculation may also occur spontaneously during sleep (a nocturnal emission or "wet dream"). Anejaculation is the condition of being unable to ejaculate.

Contents

Phases

Stimulation

A usual precursor to ejaculation is the sexual arousal of the male, leading to the erection of the penis, though not every arousal nor erection leads to ejaculation. Penile sexual stimulation during vaginal, oral or anal sexual intercourse, or manual stimulation (masturbation) may provide the necessary stimulus for a man to achieve orgasm and ejaculation. Men typically reach orgasm 5–10 minutes after the start of penile-vaginal intercourse, taking into account their desires and those of their partners.[1][2] Most men could achieve orgasm sooner or delay it until later if they wished to do so.[citation needed] A prolonged stimulation either through foreplay (kissing, petting and direct stimulation of erogenous zones before penetration during intercourse) or stroking (during masturbation) leads to a good amount of arousal and production of pre-ejaculatory fluid. While the presence of sperm in pre-ejaculatory fluid is thought to be rare, sperm from an earlier ejaculation, still present in the urethra, may be picked up by pre-ejaculatory fluid.[citation needed] In addition, infectious agents (including HIV) often can be present in pre-ejaculate.

Premature ejaculation is when ejaculation occurs before the desired time. If a man is unable to ejaculate in a timely manner after prolonged sexual stimulation, in spite of his desire to do so, it is called delayed ejaculation or anorgasmia. An orgasm that is not accompanied by ejaculation is known as a dry orgasm.

Ejaculation

Video of an ejaculation.

When a man has achieved a sufficient level of stimulation, ejaculation begins. At that point, under the control of the sympathetic nervous system, semen containing sperm is produced (emission).[3] The semen is ejected through the urethra with rhythmic contractions.[4] These rhythmic contractions are part of the male orgasm. They are generated by the bulbospongiosus muscle under the control of a spinal reflex at the level of the spinal nerves S2-4 via the pudendal nerve. The typical male orgasm lasts several seconds.

After the start of orgasm, pulses of semen begin to flow from the urethra, reach a peak discharge and then diminish in flow. The typical orgasm consists of 10 to 15 contractions, although the man is unlikely to be consciously aware of that many. Once the first contraction has taken place, ejaculation will continue to completion as an involuntary process. At this stage, ejaculation cannot be stopped. The rate of contractions gradually slows during the orgasm. Initial contractions occur at an average interval of 0.6 seconds with an increasing increment of 0.1 seconds per contraction. Contractions of most men proceed at regular rhythmic intervals for the duration of the orgasm. Many men also experience additional irregular contractions at the conclusion of the orgasm.[5]

Ejaculation begins during the first or second contraction of orgasm. For most men the first spurt occurs during the second contraction. The first or second spurt is typically the largest and can contain 40 percent or more of the total ejaculate volume. After this peak the flow of each pulse diminishes. When the flow ends, the muscle contractions of the orgasm continue with no additional semen discharge. A small sample study of seven men showed an average of 7 spurts of semen (range between 5 and 10) followed by an average of 10 more contractions with no semen expelled (range between 5 and 23). This study also found a high correlation between number of spurts of semen and total ejaculate volume, i.e., larger semen volumes resulted from additional pulses of semen rather than larger individual spurts.[6]

Alfred Kinsey measured the distance of ejaculation, in "some hundred" of men. In three-quarters of men, the semen exuded from the penis, "In other males the semen may be propelled from a matter of some inches to a foot or two, or even as far as five or six (rarely eight) feet".[7] Masters and Johnson report ejaculation distance to be not greater than 30–60 cm.[8] Distance of ejaculation however, has nothing to do with sexual functioning, as during penetration of penis in vagina the distance of ejaculation plays no role. Dribbling of semen from the penis is usually sufficient for impregnation.

Refractory period

Most men experience a refractory period immediately following an orgasm, during which time they are unable to achieve another erection, and a longer period again before they are capable of achieving another ejaculation. During this time a male feels a deep and often pleasurable sense of relaxation, usually felt in the groin and thighs. The duration of the refractory period varies considerably, even for a given individual. Age affects the recovery time, with younger men typically recovering faster than older men, though not universally so.[8]

However, some men are able to achieve sufficient sexual arousal immediately after ejaculation, and others may have refractory periods of fewer than 15 minutes. A short recovery period may allow them to seamlessly continue sexual play from one ejaculation to sexual stimulation in preparation for the next. However, other men are averse to stimulation during the early part of the refractory period.

There are men who are able to achieve multiple orgasms, with or without the typical sequence of ejaculation and refractory period. Some of those men report not noticing refractory periods, or are able to maintain erection by "sustaining sexual activity with a full erection until they passed their refractory time for orgasm when they proceeded to have a second or third orgasm".[9]

Volume

Ejaculation example

The force and amount of semen that will be ejected during an ejaculation will vary widely between men and may contain between 0.1 and 10 milliliters.[10] (By way of comparison, note that a teaspoon is 5 ml and a tablespoon holds 15 ml.) Adult semen volume is affected by the time that has passed since the previous ejaculation; larger semen volumes are seen with greater durations of abstinence. It is not clear whether frequent ejaculation increases,[11] reduces[12] or has no effect[13] on the risk of prostate cancer. The duration of the stimulation leading up to the ejaculation can affect the volume.[14] Abnormally low volume is known as hypospermia. One of the possible underlying causes of low volume or complete lack of semen is ejaculatory duct obstruction. It is normal for the amount of semen to diminish with age.

Quality

The number of sperm in an ejaculation also varies widely, depending on many factors, including the time since the last ejaculation,[15] age, stress levels,[16] and testosterone. Greater lengths of sexual stimulation immediately preceding ejaculation can result in higher concentrations of sperm.[14] An unusually low sperm count, not the same as low semen volume, is known as oligospermia, and the absence of any sperm from the semen is termed azoospermia.

Development

During puberty

The first ejaculation in males often occurs about 12 months after the onset of puberty, generally through masturbation or nocturnal emission (wet dreams). This first semen volume is small. The typical ejaculation over the following three months produces less than 1 ml of semen. The semen produced during early puberty is also typically clear. After ejaculation this early semen remains jellylike and, unlike semen from mature males, fails to liquify. A summary of semen development is shown in Table 1.

Most first ejaculations (90 percent) lack sperm. Of the few early ejaculations that do contain sperm, the majority of sperm (97%) lack motion. The remaining sperm (3%) have abnormal motion.[17]

As the male proceeds through puberty, the semen develops mature characteristics with increasing quantities of normal sperm. Semen produced 12 to 14 months after the first ejaculation liquifies after a short period of time. Within 24 months of the first ejaculation, the semen volume and the quantity and characteristics of the sperm match that of adult male semen.[17]

Semen development during puberty
Time after first
ejaculation (months)
Average volume
(milliliter)
Liquefaction Average sperm concentration
(million sperm/milliliter)
0 0.5 Noa 0
6 1.0 Noa 20
12 2.5 No/Yesb 50
18 3.0 Yesc 70
24 3.5 Yesc 300

^a Ejaculate is jellylike and fails to liquify.
^b Most samples liquify. Some remain jellylike.
^c Ejaculate liquifies within an hour.

Control from the central nervous system

To map the neuronal activation of the brain during the ejaculatory response, researchers have studied the expression of c-fos, a proto-oncogene expressed in neurons in response to stimulation by hormones and neurotransmitters.[18] Expression of c-fos in the following areas has been observed:[19][20]

  • medial preoptic area (MPOA)
  • lateral septum, bed nucleus of the stria terminalis
  • paraventricular nucleus of the hypothalamus (PVN)
  • ventromedial hypothalamus, medial amygdala
  • ventral premammillary nuclei
  • ventral tegmentum
  • central tegmental field
  • mesencephalic central gray
  • peripeduncular nuclei
  • parvocellular subparafascicular nucleus (SPF) within the posterior thalamus

Health issues

For most men, no detrimental health effects have been determined from ejaculation itself or from frequent ejaculations, though sexual activity in general can have health or psychological consequences. A very small percentage of men may experience a transient Postorgasmic illness syndrome following ejaculation.[21][22]

See also

References

  1. ^ Waldinger, M.D., Quinn, P., Dilleen, M., Mundayat, R., Schweitzer, D.H., & Boolell, M. (2005). "A Multinational Population Survey of Intravaginal Ejaculation Latency Time". Journal of Sexual Medicine 2 (4): 492–497. doi:10.1111/j.1743-6109.2005.00070.x. PMID 16422843. 
  2. ^ Giuliano, F., Patrick, D., Porst, R., La Pera, G., Kokoszka, A., Merchant, S., Rothman, M., Gagnon, D., & Polverejan, E. (2008). "Premature Ejaculation: Results from a Five-Country European Observational Study". European Urology 53 (5): 1048–1057. doi:10.1016/j.eururo.2007.10.015. PMID 17950985. 
  3. ^ Bruce M. Koeppen, Bruce A. Stanton, (2008). Berne & Levy Physiology. Philadelphia, PA: Elsevier/Mosby. ISBN 978-0-323-04582-7. 
  4. ^ Walter F. Boron, Emile L. Boulpaep, (2005). Medical Physiology: A Cellular and Molecular Approach. Philadelphia, PA: Elsevier/Saunders. ISBN 1-4160-2328-3. 
  5. ^ Bolen, J. G., (1980-12-09). "The male orgasm: pelvic contractions measured by anal probe". Archives of Sexual Behavior (6): 503–21. doi:10.1007/BF01542155. PMID 7458658. 
  6. ^ Gerstenburg, T. C.; Levin, RJ; Wagner, G (1990). "Erection and ejaculation in man. Assessment of the electromyographic activity of the bulbocavernosus and ischiocavernosus muscles". British Journal of Urology 65 (4): 395–402. doi:10.1111/j.1464-410X.1990.tb14764.x. PMID 2340374. 
  7. ^ Kinsey, A. C., Pomeroy, W. B., Martin, C. E. & Gebhard, P. H. (1998). Sexual Behavior in the Human Female. Indiana University Press. pp. 634. ISBN 978-0253334114. http://books.google.com/?id=9GpBB61LV14C&lpg=PA530&dq=sexual%20behavior%20of%20human%20female&pg=PA634#v=onepage&q=. 
  8. ^ a b Masters, W.H., & Johnson, V.E. (1970). Human Sexual Response. Boston: Little, Brown and Company. 
  9. ^ Dunn, M.E., & Trost, J.E. (1989). "Male Multiple Orgasms: A Descriptive Study". Archives of Sexual Behavior 18 (5): 377–387. doi:10.1007/BF01541970. PMID 2818169. 
  10. ^ Rehan N, Sobrero AJ, Fertig JW. (1975). "The semen of fertile men: statistical analysis of 1300 men". Fertility and Sterility 26 (6): 492–502. PMID 1169171. 
  11. ^ Dimitropoulou, Polyxeni; Artitaya Lophatananon, Douglas Easton, Richard Pocock, David P. Dearnaley, Michelle Guy, Steven Edwards, Lynne O'Brien, Amanda Hall, Rosemary Wilkinson, Rosalind Eeles, Kenneth R. Muir (November 11, 2008). "Sexual activity and prostate cancer risk in men diagnosed at a younger age". BJU International 103 (2): 178–185. doi:10.1111/j.1464-410X.2008.08030.x. OCLC 10.1111/j.1464-410X.2008.08030.x. PMID 19016689. 
  12. ^ "Masturbation Cuts Cancer Risk". BBC News Online. 2003-07-16. http://news.bbc.co.uk/2/hi/health/3072021.stm. Retrieved 2009-03-04. , Giles GG, Severi G, English DR, Hopper JL. (2004). "Frequency of ejaculation and risk of prostate cancer". JAMA 292 (3): 329. doi:10.1001/jama.292.3.329-a. PMID 15265846. 
  13. ^ Leitzmann MF, Platz EA, Stampfer MJ, Willett WC, Giovannucci E. (2004). "Ejaculation frequency and subsequent risk of prostate cancer". JAMA 291 (13): 1578–86. doi:10.1001/jama.291.13.1578. PMID 15069045. 
  14. ^ a b Pound N, Javed MH, Ruberto C, Shaikh MA, Del Valle AP. (2002). "Duration of sexual arousal predicts semen parameters for masturbatory ejaculates". Physiol Behav 76 (4–5): 685–9. doi:10.1016/S0031-9384(02)00803-X. PMID 12127009. 
  15. ^ "Semen and sperm quality". Dr John Dean, netdoctor.co.uk. http://www.netdoctor.co.uk/menshealth/facts/semenandsperm.htm. Retrieved 2009-03-04. 
  16. ^ "Biological Basis of Heredity: Cell Reproduction". Dr. Dennis O'Neil, Behavioral Sciences Department, Palomar College, San Marcos, California. http://anthro.palomar.edu/biobasis/bio_2.htm. Retrieved 2009-03-04. 
  17. ^ a b Janczewski, Z. and Bablok, L. (1985). "Semen Characteristics in Pubertal Boys". Archives of Andrology 15 (2–3): 199–205. doi:10.3109/01485018508986912. PMID 3833078. 
  18. ^ Sagar SM, "et al." (1988). "Expression of c-fos protein in brain: metabolic mapping at the cellular level". Science 240 (4857): 1328–1332. doi:10.1126/science.3131879. PMID 3131879. 
  19. ^ Pfaus JG and Heeb MM, (1997). "Implications of immediate-early gene induction in the brain following sexual stimulation of female and male rodents". Brain Res Bull 44: 397–407. doi:10.1016/S0361-9230(97)00219-0. PMID 9370204. 
  20. ^ Veening JG and Coolen LM, (1998). "Neural activation following sexual behavior in the male and female rat brain". Behav Brain Res 92: 181–193. doi:10.1016/S0166-4328(97)00190-3. PMID 9638960. 
  21. ^ Dexter S (2010). "Benign coital headache relieved by partner's pregnancies with implications for future treatment". British Medical Journal. http://casereports.bmj.com/content/2010/bcr.10.2009.2359.short?rss=1. 
  22. ^ Richard Balon, R. Taylor Segraves (2005). Handbook of sexual dysfunction. Informa Health Care. ISBN 9780824758264. http://books.google.com/?id=oVbn7A3BtEUC&pg=PA241&dq=Postorgasmic+Illness+Syndrome. Retrieved 2009-05-11. 

Further reading


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  • ÉJACULATION — Émission en jet saccadé d’un à trois millilitres de sperme au paroxysme de l’orgasme masculin. Produite par la contraction des vésicules séminales et de l’ampoule du canal déférent, rythmée par les contractions spasmodiques des muscles qui… …   Encyclopédie Universelle

  • Ejaculation — Éjaculation L éjaculation est l expulsion (habituellement en jet) d un liquide biologique, à l approche ou au moment de l orgasme. Chez l homme, l éjaculat est constitué de sperme, alors que chez la femme, il s agit du fluide sécrété par les… …   Wikipédia en Français

  • Ejaculation — E*jac u*la tion, n. [Cf. F. [ e]jaculation.] 1. The act of throwing or darting out with a sudden force and rapid flight. [Archaic or Technical] An ejaculation or irradiation of the eye. Bacon. [1913 Webster] 2. The uttering of a short, sudden… …   The Collaborative International Dictionary of English

  • éjaculation — ÉJACULATION. s. fém. Terme de Physique. Émission de la semence avec une certaine force.Éjaculation, se dit aussi d Une prière fervente, et qui part du coeur …   Dictionnaire de l'Académie Française 1798

  • ejaculation — c.1600, of fluids; 1620s, of utterances, from Fr. éjaculation, from éjaculer, from L. ejaculari (see EJACULATE (Cf. ejaculate)) …   Etymology dictionary

  • Ejaculation — Ejaculation, lat. deutsch, Auswerfung, Ausspritzung; Ejaculator, der bei der Ausspritzung des Sperma thätige Muskel; ejaculiren, ausspritzen …   Herders Conversations-Lexikon

  • ejaculation — index outburst Burton s Legal Thesaurus. William C. Burton. 2006 …   Law dictionary

  • ejaculation — [ē jak΄yo͞o lā′shən, ijak΄yo͞o lā′shən; ē jak΄yəlā′shən; i jak′yəlā′shən] n. [see EJACULATE] 1. a sudden ejection of fluid, esp. of semen, from the body 2. a sudden vehement utterance; exclamation 3. R.C.Ch. any very brief private prayer …   English World dictionary

  • Éjaculation — L’éjaculation est l’expulsion (habituellement en jet) d’un liquide biologique, à l’approche ou au moment de l’orgasme lors d’un rapport sexuel, d’une masturbation ou d’une pollution nocturne. Chez l’homme, l’éjaculat est constitué de sperme ou de …   Wikipédia en Français

  • ejaculation — /i jak yeuh lay sheuhn/, n. 1. an abrupt, exclamatory utterance. 2. the act or process of ejaculating, esp. the discharge of semen by the male reproductive organs. [1595 1605; EJACULATE + ION] * * * ▪ physiology  the release of sperm cells and… …   Universalium


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