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sheep shagers
{{pp-move-indef}}{{twootheruses|male ejaculation|female ejaculation|Female ejaculation|the grammatical term|Ejaculation (grammar)}}
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'''Ejaculation''' is the ejecting of ] from a ], and is usually accompanied by ]. It is usually the final stage and natural objective of ], and an essential component of natural ]. In rare cases ejaculation occurs because of ]. Ejaculation may also occur spontaneously during ] (a ] or "wet dream"). ''']''' is the condition of being unable to ejaculate.

==Phases==
===Stimulation===
{{See also|Sexual stimulation}}
A usual precursor to ejaculation is the ] of the male, leading to the ] of the ], though not every arousal nor erection leads to ejaculation. Penile ] during vaginal, oral or anal ], or ] (masturbation) may provide the necessary stimulus for a man to achieve ] 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.<ref>{{cite journal|author=Waldinger, M.D., Quinn, P., Dilleen, M., Mundayat, R., Schweitzer, D.H., & Boolell, M.|year=2005|title=A Multinational Population Survey of Intravaginal Ejaculation Latency Time|journal=Journal of Sexual Medicine|volume=2|pages=492–497|doi=10.1111/j.1743-6109.2005.00070.x|pmid=16422843|issue=4}}</ref><ref>{{cite journal|author= Giuliano, F., Patrick, D., Porst, R., La Pera, G., Kokoszka, A., Merchant, S., Rothman, M., Gagnon, D., & Polverejan, E.|year=2008|title=Premature Ejaculation: Results from a Five-Country European Observational Study|journal=European Urology|volume=53|issue=5|pages=1048–1057|doi= 10.1016/j.eururo.2007.10.015|pmid= 17950985}}</ref> Most men could achieve orgasm sooner or delay it until later if they wished to do so. 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 does not contain sperm. If ejaculation occurs prior to "pre-ejaculating" then it can pick up sperm that did not leave the urethra, and cause a possible pregnancy, but is not probable.<ref>http://www.ncbi.nlm.nih.gov/pubmed/12286905?ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum </ref>

] is the phrase used 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 ] or ]. An orgasm that is not accompanied by ejaculation is known as a ].

===Ejaculation===
]
When a man has achieved a sufficient level of stimulation, ejaculation begins. At that point, under the control of the ], ] containing ] is produced. The semen is ejected through the ] with rhythmic contractions.<ref>{{cite book | author = Walter F. Boron, Emile L. Boulpaep, | title = Medical Physiology: A Cellular and Molecular Approach | publisher = Elsevier/Saunders | location = Philadelphia, PA | year = 2005 | isbn = 1-4160-2328-3}}</ref> These rhythmic contractions are part of the male orgasm. They are generated by the ] under the control of a ] at the level of the ]s S2-4 via the ]. 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.<ref>{{cite journal | author=Bolen, J. G., |pmid=7458658| title=The male orgasm: pelvic contractions measured by anal probe | journal= Archives of Sexual Behavior| date= 1980-12-09| issue=6 | pages=503–21 | doi = 10.1007/BF01542155}}</ref>

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.<ref name="Gerstenburg">{{cite journal| author=Gerstenburg, T. C. | pmid=2340374 | title= Erection and ejaculation in man. Assessment of the electromyographic activity of the bulbocavernosus and ischiocavernosus muscles | journal= British Journal of Urology | year= 1990 | volume=65| issue=4| pages=395–402| doi=10.1111/j.1464-410X.1990.tb14764.x| first2=RJ| first3=G}}</ref> Men who volunteer for such studies might be proud of their orgasms and therefore have disproportionately more robust orgasms than the average.

] measured the distance of ejaculation, in "some hundred" of men. In three-quarters of men, the ] exuded of the penis, "In other males the semen may be propelled from a matter of some inches to foot or two, or even as far as five or six (rarely eight) feet".<ref>{{Cite book | author=Kinsey, A. C., Pomeroy, W. B., Martin, C. E. & Gebhard, P. H.| title=Sexual Behavior in the Human Female|year=1998|publisher=Indiana University Press|isbn=978-0253334114|pages=634|url=http://books.google.com/books?id=9GpBB61LV14C&lpg=PA530&dq=sexual%20behavior%20of%20human%20female&hl=pl&pg=PA634#v=onepage&q=&f=false}}</ref> ] report ejaculation distance to be not greater than 30–60&nbsp;cm.<ref name=M&J>{{cite book|author=Masters, W.H., & Johnson, V.E.|title=Human Sexual Response|year=1970|publisher=Little, Brown and Company|location=Boston}}</ref>. 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 ] 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. 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.<ref name=M&J/>

However, some men are able to achieve sufficient sexual arousal immediately after ejaculation, and others may have refractory periods of less 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".<ref>{{cite journal|author=Dunn, M.E., & Trost, J.E.|year=1989|title=Male Multiple Orgasms: A Descriptive Study|journal=Archives of Sexual Behavior|volume=18|pages=377–387|doi=10.1007/BF01541970|pmid=2818169|issue=5}}</ref>

===Volume===
The ] and amount of ] that will be ejected during an ejaculation will vary widely between men and may contain between 0.1 and 10 ]s.<ref>{{cite journal | journal=Fertility and Sterility | volume=26 | issue=6 | pages=492–502 | date=1975 | author=Rehan N, Sobrero AJ, Fertig JW. | title=The semen of fertile men: statistical analysis of 1300 men | pmid=1169171 }}</ref> (By way of comparison, note that a ] 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<ref>{{cite journal|last=Dimitropoulou|first=Polyxeni|coauthors= 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|date=November 11 2008 |title=Sexual activity and prostate cancer risk in men diagnosed at a younger age|journal=BJU International|volume=103|issue=2|pages=178–185|oclc=10.1111/j.1464-410X.2008.08030.x|url=|doi=10.1111/j.1464-410X.2008.08030.x|pmid=19016689}}</ref>, reduces<ref>{{cite news| url=http://news.bbc.co.uk/2/hi/health/3072021.stm |title=Masturbation Cuts Cancer Risk | publisher= BBC News Online |date=2003-07-16 |accessdate=2009-03-04}}, {{cite journal | journal=JAMA | volume=292 | issue=3 | pages=329 | date=2004 | author=Giles GG, Severi G, English DR, Hopper JL. | title=Frequency of ejaculation and risk of prostate cancer | pmid=15265846 | doi = 10.1001/jama.292.3.329-a }}</ref> or has no effect<ref>{{cite journal | journal=JAMA | volume=291 | issue=13 | pages=1578–86 | date=2004 | author=Leitzmann MF, Platz EA, Stampfer MJ, Willett WC, Giovannucci E. | title=Ejaculation frequency and subsequent risk of prostate cancer | pmid=15069045 | doi = 10.1001/jama.291.13.1578 }}</ref> on the risk of prostate cancer. The duration of the stimulation leading up to the ejaculation can affect the volume.<ref>{{cite journal | journal=Physiol Behav | volume=76 | issue=4-5 | pages=685–9 | date=2002 | author=Pound N, Javed MH, Ruberto C, Shaikh MA, Del Valle AP. | title=Duration of sexual arousal predicts semen parameters for masturbatory ejaculates | pmid=12127009 | doi = 10.1016/S0031-9384(02)00803-X }}</ref> Abnormally low volume is known as ], though it is normal for the amount of semen to diminish with age.

===Quality===
{{Main|Semen quality}}
The number of ] in an ejaculation also varies widely, depending on many factors, including the time since the last ejaculation,<ref>{{cite web | url=http://www.netdoctor.co.uk/menshealth/facts/semenandsperm.htm | title=Semen and sperm quality | publisher=Dr John Dean, netdoctor.co.uk | accessdate=2009-03-04}}</ref> age, stress levels,<ref>{{cite web | url=http://anthro.palomar.edu/biobasis/bio_2.htm | title= Biological Basis of Heredity: Cell Reproduction | publisher=Dr. Dennis O'Neil, Behavioral Sciences Department, Palomar College, San Marcos, California | accessdate=2009-03-04}}</ref> and ]. An unusually low sperm count, not the same as low semen volume, is known as ], and the absence of any sperm from the semen is termed ].

==Development==
===During puberty===
The first ejaculation in males often occurs about 12 months after the onset of ], generally through ] or ] (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 ]. 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.<ref name=Janczewski>{{cite journal | author = Janczewski, Z. and Bablok, L. | year=1985| title=Semen Characteristics in Pubertal Boys| journal= Archives of Andrology | volume=15 | pages= 199–205 | pmid= 3833078| doi=10.3109/01485018508986912 | issue = 2-3}}</ref>

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.<ref name=Janczewski />

{| class="wikitable" border="1"
|-
|+ Table 1 - Semen Development During Puberty
! Time after first <br>ejaculation (months)
! Average volume <br>(milliliter)
! Liquefaction
! Average sperm concentration <br>(million sperm/milliliter)
|-
| 0
| 0.5
| No (1)
| 0
|-
| 6
| 1.0
| No (1)
| 20
|-
| 12
| 2.5
| No/Yes (2)
| 50
|-
| 18
| 3.0
| Yes (3)
| 70
|-
| 24
| 3.5
| Yes (3)
| 300
|}
<br/>Note 1 - Ejaculate is jellylike and fails to liquify.<br/>Note 2 - Most samples liquify. Some remain jellylike.<br/>Note 3 - 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.<ref>{{cite journal | author=Sagar SM, "et al." | pmid= 3131879| title=Expression of c-fos protein in brain: metabolic mapping at the cellular level | journal= Science | pages=1328–1332 | doi = 10.1126/science.3131879| year=1988| volume=240 | issue=4857}}</ref> Expression of c-fos in the following areas has been observed:<ref>{{cite journal | author= Pfaus JG and Heeb MM, | pmid=9370204| title= Implications of immediate-early gene induction in the brain following sexual stimulation of female and male rodents | journal=Brain Res Bull| year= 1997 | volume=44| pages=397–407 | doi = 10.1016/S0361-9230(97)00219-0 }}</ref><ref>{{cite journal | author=Veening JG and Coolen LM, | pmid=9638960 | title=Neural activation following sexual behavior in the male and female rat brain | journal= Behav Brain Res | year= 1998 | volume= 92 | pages=181–193 | doi = 10.1016/S0166-4328(97)00190-3 }}</ref>
* 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==
{{Unreferenced section|date=August 2009}}
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 ] following ejaculation.

In one study, more frequent ejaculation earlier in one's life predicted lower rates of prostate cancer later on. Researchers have proposed that ejaculation may "flush out" carcinogens that accumulate in the prostate. However, no definitive reason for the link has been found, nor has it been proven that ejaculation is the direct cause of the reduced risk (but because the ejaculation occurred many years before cancer developed, it is not just that cancer causes reduced ejaculation).

==See also==
{{Commons category|Ejaculation}}
* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ]
* ] - ejaculation in Jewish law
* ]
* ]
* ]
* ]
* ]

==References==
{{reflist}}

==Further reading==
*{{cite web | url=http://www.focusonfertility.org/resource_swimming_conception.htm | archiveurl=http://web.archive.org/web/20080112144449/http://www.focusonfertility.org/resource_swimming_conception.htm | archivedate=2008-01-12 | title=Swimming Toward Conception: The Semen Analysis | publisher=Focus on Fertility, American Infertility Association and Organon Pharmaceuticals USA Inc}}

{{Reproductive physiology}}
{{sex}}

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Revision as of 19:34, 2 February 2010

sheep shagers