Ejaculation

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Ejaculation example Ejaculation educational seq 4.png
Ejaculation example

Ejaculation is the discharge of semen (normally containing sperm) from the male reproductory tract as a result of an orgasm. It is 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. Ejaculation is usually very pleasurable for men; dysejaculation is an ejaculation that is painful or uncomfortable. Retrograde ejaculation is the condition where semen travels backwards into the bladder rather than out the urethra.

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 masturbation or vaginal, anal, oral, or non-penetrative sexual activity may provide the necessary stimulus for a man to achieve orgasm and ejaculation. With regard to intravaginal ejaculation latency time, men typically reach orgasm 5–7 minutes after the start of penile-vaginal intercourse, taking into account their desires and those of their partners, but 10 minutes is also a common intravaginal ejaculation latency time. [1] [2] A prolonged stimulation either through foreplay (kissing, petting and direct stimulation of erogenous zones before penetration during intercourse) or stroking (during masturbation) leads to an adequate 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) can often 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.

Video of an ejaculation

When a man has achieved a sufficient level of stimulation, the orgasm and 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 and pubococcygeus muscles [5] 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. [6]

Ejaculation usually begins during the first or second contraction of orgasm. For most men, the first ejection of semen occurs during the second contraction, while the second is typically the largest expelling 40% or more of total semen discharge. After this peak, the magnitude of semen the penis emits diminishes as the contractions begin to lessen in intensity. The muscle contractions of the orgasm can continue after ejaculation with no additional semen discharge occurring. A small sample study of seven men showed an average of 7 spurts of semen followed by an average of 10 more contractions with no semen expelled. 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. [7]

Alfred Kinsey measured the distance of ejaculation, in "some hundreds" of men. In three-quarters of men tested, ejaculate "is propelled with so little force that the liquid is not carried more than a minute distance beyond the tip of the penis." In contrast to those test subjects, Kinsey noted "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 and (rarely) eight feet". [8] Masters and Johnson report ejaculation distance to be no greater than 30–60 cm (12–24 in). [9] During the series of contractions that accompany ejaculation, semen is propelled from the urethra at 500 cm/s (200 in/s), close to 18 kilometres per hour (11 mph). [5]

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. [9]

Whereas some men may have refractory periods of 15 minutes or more, some men are able to experience sexual arousal immediately after ejaculation. A short recovery period may allow partners to continue sexual play relatively uninterrupted by ejaculation. Some men may experience their penis becoming hypersensitive to stimulation after ejaculation, which can make sexual stimulation unpleasant even while they may be sexually aroused.

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". [10]

Volume

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 [11] (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. The duration of the stimulation leading up to the ejaculation can affect the volume. [12] Abnormally low semen volume is known as hypospermia and abnormally high semen volume is known as hyperspermia. 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, [13] age, stress levels, [14] and testosterone. Greater lengths of sexual stimulation immediately preceding ejaculation can result in higher concentrations of sperm. [12] 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

Diagram of the male pelvic and reproductive organs Male anatomy.png
Diagram of the male pelvic and reproductive organs

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 liquefy. 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. [15]

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 liquefies 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. [15]

Semen development during puberty
Time after first
ejaculation (months)
Average volume
(milliliter)
LiquefactionAverage sperm concentration
(million sperm/milliliter)
00.5No a 0
61.0No a 20
122.5No/Yes b 50
183.0Yes c 70
243.5Yes c 300

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

Control from the central nervous system

There is a central pattern generator in the spinal cord, made up of groups of spinal interneurons, that is involved in the rhythmic response of ejaculation. This is known as the spinal generator for ejaculation. [16]

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. [17] Expression of c-Fos in the following areas has been observed: [18] [19]

Hands-free ejaculation

Although uncommon, some men can achieve ejaculations during masturbation without any manual stimulation. Such men usually do it by tensing and flexing their abdominal and buttocks muscles along with vigorous fantasising. Others may do it by relaxing the area around the penis, which may result in harder erections especially when hyperaroused. [20]

Perineum pressing and retrograde ejaculation

Perineum pressing results in an ejaculation which is purposefully held back by pressing on either the perineum or the urethra to force the seminal fluid to remain inside. In such a scenario, the seminal fluid stays inside the body and goes to the bladder. Some people do this to avoid making a mess by keeping all the semen inside. [21] As a medical condition, it is called retrograde ejaculation. [22]

Health issues

For most men, no detrimental health effects have been determined from ejaculation itself or from frequent ejaculations,[ citation needed ] though sexual activity in general can have health or psychological consequences. A small fraction of men have a disease called postorgasmic illness syndrome (POIS), which causes severe muscle pain throughout the body and other symptoms immediately following ejaculation. The symptoms last for up to a week. [23] [24] [25] Some doctors speculate that the frequency of POIS "in the population may be greater than has been reported in the academic literature", [26] and that many POIS sufferers are undiagnosed. [27]

It is not clear whether frequent ejaculation has any effect on the risk of prostate cancer. [28] [29] [30] Two large studies examining the issue were [31] [32] [33] "Ejaculation Frequency and Subsequent Risk of Prostate Cancer" [34] and "Sexual Factors and Prostate Cancer." [35] These suggest that frequent ejaculation after puberty offers some reduction of the risk of prostate cancer. The US study involving 29,342 US men aged 46 to 81 years [34] suggested that "high ejaculation frequency was related to decreased risk of total prostate cancer". [34] An Australian study involving 1,079 men with prostate cancer and 1,259 healthy men found that "there is evidence that the more frequently men ejaculate between the ages of 20 and 50, the less likely they are to develop prostate cancer":

[T]he protective effect of ejaculation is greatest when men in their twenties ejaculated on average seven or more times a week. This group were one-third less likely to develop aggressive prostate cancer when compared with men who ejaculated less than three times a week at this age. [36]

Other animals

In mammals and birds, multiple ejaculation is commonplace. [37] [38] [ clarification needed ] During copulation, the two sides of a short-beaked echidna's penis are used sequentially. Alternating between the two sides allows for persistent stimulation to induce ejaculation without impeding the refractory period. [39]

In stallions, ejaculation is accompanied by a motion of the tail known as "tail flagging". [40] When a male wolf ejaculates, his final pelvic thrust may be slightly prolonged. [41] A male rhesus monkey usually ejaculates less than 15 seconds after sexual penetration. [42] The first report and footage of spontaneous ejaculation in an aquatic mammal was recorded in a wild Indo-Pacific bottlenose dolphin near Mikura Island, Japan in 2012. [43]

In horses, sheep, and cattle, ejaculation occurs within a few seconds, but in boars, it can last for five to thirty [44] minutes. [45] Ejaculation in boars is stimulated when the spiral-shaped penis interlocks with the female's cervix. [46] A mature boar can produce 250–300 ml (8.8–10.6 imp fl oz; 8.5–10.1 US fl oz) of semen during one ejaculation. [45] In llamas and alpacas, ejaculation occurs continuously during copulation. [47]

The semen of male dogs is ejaculated in three separate phases. [48] The last phase of a male canine’s ejaculation occurs during the copulatory tie, and contains mostly prostatic fluid. [49]

See also

Related Research Articles

Coitus interruptus, also known as withdrawal, pulling out, or the pull-out method, is a method of birth control in which a man, during sexual intercourse, withdraws his penis from a woman's vagina prior to ejaculation and then directs his ejaculate (semen) away from the vagina in an effort to avoid insemination.

Orgasm is the sudden discharge of accumulated sexual excitement during the sexual response cycle, resulting in rhythmic muscular contractions in the pelvic region characterized by sexual pleasure. Experienced by males and females, orgasms are controlled by the involuntary or autonomic nervous system. They are usually associated with involuntary actions, including muscular spasms in multiple areas of the body, a general euphoric sensation and, frequently, body movements and vocalizations. The period after orgasm is typically a relaxing experience, attributed to the release of the neurohormones oxytocin and prolactin as well as endorphins.

Urethra Tube that connects the urinary bladder to the external urethral orifice

The urethra is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra connects to the urinary meatus above the vagina, whereas in marsupials, the female's urethra empties into the urogenital sinus.

Prostate Gland of the male reproductive system in most mammals

The prostate is an accessory gland of the male reproductive system found only in some mammals. It differs between species anatomically, chemically, and physiologically. Anatomically, the prostate is found below the bladder, with the urethra passing through it. It is described in gross anatomy as consisting of lobes, and in microanatomy by zone. It is surrounded by a fibromuscular capsule and contains glandular tissue as well as connective tissue.

Skenes gland

In female human anatomy, Skene's glands or the Skene glands are glands located around the lower end of the urethra. The glands are surrounded by tissue that swells with blood during sexual arousal, and secrete a fluid from openings near the urethra, particularly during orgasm.

G-spot Anatomical detail of human female sexual organ

The G-spot, also called the Gräfenberg spot, is characterized as an erogenous area of the vagina that, when stimulated, may lead to strong sexual arousal, powerful orgasms and potential female ejaculation. It is typically reported to be located 5–8 cm (2–3 in) up the front (anterior) vaginal wall between the vaginal opening and the urethra and is a sensitive area that may be part of the female prostate.

Pre-ejaculate clear fluid emitted from the urethra of the penis during sexual arousal

Pre-ejaculate is a clear, colorless, viscous fluid that is emitted from the urethra of the penis during sexual arousal. It is similar in composition to semen but has distinct chemical differences. The presence of sperm in the fluid is variable from low to absent. Pre-ejaculate functions as a lubricant and an acid neutralizer.

Female ejaculation Expulsion of fluid during or before an orgasm

Female ejaculation is characterized as an expulsion of fluid from the Skene's gland at the lower end of the urethra during or before an orgasm. It is also known colloquially as squirting, although research indicates that female ejaculation and squirting are different phenomena, with squirting being attributed to a sudden expulsion of liquid that partly comes from the bladder and contains urine. Female ejaculation is physiologically distinct from coital incontinence, with which it is sometimes confused.

Bulbourethral gland

The bulbourethral gland or Cowper's gland is one of two small exocrine glands in the reproductive system of many male mammals. They are homologous to Bartholin's glands in females. The bulbouretheral glands are responsible for producing a pre-ejaculate fluid called Cowper's Fluid, which is secreted during sexual arousal, neutralizing the acidity of the urethra in preparation for the passage of sperm cells.

Premature ejaculation (PE) occurs when a man experiences orgasm and expels semen within a few moments of beginning sexual activity and with minimal penile stimulation. It has also been called early ejaculation, rapid ejaculation, rapid climax, premature climax and (historically) ejaculatio praecox. There is no uniform cut-off defining "premature", but a consensus of experts at the International Society for Sexual Medicine endorsed a definition of around one minute after penetration. The International Classification of Diseases (ICD-10) applies a cut-off of 15 seconds from the beginning of sexual intercourse.

Retrograde ejaculation occurs when semen which would be ejaculated via the urethra is redirected to the urinary bladder. Normally, the sphincter of the bladder contracts before ejaculation, sealing the bladder which besides inhibiting the release of urine also prevents a reflux of seminal fluids into the male bladder during ejaculation. The semen is forced to exit via the urethra, the path of least resistance. When the bladder sphincter does not function properly, retrograde ejaculation may occur. It can also be induced deliberately by a male as a primitive form of male birth control or as part of certain alternative medicine practices. The retrograde-ejaculated semen, which goes into the bladder, is excreted with the next urination.

Seminal vesicles Pair of simple tubular glands posteroinferior to the urinary bladder of male mammals

The seminal vesicles, are a pair of two coiled tubular glands that lie behind the urinary bladder of some male mammals. They secrete fluid that partly composes the semen.

Ejaculatory duct

The ejaculatory ducts are paired structures in male anatomy. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate, and open into the urethra at the seminal colliculus. During ejaculation, semen passes through the prostate gland, enters the urethra and exits the body via the urinary meatus.

Human sexual response cycle

The human sexual response cycle is a four-stage model of physiological responses to sexual stimulation, which, in order of their occurrence, are the excitement-, plateau-, orgasmic-, and resolution phases. This physiological response model was first formulated by William H. Masters and Virginia E. Johnson, in their 1966 book Human Sexual Response. Since then, other human sexual response models have been formulated.

Semen collection

Semen collection refers to the process of obtaining semen from human males or other animals with the use of various methods, for the purposes of artificial insemination, or medical study. Semen can be collected via masturbation, prostate massage, artificial vagina, penile vibratory stimulation (vibroejaculation) and electroejaculation. Semen can be collected from endangered species for cryopreservation of genetic resources.

Anejaculation is the pathological inability to ejaculate in males, with (orgasmic) or without (anorgasmic) orgasm.

In human sexuality, the refractory period is usually the recovery phase after orgasm during which it is physiologically impossible for a man to have additional orgasms. This phase begins immediately after ejaculation and lasts until the excitement phase of the human sexual response cycle begins anew with low level response. Although it is generally reported that women do not experience a refractory period and can thus experience an additional orgasm soon after the first one, some sources state that both men and women experience a refractory period because women may also experience a moment after orgasm in which further sexual stimulation does not produce excitement.

Masturbation Sexual stimulation of ones own genitals

Masturbation is the sexual stimulation of one's own genitals for sexual arousal or other sexual pleasure, usually to the point of orgasm. The stimulation may involve hands, fingers, everyday objects, sex toys such as vibrators, or combinations of these. Mutual masturbation is masturbation with a sexual partner, and may include manual stimulation of a partner's genitals, or be used as a form of non-penetrative sex.

Human penis

The human penis is an external male intromittent organ that additionally serves as the urinal duct. The main parts are the root (radix); the body (corpus); and the epithelium of the penis including the shaft skin and the foreskin (prepuce) covering the glans penis. The body of the penis is made up of three columns of tissue: two corpora cavernosa on the dorsal side and corpus spongiosum between them on the ventral side. The human male urethra passes through the prostate gland, where it is joined by the ejaculatory duct, and then through the penis. The urethra traverses the corpus spongiosum, and its opening, the meatus, lies on the tip of the glans penis. It is a passage both for urination and ejaculation of semen

Semen Organic fluid

Semen, also known as seminal fluid, is an organic fluid created to contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize the female ovum. In humans, seminal fluid contains several components besides spermatozoa: proteolytic and other enzymes as well as fructose are elements of seminal fluid which promote the survival of spermatozoa, and provide a medium through which they can move or "swim". Semen is produced and originates from the seminal vesicle, which is located in the pelvis. The process that results in the discharge of semen is called ejaculation. Semen is also a form of genetic material. In animals, semen has been collected for cryoconservation. Cryoconservation of animal genetic resources is a practice that calls for the collection of genetic material in efforts for conservation of a particular breed.

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Further reading