The Physiology of Ejaculation
The physiology of ejaculationA typical ejaculation is between one and five ml in volume, most of which comes from the seminal vesicles. There are three phases of ejaculation: emission, where the semen moves out from the seminal vesicles into the base of the penis; bladder neck closure, which should prevent ejaculate going into the bladder; and propulsion, where the semen leaves the meatus of the penis and is propelled into the vagina of the man's sexual partner. Emission is associated with the sense of one's orgasm being now inevitable (the "point of no return") and is governed by the sympathetic nervous system. The second phase of the ejaculation is bladder neck closure, during which the bladder neck is closed by the action of the sympathetic nervous system. Finally, the powerful ejaculation of semen is mediated by nerve complexes in the spine, stimulated by the sensory nerve endings of the penis responding to friction on the touch receptors of the penis, and possibly also by the distension of the urethra with the semen which has entered it during the emission phase. There are many theories as to why men come quickly (remember "quickly" refers to a man's lack of satisfaction and possibly that of his partner; it does not necessarily imply that quick ejaculation is unnatural in a biological sense). Indeed, it's intuitively obvious that rapid ejaculation is evolutionarily sensible if you might be subject to predation; therefore, contrary to popular thinking, prolonging sex and delaying ejaculation may both be learned responses. However, we do know that one of the reasons men come quickly is that they are out of touch with their bodies and the signals which it may be sending them. So, for example, the signals of impending ejaculation that would encourage a man to slow down his pelvic thrusts and so prolong intercourse may be blocked by anxiety. Unfortunately, a finding that rather confuses this issue is that men who ejaculate quickly during sex also come on average twice as quickly during masturbation, compared to men who are not classed as premature ejaculators. The implication is that anxiety is presumably non-existent or much lower during masturbation rather than sex, though of course this may not be true where men have deep-seated sexual conflicts. Masters and Johnson's definition of premature ejaculation depended to a large extent on the level of satisfaction of the woman during sex. They talked about premature ejaculation being a condition where the woman could not achieve orgasm in 50% of intercourse attempts. Well, as we know all too well, very few women ever reach orgasm through intercourse, and it's hardly the man's fault if a woman is completely unable to achieve orgasm during vaginal penetration: for most women, clitoral stimulation is very necessary for an orgasm to occur. Anxiety
and stress would seem to be important factors in premature ejaculation,
though their importance has been questioned by some researchers. For example,
when masturbating - which may not cause much anxiety - men with
premature ejaculation still come to orgasm twice as quickly as non-premature ejaculators.
And, indeed, it turns out there is no discernible difference in levels of
anxiety between the two groups of men. Also, there haven't been any studies which have identified hormonal problems in men with a tendency to rapid ejaculation. In one research study of the pituitary - testicular axis, men who experienced premature ejaculation (and this included all men, both those who showed anxiety and those who did not, those who sought out sex and those who avoided it alike), no differences of any significance were discovered in luteinizing hormone levels, total testosterone levels and free testosterone levels between men with PE and a control group. Other researchers (Fanciullaci et al.) have discussed the idea of penile hypersensitivity and a rapid bulbocavernosal reflex as possible causative factors in premature ejaculation. While it's true that other investigators have demonstrated that the lack of conscious control over ejaculation may be due to a hypersensitive and excitable glans, producing excessive neural stimulation, this hardly explains why men can learn to control their rapid ejaculation. On balance it seems more likely that the cause is pschogenic. However, Xin et al compared
somatosensory evoked nerve potentials (a measure of nerve reaction to
stimuli) in men with premature ejaculation and other men without and
discovered that the average latency was significantly
lower in both the dorsal nerve and the penile glans in men who experienced
premature ejaculation. In contrast, work by Paick
et al investigated the penile sensitivity of a group of men with a
lifelong premature ejaculation (LPE) and a group of men without and
reported there was no
statistically significant difference in the mens' response to vibratory threshold.
Nor did they find any statistically significant differences
in the sensitivity of the mens' glans, the sensitivity of their penile shafts, or
the sensitivity of their frenulums. The researchers concluded that penile
hypersensitivity, as measured by reaction to vibration, does not appear to be a
major factor in the causation of premature ejaculation. Drug treatment for premature ejaculation Effect of premature ejaculation on a man and woman's sex life Premature ejaculation - and your relationship What is an ejaculation - the physiology of ejaculation The medical view of premature ejaculation Drugs and premature ejaculation
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