Ejaculation requires exquisite coordination and timing of various muscles and glands. Thus minimal differences in timing cause disruption. Also non-neurological disturbances caused by enlarged prostate (constricting the urether and ejaculatory ducts) and constipation (generalized pressure on the lower abdominopelvic cavity) affect ejaculation.
Ejaculation is divided in two phases: emission and ejaculation proper.
Emission is under control of the sympathetic nervous system, while the ejaculatory phase is under control of a spinal reflex. Emission begins with sperm travelling along the vas deferens (spermatic cord a 30 centimeter long structure that loops over the pelvic bone ! one of these evolutionary trade-offs we carry) and entering the ejaculatory ducts and being mixed with fluids from the seminal vesicles, prostate and bulbourethral glands. The resulting fluid is called semen.
Ejaculation proper consists of approximately 5-15 rhythmic contractions of the bulbospongiosus muscle ejecting the semen through the urethra and out. Total duration of the process is about 15 seconds. (Females differ slightly as they have up to 20-30 contractions and shorter refractory period, i.e. time before next attempt can be made. Women having Skene’s glands may experience orgasm by indirect stimulation of the gland,(1) the so called G-spot. )
N.B. ejaculation is not necessarily concomitant with orgasm or vice versa.
Andra bloggar om CPPS, kroniskt bäckenbottensmärtsyndrom, ejakulation
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Wolters JP, Hellstrom WJG. Current Concepts in Ejaculatory Dysfunction. Rev Urol 8(Suppl 4):S18-S25, 2006.
(1) Gravina GL, Brandetti F, Martini P, Carosa E, Di Stasi SM, Morano S, Lenzi A, Jannini EA. Measurement of the thickness of the urethrovaginal space in women with or without vaginal orgasm. J Sex Med. 2008 5(3):610-8.
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