In the plateau phase, variables such as respiratory rate, heart rate, and blood pressure are sustained at a high level, or rise slightly, for a few seconds to a few minutes before orgasm. In emission, the sympathetic nervous system causes peristaltic contractions of the ductus deferens, which propels sperm from the tail of the epididymus and into the ampulla of the ductus deferens. Further contractions propel the sperm into the prostatic urethra along with prostatic fluid and secretions from the seminal vesicles. Semen in the urethra activates reflexes that produce expulsion of the semen. The bulbospongiosus, which envelopes the root of the corpus spongiosum, undergoes five or six strong, spasmodic contractions that compress the urethra and forcibly expel the semen.
Resolution Immediately following orgasm comes the resolution phase.
Discharge of the sympathetic nervous system reduces blood flow to the penis, and gradually the penis undergoes detumescence. In men, resolution is followed by a refractory period, lasting anywhere from 10 minutes to a few hours, in which it is usually impossible to attain another erection and orgasm.