Oxytocin plays a role in sexual arousal and orgasm in both men and women. You probably know the effects of adrenaline on the heart and body from exhilarating or frightening situations. Adrenaline is also involved in sex and orgasm. The central nervous system signals to the heart, which starts to beat faster. Adrenaline is released and dilates arteries which increases blood flow to the muscles involved in sex.
Breathing becomes shallower and quicker as the lungs work to oxygenate the blood.
The body's cooling system kicks in, and you start to sweat. The sudden release of accumulated sexual tension results in rhythmic muscular contractions in the pelvic region. I first feel my toes and head tingle, then two waves in my body swell, race towards each other than crash. That is orgasm. For men , muscular contractions force the ejaculate into a little depository at the base of the penis called the urethral bulb .