1. Excitement phase
This phase has an increase in heart rate, breathing rate and blood pressure. The nipples usually get hard at this point. No pun intended. The body also prepares for sexual intercourse.
2. Plateau phase
In the second phase, the body continues to increase heart rate and circulation. Muscle tension also is noticeable. Women will find the tissues of the outer third of the vagina will swell. Men pre-ejaculate.
This is the conclusion of the plateau phase and is known for muscle contractions in the lower pelvic muscles and involuntary actions. This includes all of that screaming and moaning.
4. Resolution phase
The muscles relax, the blood pressure drops and the body calms down. The time it takes to fully relax differs from person to person. For some, it can take as long as a full 24 hours.