The sexual response cycle refers to the physical and emotional changes that occur in humans during both masturbation and intercourse. The sexual response cycle is described as a series of stages. The intensity and amount of time spent in each stage is unique to each person. Furthermore, men and women do not experience the stages in the same way. A number of sexual dysfunctions can occur over the course of the cycle. Instead of rigid stages, the cycle has a more fluid motion. Sexual Response Cycle contains four stages: excitement, plateau, orgasm, and resolution.
Phase 1: Excitement
- Initial arousal can last from a few minutes to several hours
- Muscle tension increases
- Heart rate and breath begin to accelerate
- Skin becomes flushed
- Nipples become hardened or erect
- Blood flow to genitals increase
- Vaginal lubrication begins
- The male testicles swell, scrotum tightens, and he starts secreting a lubricating liquid
Phase 2: Plateau
- Physical changes in excitement phase increase
- Breathing, heart rate, and blood pressure continue to increase
- Muscle spasms may begin in the feet, face, and hands
- Muscle tension increases
Phase 3: Orgasm
The orgasm is the climax of the sexual response cycle. It is the shortest of the phases and generally lasts only a few seconds. General characteristics of the orgasm phase include the following:
- Involuntary muscle contractions begin
- Blood pressure, heart rate, and breathing are at their highest rates, with a rapid intake of oxygen
- Muscles in the feet spasm
- There is a sudden, forceful release of sexual tension
- In women, the muscles of the vagina contract. The uterus also undergoes rhythmic contractions.
- In men, rhythmic contractions of the muscles at the base of the penis result in the ejaculation of semen.
- A rash, or “sex flush” may appear over the entire body.
Phase 4: Resolution
During resolution, the body slowly returns to its normal level of functioning. Swollen and erect body parts return to their previous size and color. This phase is marked by a general sense of well-being, enhanced intimacy and, often, fatigue. Men need recovery time after orgasm, called a refractory period, during which they cannot reach orgasm again. The duration of the refractory period varies among men and usually lengthens with advancing age. On the other hand, women have no refractory period; which makes it possible for females to have multiple orgasms.
More detailed information can be found at: http://www.webmd.com/sex-relationships/guide/sexual-health-your-guide-to-sexual-response-cycle