What happens during sexual intercourse
Sexual intercourse is a biological reproductive device. Sensual pleasure motivates humans to have sex. Certain changes occur in both genders before, during and after sexual intercourse. These include changes in the genital organs and other parts of the body.
In both males and females the sexual response cycle is divided into four phases:
- Excitement phase
- Plateau phase
- Orgasmic phase and
- Resolution phase
The main purpose of these phases of the sexual response cycle is to ensure effective intercourse leading to the fertilisation of the egg (ovum).
1. Excitement Phase
When aroused, blood is pumped into three cylinder-shaped bundles of spongy tissues in the penis. This makes the penis stiff and rigid, thereby helping it to standout of the body. The scrotal sac is raised slightly due to its muscular contraction, thereby drawing the testes upwards.
The walls of the vagina start secreting lubricating vaginal fluid. The walls also turn purple. The inner two-thirds of the vagina lengthens. The uterus (womb) rises in the pelvis. The labia majora (outer vaginal lips) open. The labia minora (inner vaginal lips) thicken. The clitoris lengthens and swells.
2. Plateau Phase:
The penis grows slightly larger. The head of the penis (glans penis) develops a reddish purple colour and becomes shiny. A few drops of sticky watery fluid (mucus) appear from the opening at the tip (meatus). The testes are drawn still higher.
The outer one-third of vagina swells as more blood flows into it. The swollen outer vagina and labia minora (inner lips) form a long elevation known as orgasmic platform. The clitoris hides behind its hood.
3. Orgasmic Phase
A series of involuntary rhythmic contractions in the testes and the penis force out semen from the penis. It is these muscular contractions that give the sexual pleasure. This process of expulsion of semen from the penis is known as ejaculation. These forceful ejaculations can squirt semen up to a distance of two feet.
The orgasmic platform contracts rhythmically 3-15 times at 0.8-second intervals. These rhythmic contractions of the orgasmic platform along with structures in the pelvis give sexual pleasure.
4. Resolution Phase
This phase is divided into two stages. In the first stage, the penis quickly shrinks to half its fully erect size. In the second stage, the penis returns to its normal flaccid size from the semi-erect or rigid stage. The second stage takes a little longer than the first stage. As the penis shrinks, the scrotum becomes loose and the testes come downward.
Ten seconds after the vaginal contractions, the clitoris returns to its normal position. The entire vagina returns to its normal colour, size and position in about 15 minutes. Uterus regains its normal position in about 20 minutes. The inner and outer lips of the vagina revert to their original colour and size.
Duration of the Phases
The excitement phase may last minutes or hours depending on the techniques used and the lack of distraction. The plateau phase is brief and intense. orgasmic phase is the shortest of all, which lasts for merely a few seconds. Many of the changes in the resolution phase are over in ten minutes.
Renewed stimulation will arouse most women just after intercourse, but most men have a refractory period immediately after sexual intercourse when re-stimulation and achieving an erection is impossible.
Changes in Other Parts of the Body
In both genders, apart from the changes in genitals, certain significant changes in other parts of the body occur. In about 75% of women and about 25% of men, reddish spots known as sex flush appear on the abdomen, throat and breasts. They disappear five minutes after the orgasm. Muscle tension occurs, causing nipple erection, tense thighs, arched back, flared nostrils etc. This tension fades within five minutes of the orgasm.
A thin film of perspiration may cover the entire body after orgasm. Heart rate, breathing rate and blood pressure go up in both genders during excitement, plateau and orgasmic phases. They return to normal soon after orgasm.