As every man is different, the sexual response of each person may differ.

HAVING sex is one way of expressing one’s feelings for another person. But deciding whether to have sex may be a difficult decision, no matter how old a person is.

The decisions one make is based on one’s religious and cultural beliefs, the values one has and the consequences of the sexual act itself. It is important to be aware of the consequences of pregnancy and sexually transmitted infections, including HIV/AIDS and to always consider them before embarking on the act itself. The choices made have to be responsible and their consequences acceptable to both parties.

There was not much scientific knowledge about sex until the pioneering work of William Masters and Virginia Johnson of the Department of Obstetrics and Gynaecology at Washington University in St Louis. They observed the sexual behaviours of 382 women and 312 men in about 10,000 complete cycles of sexual response and measured the changes in the body from 1957 to 1965. Their work was published in two classic books, Human Sexual Response (1966) and Human Sexual Inadequacy (1970).

There is a consistent pattern in the male sexual response, although it may vary somewhat between different men and in the same man, depending on the situation that he is in. A sexual response occurs in response to sexual stimulation which includes touch, smell, vision and/or thought. This leads to psychological, nervous, vascular and local genital changes.

Masters and Johnson proposed that there are four psychosexual phases in the human sexual response: excitement, plateau, orgasm and resolution. Since then, others have classified the response according to the penodynamic changes in which each of the psychosexual phases is divided into two inter-related events: excitement into latency and tumescence; plateau into erection and rigidity; orgasm into emission and ejaculation; and resolution into detumescence and refractoriness.

Another classification focuses on the functional changes during the sexual response. There is an initial phase of desire or libido which includes sex-seeking behaviour; excitement and plateau is pooled together into a single phase of erection; and orgasm is split into ejaculation, which is physical and orgasmic pleasure, which is a psychological sensation. In this classification, the normal male sexual response cycle has five inter-related events occurring sequentially: libido, erection, ejaculation, orgasm, and detumescence. Since this functional classification is the most physically quantifiable one, it will be described below.

Libido or desire

This refers to the biological need for sexual activity (sex drive or sex-seeking behaviour). Its intensity varies between individuals and within an individual over time. There is little known about its physiological basis. It is believed that sexual activity (previous and recent), psychosocial background, brain and spinal cord activation, and gonadal hormones are among the factors that regulate male sexual desire.

When there is sexual stimulation, certain physical changes happen. More blood flows into the penis and less flows out. Thus the spongy tissue in the penis fills up with blood and the penis increases in size and becomes harder. This is called an erection. How long this takes, and what it feels like differ from man to man, and even in the same man at different times.

Other physical changes may occur during this time. The testicular size increases and the scrotum are pulled closer to the trunk of the body. The skin may become flushed or red. There may be increased sensitivity of certain body parts like the nipple which may become firm or hard. There is also increase in muscle tension, blood pressure, heart rate and breathing rate.

The ejaculation phase is controlled by sympathetic nerves of the genital organs and is the result of a spinal cord reflex. This phase has two sequential processes. Initially, there is emission which is associated with the deposition of seminal fluid into the posterior urethra. There is, at the same time, contractions of the ampulla of the vas deferens, the seminal vesicles and the muscles of the prostate. The contractions occur at different speeds and in different amounts. Subsequently there is ejaculation which is the expulsion of the seminal fluid from the posterior urethra out of the body through the penile meatus.

Other physical changes during this time may include an increase in the size of the penile head which may turn purplish; secretion of fluid by Cowper’s gland, which comes out of the penile tip; an increase in the size of the testes which moves closer to the trunk and further increase in muscle tension, heart rate and blood pressure.


There are both physiological and psychological changes that contribute to orgasm, which lasts a few seconds. The physiological changes in the preceding paragraph result from stimuli transmitted through pelvic nerves. Sensory nerves in the brain perceive these events as pleasurable. The subjective sensation of orgasmic pleasure is influenced by many factors including the degree of sexual excitement, recency of sexual activity, and the psychosexual composition of the individual. Orgasm can occur without being preceded by erection and ejaculation. Conversely, contractions of pelvic muscles and ejaculation could occur in the absence of orgasmic sensations. The body changes may include a series of contractions and spasms in the legs, stomach, arms, back and the penis.

Orgasm is followed by detumescence or the resolution phase. The blood flows out of the penis within a few minutes leading to a loss of erection. The testicular size and scrotum return to normal. During this time, there is a general feeling of relaxation. As the penis has become softer, another erection or orgasm is not possible. This refractory period varies from a few minutes to much longer, depending on the individual, his age and the situation.

Advances in medicine have led to more updated views on a topic that is not as simple as it appears. The common view today is that the male sexual response is not only about physical changes but is affected by factors that include socio-cultural, political, or economic factors; partner and relationship factors; psychological factors and physiologic or medical factors. This will be discussed in another article.

A man’s sexual response is much more than physical changes. It certainly is not just blood flow and other physical changes. The physical changes in the male sexual response are influenced by several factors leading to individual differences and differences in the same man at different times and in different situations.

Source: The Star Online (Dr.Milton Lum)