The copulative cycle is a set of specific physiological processes occurring in each of the partners during coitus. Social and cultural influences in sexual relationships should be taken into account, but in principle the copulative cycle during masturbation, petting, homo-or heterosexual intercourse differs only in the nature of the stimulation of the genitals.

G.S. Vasilchenko (1977) considers the copulative cycle from the standpoint of the general theory of functional systems P.K. Anokhin as a special case of such systems. In order to provide the necessary conditions for conception and attain sexual enjoyment, nature combined a number of independent systems into a single functional system: the psyche and nervous system, the endocrine apparatus, the urogenital tract and the circulatory system. All of them are directly involved in the holistic provision of the sexual sphere and make sexual intercourse possible.

The male copulative cycle consists of five consecutive stages, at each of which certain psychophysiological processes consistently occur, approximating the main biological result of sexual activity — the excretion of the male fertilizing principle. The first, mental, stage begins with an awareness of the desire for intimacy, aimed at a specific sexual object and ends with the appearance of an erection. If there are adequate conditions in the process of communicating with a potential partner, a second, erectile, stage occurs, which ends with an introitus (insertion of the penis into the vagina). The third, friction, stage is characterized by a gradual increase in arousal to a certain limit. This is followed by the fourth, ejaculatory stage, accompanied by ejaculation and orgasm, followed by a sharp decline in arousal. The fifth, refractory, stage consists in absolute and then relative sexual non-excitability during a certain period after ejaculation.

Women also have five stages of the copulative cycle. The first, mental, stage, arising against a certain erotic readiness, covers the period from a woman’s awareness of desire for sexual intimacy to making a decision about its implementation, and awareness of desire for sexual intercourse with a particular man usually occurs under the influence of erotic stimulation on his part (complements, touches, surface caress, etc.). The second, sensory, stage, following the woman’s decision to implement intimate intimacy, is characterized by the intensification of lovemaking, which acquire the character of purposeful stimulation of erogenous zones, and covers the period before introitus. This phase is characterized by increasing excitation, manifested by specific physiological reactions (lubericapia, expansion of the upper section of the vagina, etc.). The third, friction, stage covers the period from introitus to the onset of orgasm in a woman. The fourth, stage of orgasm, with individual variations inherent in different women, continues to full orgasmic discharge. The fifth, residual, stage differs from the corresponding one in men in the fact that in the overwhelming majority of cases repeated erotic stimulation leads to a new increase in sexual arousal, and the decline in arousal in women occurs smoothly and takes a longer time.

The main differences between the male and female copulative cycles are explained by the different biological orientation of the sexuality of a man and a woman. Since the main task of male sexuality is the organization of the most copulative cycle and the “delivery” of sperm to the place of fertilization of an egg, then the whole style of male sexual behavior is active, sometimes aggressive and offensive, the fulfillment of the ultimate biological task requires strong motivation before ejaculation, the bright reinforcement of which is an orgasm.

The stage of non-irritability after intercourse ensures the accumulation of mature sperm and to some extent guarantees the quality of fertilization, that is, the viability of the offspring. Female sexuality is aimed at making the selection of the most worthy of many applicants (in the interests of the same vitality of the offspring), so nature has endowed her with the potential ability for more frequent sexual contact.

The external effects of a functional system that provides male sexual reactions can be divided into five successive stages; mental, erektsionny, frictional, ejaculatory and refractory. Certain anatomical and physiological complexes, which G. S. Vasilchenko (1977) called the components of the copulative cycle, are responsible for the implementation of these stages. In men, they stand out four:

1. The neurohumoral component is associated with the activity of the deep structures of the brain and endocrine glands. It forms the energy potential of a person’s sexual desire and determines the intensity of his sexual manifestations.

2. The mental component is associated with brain activity and the mental functioning of the individual. Creates a corresponding psycho-emotional mood for sexual intercourse.

3. The erection component, the anatomical and physiological substrate of which are the centers and nerve pathways of the erection reflex, the blood supply system of the genitals and the penis itself, causes an erection with an appropriate mood.

4. The ejaculatory component is associated with the activity of the testicles, prostate, seminal vesicles, vas deferens, as well as nerve centers and nerve pathways of the ejaculatory reflex. Provides secretion of male fertilizing secretion.

During sexual contact, a man experiences an increase in sexual arousal, which is achieved due to the successive inclusion in this process of each of the four components and the summation of their effects.

In women, respectively, three components of the copulative cycle are distinguished: neurohumoral and mental, which generally correspond to the same components in men, and genitosegmental, which provides a number of purely female sexual reactions, including changes occurring in the genitals with increasing sexual arousal, and orgasmic experiences. The activity of the genital-segmental component is provided by the nerve elements (from the receptor apparatus of the genitals to the sexual centers of the brain), as well as by the female genital organs themselves. If the five stages of the copulative cycle alternate each other in the process of increasing sexual arousal, the latter is achieved by consistently contributing to the process of arousal of each of the components (four for men or three for women) and the summation of their effects.

These processes and ensure the normal course of sexual intercourse.