Anatomy and physiology of the male reproductive system

The human body is a complex system, which even simple copying to modern engineers is not yet possible (except that in the cinema - various cyborgs, more or less similar to people). And a separate talk deserves the genitourinary system of a man.

What is remarkable about this system? Basically the fact that a small and mild, quiet penis of a man becomes hard when excited, and increases almost twofold, while there are no bones (unlike some animals). This increase is called an erection.

To the inner genitalia of a man are testicles with appendages, vas deferens, seminal vesicles, prostate and bulbo-urethral glands, to the external - penis and scrotum. The length of the penis varies from 5 to 15 cm in a state of "rest" and up to 15 or more cm in a state of erection. The penis is formed mainly by blood vessels surrounded and supported by a connective tissue and covered with skin. Inside there are three extensible tissue porous longitudinal strands surrounded by connective tissue (two cavernous bodies and a spongy body), which, filled with arterial blood, increase and provide an erection. The urethra passes through the central part of the spongy body. The spongy body ends with the head of the penis, surrounded by a movable skin fold - the foreskin.

With sexual arousal, the most sensitive areas are the head, the bridle (the lower part of the prepuce) and the skin, which contains many nerve endings.

To ensure that the process of erection is without disturbances, several conditions must be met. First, it is necessary for the brain and spinal cord to function normally, responsible for the appearance of a signal about the need for an erection. In other words, it is necessary for a man to be capable of sexual arousal. Secondly, there should be no obstacles in the way of the transfer of this impulse (the integrity of the pathways-nerves). Thirdly, the cardiovascular system, which ensures blood filling of the cavernous bodies, should function normally.

Men have two testicles, one of which is larger than the other. Sperm is produced in the seminiferous tubules, and in the interstitial cells of Leydig, a testosterone hormone is produced. From the period of puberty, sex cells-spermatocytes begin to form, they are formed throughout life. From the cells in the walls of the seminiferous tubules, hundreds of millions of spermatozoa are formed during the maturation cycle. The process of their maturation lasts 2-3 months. Sertolia cells in the tissue of the seminiferous tubules secrete some liquid. Ripening spermatozoa move along the tubules to the epididymis (a long wriggling tube) along which they pass for a period of 2 to 4 weeks. In the tail (end), the epididymis is stored until ejaculation (ejaculation), then either expires into the urine, or dies.

Sperm formation is promoted by follicle-stimulating hormone and testosterone (it forms and supports secondary masculine signs and stimulates growth).

In the male reproductive tract the following major glands function:

• prostate;
• seminal vesicles;
• bulbo-urethral (Cooper's) glands.

The prostate glands entirely with its capsule, consisting of smooth muscle fibers, the urethra. Its increase, especially in chronic inflammatory processes and benign tumors (adenomas) in the elderly, can significantly impede urination and make it extremely painful, etc.

Thus, the seminal fluid (sperm) is a mixture of excreta:

• 60-70% of it is the allocation of seminal vesicles (sticky, yellowish mass);
• about 20% - the secretion of the prostate gland.

With ejaculation, about 3-4 ml of sperm are released, in which about 2% is true sperm containing about 300 million spermatozoa (100 million / ml). If their number decreases to 20-40 million / ml, the chances of successful fertilization of the female egg are scanty.

It should be clarified that under the influence of sexual arousal, when the peak of sexual tension is reached simultaneously (in the norm), an unusually sweet stage occurs-orgasm:

• contraction of the smooth muscles of the vas deferens, the seminal vesicles and the prostate gland leads to the ejection of secrets into the urethra (the stage of emission);
• seminal fluid erupts from the urethra due to contractions of the striated muscles located at the base of the penis (ejaculation stage).

Simultaneously, the internal sphincter of the bladder closes with the relaxation of the external sphincter.

[1], [2], [3], [4]