How the male reproductive system works

The male reproductive system results from a set of internal and external organs, which release hormones, androgens, and are regulated by the brain through the hypothalamus, which secrete the gonadotropin-releasing hormone and the pituitary, which releases the follicle-stimulating and luteinizing hormone .

The primary sexual characteristics, which include the male genitals, are formed during fetal development and the secondary ones are formed from puberty, between the ages of 9 and 14, when the boy’s body becomes a body male, in which the male genital organs develop, as well as the appearance of the beard, hair throughout the body and thickening of the voice.

What are the male sexual organs

1. Scrotum

The scrotum is a bag of loose skin, which has the function of supporting the testicles. They are separated by a septum, which is formed by muscle tissue and when it contracts, it causes the skin of the scrotum to wrinkle, which is very important for regulating the temperature, since it is in the testicles that sperm are produced. 

The scrotum is able to keep the temperature of the testicles below body temperature, as it is outside the pelvic cavity. In addition, in some conditions, such as exposure to cold, the cremaster muscle, which inserts into the scrotum and suspends the testicle, raises the testicles during exposure to the cold, preventing it from cooling, which also occurs during sexual arousal. 

2. Testicles

Men normally have two testicles, which are organs with an oval shape and which are about 5 cm long and 2.5 cm in diameter each, weighing about 10 to 15 grams. These organs have the function of secreting the sex hormones involved in spermatogenesis, which consists of the formation of sperm, and which stimulate the development of male sexual characteristics.

The functioning of the testicles is influenced by the central nervous system, through the hypothalamus, which secretes the gonadotropin-releasing hormone (GnRH), and the pituitary, which releases the follicle-stimulating (FSH) and luteinizing hormones (LH).

Inside the testicles, there are seminiferous tubules, where the differentiation of germ cells into sperm occurs, being then released into the lumen of the tubules and continuing to mature along their path through the ducts of the reproductive system. In addition, seminiferous tubules also have Sertoli cells, which are responsible for the nutrition and maturation of germ cells, and the interstitial tissue that surrounds these tubules contains Leydig cells, which produce testosterone.

3. Accessory sexual glands

These glands are responsible for secreting a large part of the semen, which is very important for the transport and nutrition of sperm and for the lubrication of the penis: 

  • Seminal vesicles: these  are structures that are behind the base of the bladder and in front of the rectum and produce an important fluid to adjust the pH of the urethra in men and to reduce the acidity of the female genital system, so that it becomes compatible with the life of sperm. . In addition, it has fructose in its composition, which is important to produce energy for their survival and locomotion, so that they can fertilize the egg;
  • Prostate:  this structure is located below the bladder, surrounds the entire urethra and secretes a milky liquid that contributes to its clotting after ejaculation. In addition, it also contains substances that are used for energy production, which contribute to the movement and survival of sperm.
  • Bulbourethral glands or Cowper’s glands:  these glands are located below the prostate and have ducts that open in the spongy part of the urethra, where they secrete a substance that decreases the acidity of the urethra caused by the passage of urine. This substance is released during sexual arousal, which also has a lubricating function, facilitating sexual intercourse.

4. Penis

The penis is a cylindrical structure, composed of cavernous bodies and spongy bodies, which are located around the urethra. At the distal end of the penis is the glans, covered by the foreskin, which has the function of protecting this region.

In addition to facilitating the exit of urine, the penis also has an important function in sexual intercourse, whose stimuli cause the dilation of its arteries that irrigate the cavernous and spongy bodies and cause an increase in the amount of blood in that region, also leading to an increase and hardening of the penis, facilitating its penetration into the vaginal canal during sex.

How Hormone Control Works

Male reproduction is controlled by hormones that stimulate the development of the reproductive organs, the production of sperm, the development of secondary sexual characteristics and also sexual behavior.

The functioning of the testicles is controlled by the hypothalamus, which releases gonadotropin-releasing hormone (GnRH), stimulating the pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones act directly on the testis, controlling spermatogenesis and the production of androgen, estrogen and progesterone hormones. 

Among the latter, the most abundant hormones in men are androgens, with testosterone being the most important and the one related to the development and maintenance of male sexual characteristics, also influencing the formation of sperm.

Androgens also have an influence on the development of primary and secondary sexual characteristics. Primary sexual characteristics, such as male external and internal sexual organs, are formed during embryo development and secondary sexual characteristics are developed from puberty.

Puberty occurs around the age of 9 to 14, giving rise to changes in body shape, growth of beard and pubic hair and the rest of the body, thickening of the vocal cords and the emergence of sexual desire. In addition, there is also the growth of the penis, scrotum, seminal vesicles and prostate, increased sebaceous secretions, responsible for acne. 

See also how the female reproductive system works.

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