Overview
Hormones in the male human body function as coordinators for many bodily processes, including the regulation of organ and cell function. Men primarily produce three types of hormones: follicle-stimulating hormones, luteinizing hormones and steroid hormones. These chemicals control everything from hair growth to sperm production to muscle development, and decrease in production as men age. Hormone replacement therapy for men has been developed and is available from qualified physicians.
Follicle-Stimulating Hormones
Follicle-stimulating hormones (FSH) stimulate the gonads and have a direct impact on supporting the maturation of sperm. These hormones are not required to maintain life, but they are necessary for reproduction. FSH are gonadotropic hormones, which are associated with the endocrine system. A number of hormones inhibit and activate FSH production in a complex cycle.
Decreased production of FSH can result in fertility problems due to low sperm counts in men. Excess FSH has no biological effect, but can be the result of gonad failure or pituitary tumors.
Decreased production of FSH can result in fertility problems due to low sperm counts in men. Excess FSH has no biological effect, but can be the result of gonad failure or pituitary tumors.
Luteinizing Hormones
Luteinizing hormones (LH) stimulate the gonads to secrete sex steroids and are also known in men as interstitial cell stimulating hormone (ICSH). LH is created in the pituitary cells, the same ones that synthesize FSH. The National Cancer Institute website describes the role of LH as "to make testosterone." As with FSH, decreased production of LH can result in fertility problems due to low sperm counts in men.
Steroids
According to Hudson's Guide, steroid hormones are synthesized mostly in the gonads and more minutely in the adrenal glands. Steroid hormones come in five varieties: androgens, estrogens, progestins, glucocorticoids and mineralocorticoids.
The hormones commonly considered to be "sex hormones" in the body are testosterone, estrogen, and progesterone. Testosterone is often referred to as a "male" hormone, and estrogen and progesterone are often referred to as "female" hormones. However, it is interesting to note that no exclusively "male" or "female" hormones have been identified. All hormones characterized to date are present in all people regardless of sex, as are the receptor mechanisms that respond to those hormones.
In fact, the physical observation of the sexes we call "male" and "female" in nature is the result of differences in the amounts of individual hormones in the body and differences in their patterns of secretion (first in utero and then again during puberty) rather than their presence or absence. In other words, testosterone, estrogen, and progesterone are produced by men and women, but in differing amounts and in different patterns.
Glucocorticoids impact physiological systems, the best known of which are carbohydrate metabolism and immune function. These hormones are critical for fetal development, affecting lung maturation.
Mineralocorticoids regulate concentrations of minerals, particularly sodium and potassium, in extracellular fluids. A lack of mineralocorticoids is lethal as a result of electrolyte imbalances and the low blood pressure and cardiac failure that follow.
Other Male Hormones
Dehydroepiandrosterone (DHEA) is an endogenous (naturally occurring in the human body) steroid hormone that is needed to produce other types of hormones including estrogen and testosterone. It is produced in the adrenal cortex from cholesterol and is commonly called dehydroandrosterone.
Androstenedione is the common precursor of male and female sex hormones. It is an androgenic steroid produced by the testes, adrenal cortex and ovaries.
Androstenedione have been shown to increase serum testosterone levels, which helps maintain balance the mental faculties of men.
Androstenediol has been shown to increase androgen prohormone, testosterone, and estradiol. It functions to stimulate the immune system.
Androsterone is a chemical by-product created during the breakdown of androgens. It can also be derived from progesterones. Androsterones have also minor masculinising effects on the body but not with the same intensity of testosterone.
Dihydrotestosterone (DHT) is a metabolite of testosterone that binds strongly with androgen receptors. It is responsible for the formation of male sex-specific characteristics such as the male genitalia and prostate.
Primary and Secondary Sex Characteristics
Androgens, estrogens, and progestins are the hormones mainly responsible for the development "secondary sex characteristics".
"Primary sex characteristics" refer to physical characteristics present in the human body that are directly involved in reproductive function: namely the gonads and their accessory structures. The development of primary sex characteristics happens to the fetus in the womb.
"Secondary sex characteristics" refer to physical characteristics that are typically associated with "males"/"men" and "females"/"women" but are not necessarily related to reproductive function. Examples would include facial hair growth and deepening of the voice in men, and growth of breasts and increased fat deposits around the hips in women. The development of secondary sex characteristics usually begins at puberty, as the levels and patterns of secretion of the sex hormones in the body begin to change at that time.
The androgen testosterone (and its derivative dihydrotestosterone [DHT]) is responsible for producing masculine secondary sex characteristics such as facial hair growth, deepening of the voice, increased body hair growth, and increased muscle development.
Estrogen and progesterone play a vital role in the menstrual cycle in females. Estrogen is also mainly responsible for producing feminine secondary sex characteristics such as breast development and increased body fat deposits around the hip and thigh areas.
Testosterone, estrogen, and progesterone are produced mainly in the "gonads" (the testes and the ovaries). Two other important hormones-- "luteinizing hormone" (LH) and "follicle-stimulating hormone" (FSH)-- stimulate the gonads into secreting sex hormones. LH and FSH are secreted from cells in the anterior pituitary gland, and are called "gonadotropins" because of their role in stimulating the gonads.
The principle regulator of LH and FSH secretion is "gonadotropin-releasing hormone" (GnRH). GnRH is secreted from the hypothalamus. GnRH stimulates secretion of LH and FSH, which in turn stimulates gonadal secretion of the sex steroids testosterone, estrogen and progesterone (see diagram at left). In an example of a negative feedback loop, the presence of a certain level of sex steroids then inhibits further secretion of GnRH. Numerous hormones influence GnRH secretion, and feedback control over GnRH and LH/FSH secretion is quite complex.
Male Hormones and Sexual Development
The role of male hormones in the human body varies in different phases of a person’s life. These hormones are critical for the development of male traits during pre-birth and puberty but only work for the maintenance of reproductive function in mature adults.
Before Birth
A fetus develops into a male or female between the 12 and 17th week of pregnancy. It is during this period that the female or male sex organ is developed. During this period, the levels of the male hormone, testosterone is ten times higher in male fetuses than in female fetuses. From the transpiration of this period, the level of testosterone in males reduces and remains equal to that of the female until the onset of puberty.
During Puberty
During puberty the level of testosterone (male hormone) is slightly higher in boys than in girls. At the same time, the level of estrogen (female hormone) is much higher in girls than in boys. These differences in the hormonal balance contribute to the development of the secondary sexual characteristics.
Secondary characteristics in males are stimulated by testosterone. During puberty, the growth of the testicles, the appearance of pubic hair at the base of the penis, and an enlargement of the penis occur. These changes indicate that the male hormones are functioning properly and the body is smoothly reaching the age of maturity.
It triggers other bodily changes, making you:
- develop facial, pubic and chest hair
- become more muscular
- grow taller, broad-shouldered and heavier
- perspire more
- get oilier skin and pimples.
- develop facial, pubic and chest hair
- become more muscular
- grow taller, broad-shouldered and heavier
- perspire more
- get oilier skin and pimples.
Adulthood
Male sex hormones play a great role in the physical changes in adults too. For men, a decrease in the level of testosterone can lead to breast enlargement, loss of muscle size and strength and bone thinning or osteoporosis.
Circulating levels of male hormones can also influence human behavior. Androgen levels have been implicated in the regulation of human aggression and libido. Excessive testosterone in the system is usually the cause of aggressiveness and increased sexual activity.
Older Adults
Unlike women, who stop ovulating permanently after menopause, most men are fertile into old age, unless they have a medical problem. After age 40, it's normal for male testosterone levels to fall but, unlike estrogen levels in menopausal women, they fall very gradually. However, in some older men, testosterone levels get too low and may cause physical and emotional symptoms, including low libido, hot flushes, breast development and erection problems. Diagnosed correctly, this condition can be treated using medically supervised testosterone replacement therapy (TRT).
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