on MEN & WOMEN
Hormone info on men and women
The endocrine system is one of the main systems that the body has to control and coordinate the functioning of the organism. The endocrine system is made up of a great variety of glands, which are formed by different secretory cells surrounded by connective tissue that provides blood vessels, lymphatic capillaries, and nerves. The secretory portion of the gland is made up of specialized cells that produce the hormones (chemicals that act on different organs and tissues inducing a certain function).
The endocrine glands of the human body include the pituitary gland, the thyroid gland, the parathyroid glands, the adrenal glands, and the pineal gland. In addition, several organs contain endocrine tissue such as the hypothalamus, thymus, pancreas, stomach, liver, small intestine, kidneys, ovaries, and testes.
Hormones are secreted by the glands after a chemical or nervous stimulus and can develop their maximum action even in a few minutes. For example, adrenaline and noradrenaline are secreted after the stimulation of the sympathetic nervous system, reaching its maximum activity in 1 minute. Later these hormones are destroyed quickly so that their action does not last more than 1-3 minutes. Other hormones, such as thyroid hormones, are stored in the form of thyroglobulin in the thyroid gland even months before they are released into the bloodstream. Once the secretion of these hormones occurs, hours or even days required for the onset of action in target organs, but its effect, once produced, may last 4-6 weeks.
The vast majority of hormones are produced without distinction in both sexes. However, there are some hormones whose concentration is higher in men and others that are produced in greater proportion by women.
The ovaries (female genitalia) fulfill a quite important endocrine function by the synthesis of the female sex hormones, estrogen, and progesterone.
Estrogens are the most important hormones that influence the lives of women, are responsible for regulating the main female sexual characteristics such as the menstrual cycle and development of genitalia. There are three main forms of estrogen found in the human body: estrone, estradiol, and estriol, with estradiol being the most potent of these. The amount of estradiol in the blood varies according to the stage of the menstrual cycle of the woman. After menopause, the production of estradiol falls to a very low but constant level. Decreasing levels of estrogen during menopause predisposes the occurrence of hot flushes, osteoporosis, vaginal dryness, increased cholesterol levels, dry skin and decreased libido.
Mechanism of action
The specificity of the estrogenic action depends on the presence of intracellular receptors. It has been demonstrated the existence of these estrogen receptors in cells of the uterus, vagina, mammary glands, fallopian tubes, hypothalamus, pituitary, adrenal, testicle, kidney, among others. Due to its liposolubility, estrogens easily cross the cell membrane, and bind to the estrogenic receptor, forming the steroid-receptor complex. The conformational change allows the entry of estrogen into the nuclear compartment where it stimulates or suppresses the action of certain genes, which allows regulating the synthesis of various proteins.
Effects of estrogen
- Development of female sexual characteristics (breast growth, widening of the hips, bulbar growth, the appearance of the first menstruation)
- Maturation and development of the vaginal mucosa
- Stimulation of mucous secretion of the cervix. The estrogens modify the physicochemical characteristics of the cervical mucus, making it more fluid, which facilitates the passage of sperm through the cervix.
- Proliferation of endometrial tissue
- Increased fluid retention
- Decrease in blood cholesterol
- Stimulation the osteoblastic activity and therefore help an adequate bone mineralization.
Progesterone is the female hormone that is produced in the ovary in the second half of the sexual cycle. Physiologically, the secretion of progesterone is under the stimulatory control of luteinizing gonadotropin (LH), which activates the synthesis of the hormone in the ovarian follicle.
Mechanism of action
Like all steroids, progestagens have a receptor located inside the target cells to which they bind. The progestogen receptor complex is translocated to the nucleus where it acts on DNA to induce the synthesis of specific proteins.
Effects of Progesterone
- Stimulation of the glandular development of the endometrium which allows implantation of the embryo
- Modification of the physicochemical characteristics of the cervical mucus, making it more viscous, allowing the formation of a mucous plug that prevents the entry of microorganism into the uterus.
- Proliferation of breast acini (breast engorgement)
- Increase in blood colesterol
- Increase in body temperature
- Improvement of memory and cognitive capacity of the brain
The testes are responsible for secreting most of the androgens (male sex hormone) produced by the body. Androgens are steroid hormones whose main function is to stimulate the development of male sexual characteristics. The ovaries and adrenal glands can also produce small amounts of androgens. The main androgens are testosterone, androsterone, and androstenedione. The decrease in testosterone levels causes erectile dysfunction, loss of muscle tissue, depression, asthenia, insomnia, and irritability.
Mechanism of action of testosterone
Testosterone and androgens easily cross the cell membrane and bind to specific intracellular receptors inducing the synthesis of enzymes and cellular proteins. Testosterone is metabolized in some tissues by the enzyme 5-alpha-reductase generating Dihydrotestosterone which has a more potent effect than testosterone.
Effects of testosterone
- Development of male sexual characteristics (growth of the penis and testicles, change of tone of voice, growth of pubic hair)
- Increase in protein synthesis
- Increased muscle mass
- Maturation of sperm
- Stimulation of erythropoiesis (formation of red blood cells)
- Proliferation of sebaceous glands
- Fluid retention
- Hair loss