Author: Tan Xianjie (Peking Union Medical College Hospital)
The ovaries are the female gonads, small but dominant in a woman’s life.
During the period of strong ovarian function, it dominates the appearance of female characteristics, controls women’s menstrual cramps, and helps women complete reproductive function. When the ovaries gradually decline, women also gradually menopause and age.
A woman’s ovaries produce 3 sex hormones: estrogen, progesterone, and androgens. These 3 sex hormones are crucial to women’s menstrual cramps and reproductive function.
One, the function of androgens
Don’t think that androgens are only available in men, and are also one of the essential sex hormones for women. They are not only the raw material for synthesizing estrogen, but also an important hormone for maintaining women’s physiological functions.
It can promote protein synthesis, participate in bone growth and calcification of long bones (ie epiphysis healing), participate in water and salt metabolism, stimulate erythrocyte proliferation in bone marrow, and promote hematopoiesis.
Androgens can also maintain normal female reproductive function and sexual desire, promote the development of the clitoris, labia, mons pubis, and pubic hair, and have a direct effect on the female sexual behavior center, which means that it will Helps generate sexual drive, libido.
However, if the secretion of androgen is too much, too much stamina, causing women to experience symptoms such as hirsutism, amenorrhea, acne, etc., you need to be alert to a disease called “polycystic ovary syndrome”.
Image source: Zhanku Hailuo
Second, the function of estrogen
The reason why women have different postures, voices and personalities than men is related to estrogen in their bodies, so estrogen was formerly known as “feminine” and “estrogen”. It maintains the secondary sexual characteristics of women, and has done enough homework for women’s pregnancy and childbirth.
First, estrogen comes from the ovary, but it also regulates ovarian function. It promotes the early development of follicles, regulates the secretory function of follicles and ovulation. If estrogen is insufficient, the follicles will stop developing and atresia, resulting in menstrual disorders, amenorrhea, infertility, etc., affecting the physiological function of women.
Secondly, estrogen can promote uterine development, thicken the uterine muscle wall, increase blood flow, proliferate cells in the functional layer of the endometrium, prepare soil for embryonic development; it can also soften the cervix Dilated, increased mucus, thinning. This allows the sperm to penetrate the cervix smoothly and combine with the egg.
Again, estrogen can promote the development and contraction of the fallopian tube myometrium, increase the secretion of luminal epithelial cells, promote the growth of cilia, and enhance the ability of the fallopian tube to swing towards the uterus.
Finally, estrogen promotes the growth and development of the mammary gland stroma and glandular ducts, stimulates the secretion of prolactin from the pituitary gland, promotes milk production, and prepares rations for the possible birth of newborns.
Three, the role of progesterone
Progesterone and estrogen work closely together to help women accomplish their reproductive tasks.
First, progesterone inhibits the contraction of the myometrium, reducing its sensitivity to oxytocin, so that the uterus does not suffer from frequent “mini-quakes”, allowing the embryo to have a stable living environment .
Secondly, progesterone can counteract the proliferative effect of estrogen in the endometrium, make the gland secrete, and change the interstitial properties. In other words, it is to make the soil more fluffy, which is conducive to the implantation and development of pregnant eggs.
Again, progesterone can inhibit the secretion of mucus from the cervical glands, making it thicker and less smooth, which is not conducive to sperm penetration, allowing the embryo to exclusively occupy the uterus and prevent other sperm from coming to make trouble. .
Finally, progesterone, along with prolactin, promotes acinar development in preparation for milk production, which prepares rations for the soon-to-be-born fetus.
Image source: Zhanku Hailuo
Female reproductive endocrine axis
In fact, the development of various stages of a woman’s life, as well as her reproductive function, are precisely regulated by these hormones. The in vivo system that regulates the above process is called the “reproductive endocrine axis”, that is, the “hypothalamus-pituitary-ovarian axis”, which consists of three levels of hypothalamus, pituitary and ovary.
1. Hypothalamus
Located at the base of the brain, it is a neuroendocrine organ. Certain neuronal cells in the hypothalamus have dual functions, both transmitting nerve impulses and secreting a variety of hormones.
Gonadotropin-releasing hormone is directly related to the physiological function of the female reproductive endocrine system. After this hormone is released, it reaches the anterior pituitary through the blood vessels in a pulsed (ie intermittently) manner to stimulate the pituitary. The gonadotropins in the anterior lobe secrete the corresponding hormones in the secretion system.
2. Pituitary
Located in the pituitary fossa formed by the sphenoid bone at the base of the brain and divided into anterior and posteriorlobes, in which there are gonadotropins in the anterior pituitary gland.
The hypothalamus releases gonadotropin-releasing hormone, which in turn stimulates gonadotropins to secrete two gonadotropins, one is follicle-stimulating hormone, which stimulates the growth of follicles in the ovary development and granulosa cell proliferation, and with the participation of a small amount of luteinizing hormone, the follicles secrete estrogen;
The second is luteinizing hormone, which can lead to mature follicle ovulation, corpus luteum formation and secretion of estrogen and progesterone under the influence of a certain proportion of follicle-stimulating hormone.
Image source: Zhanku Hailuo
3. Ovaries
The ovary is the organ that acts on hormones secreted by the pituitary gland and is called the “target organ”.
In the female reproductive endocrine axis, although the ovary has the lowest status, which is equivalent to performing tasks, that is, specific work, it can affect the endometrium, cervix, and vagina. Form and function, such as affecting menstrual cramps, reproductive function, etc.
The above three parts of the organization form a closed automatic feedback system under the control of the central nervous system. The hypothalamus is equivalent to the commander, the pituitary gland is equivalent to the transducer, and the ovary is equivalent to the actuator.
The ovary as the executor also has biphasic functions. One is to make the follicles produce estrogen and progesterone during the growth and development process. Under the action of the two hormones, the function of the reproductive organs is improved The second is that estrogen and progesterone feed back to change the secretory activity of the hypothalamus, promoting or inhibiting the secretory function of the hypothalamus.
Actually, the relationship between the three in the reproductive endocrine axis is mutual regulation and mutual restriction, the purpose is to keep the female reproductive endocrine system relatively stable, which is manifested in the comparison of ovulation and menstruation Strict rules and maintain female reproductive function.
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