Hormonal Control of Female Reproductive Functions

Hormonal Control of Female Secondary Sex Characteristics

1. The hypothalamus releases GnRH, which stimulates the anterior pituitary gland. 2. The anterior pituitary gland secretes FSH and LH. 3. FSH stimulates the maturation of a follicle; granulosa cells of the follicle produce and secrete estrogens. 4. LH stimulates certain ovarian cells to secrete estrogen precursor molecules. 5. Estrogens are responsible for the development and maintenance of most of the female secondary sex characteristics. 6. Concentrations of androgen affect other secondary sex characteristics, including skeletal growth and growth of hair. 7. Progesterone, secreted by the ovaries, affects cyclical changes in the uterus and mammary glands.

progesterone

A hormone produced by the ovaries which acts with estrogen to bring about the menstrual cycle. •Stimulates uterine changes during menstrual cycle. •Affects mammary glands. •Regulates secretion of gonadotropins.

corpus albicans

If fertilization does not occur, the corpus luteum involutes to form the corpus albicans that is filled with fibrous tissue. The secretory cells of the corpus luteum degenerate and are phagocytoses by macrophages.

corpus luteum

a mass of cells that forms in an ovary and is responsible for the production of the hormone progesterone during early pregnancy.

endometriosis

cause of female infertility •Endometrial tissue grows in abdominal cavity; fibrosis occurs, which may encase ovary or obstruct uterine tubes.

anovulation

cause of female infertility •Hyposecretion of FSH and LH from anterior pituitary, and resulting lack of ovulation.

infections

cause of female infertility •such as gonorrhea, which can obstruct uterine tube, or cause production of a viscous mucus that prevents sperm from entering uterine tube.

FSH and LH:

control oocyte maturation and production of female sex hormones

Gonadotropin-releasing hormone (GnRH):

secreted by hypothalamus; causes anterior pituitary to secrete FSH and LH.

Estrogens and Progesterone:

secreted by ovaries, adrenal cortices, and the placenta during pregnancy

menarche

the first menstrual period

Estrogens develop and maintain female secondary sex characteristics:

•Breast and mammary gland duct development. •Increased adipose tissue in breasts, thighs, buttocks. •Increased vascularization of skin.

Hormones secreted by the hypothalamus, the anterior pituitary gland, and the ovaries control the following reproductive processes:

•Development and maintenance of female secondary sex characteristics which are special features associated with the adult female body. •Maturation of female sex cells. •Changes during the menstrual cycle.

estrogens

•Stimulate enlargement of accessory reproductive organs. •Stimulate thickening of the endometrium.

menstrual cycle

•The menstrual cycle is characterized by regular, recurring changes in the endometrium of the uterus, which culminates in menstrual bleeding (menses). •This begins around age 13 and continues into early 50s. •Each month, regular, recurring changes also occur in the ovary, as one mature antral follicle is ovulated, and the remnants of the follicle close up to become the corpus luteum. •In the absence of fertilization, the oocyte degenerate, and then the corpus luteum also degenerates, becoming a corpus albicans.

menopause (female climacteric)

•The stopping of the menstrual cycles. •Usually occurs in the late 40s or the early 50s. •The ovaries no longer produce as much estrogens and progesterone as they did previously. •Some female secondary sex characteristics may disappear. •50% of women experience hot flashes. •Migraine headaches, backaches and fatigue occur in some women.

infertility

•inability to conceive a child after 1 year of trying. •Males and females contribute equally to infertility. •25% of cases due to more than one factor, according to the American Society for Reproductive Medicine.