Female Sex Hormones and the Menstrual Cycle

Flashcards about female sex hormones, menstrual cycle, and menopause.

What are the main female sex hormones?

Estrogen and progesterone

Which organ primarily produces estrogen and progesterone in females?

Ovaries

What are the three types of estrogens the female body can synthesize?

Estradiol, estrone, and estriol

Which of the three estrogens is the most biologically active?

Estradiol

Besides the ovaries, what other tissues produce small amounts of estrogen?

Adrenal cortex and fat cells in adipose tissue

What hormone does the hypothalamus secrete before puberty?

Gonadotropin-releasing hormone (GnRH)

What two hormones does the pituitary secrete in response to GnRH?

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

What structures in the ovaries develop and secrete hormones in response to FSH and LH?

Ovarian follicles

What cells are responsible for the synthesis of progesterone and estrogen within the ovarian follicles?

Theca cells and granulosa cells

What is the average length of the menstrual cycle?

28 days

What are the four phases of the menstrual cycle?

Follicular phase, luteal phase, ovulation phase, menstrual

Which hormone is primarily produced during the follicular phase?

Estrogen

Which hormone is dominant during the luteal phase?

Progesterone

What effect does estrogen have on the endometrium during the follicular phase?

Thickens up and sprouts progesterone receptors

Does estrogen act as a positive or negative feedback signal on FSH secretion during the follicular phase?

Negative feedback

Does estrogen act as a positive or negative feedback signal right before ovulation?

Positive feedback

What effect does progesterone have on the endometrial glands during the luteal phase?

Stimulates the endometrial glands to produce more secretions

What molecule is the precursor for both estrogen and progesterone?

Cholesterol

Which enzyme converts cholesterol to pregnenolone in the theca cells?

Cholesterol desmolase

Which enzyme converts testosterone into 17-beta-estradiol in the granulosa cells?

Aromatase

What plasma protein binds and carries 17-beta-estradiol in the blood?

Sex hormone-binding globulin (SHBG)

What enzyme is up regulated during the luteal phase and converts cholesterol to pregnenolone in granulosa cells?

P450scc (cholesterol side-chain cleavage enzyme)

What are the local effects of estrogen and progesterone?

Maturation of female reproductive organs and secondary sex characteristics

What are the systemic effects of estrogen?

Protects the cardiovascular system and sustains bone density

What is the role of the placenta with estrogen and progesterone during pregnancy?

Maintains pregnancy and prepares breasts for lactation

Which type of estrogen is predominantly produced during pregnancy?

Estriol

Which type of estrogen is the dominant kind after menopause?

Estrone