Reproductive Physiology

Question 1

What kind of cell secrete progesterone?

Answer 1

Theca cells in the ovaries.

Question 2

What kind of cells secrete estradiol?

Answer 2

Theca cells together with granulosa cells in the ovaries secrete estradiol.

Question 3

Development of Wolfian ducts depends on?

How about external male genitalia?

Answer 3

Testosterone acts on the wolfian ducts and do not have to be converted to DHT to do so. External male genitalia differentiates at week 9th-10th, it depends on conversion of testosterone to DHT and the presence of androgen receptors on target tissues.

Question 4

What happens to hormone levels in senescence?

Answer 4

Gonadotropin secretion rates increase further, with FSH levels becoming higher than LH, as they were in childhood.

Question 5

What is adrenarche?

Answer 5

Female, the appearance of pubic and axillary hair that precedes menarche and is dependent on increased secretion of adrenal androgens.

Question 6

What are two ways that prostaglandins contribute to fertilization?

Answer 6

Prostaglandins present in seminal fluid may assist in fertilization in two ways:

1. They react with cervical mucus to make it more penetrable by sperm.
2. Prostaglandins induce peristaltic contractions in the female reproductive tract to propel the sperm up the tract.

Question 7

What enzyme converts androstenedione to testosterone in testes?

Answer 7

17, Beta-hydroxysteroid dehydrogenase, converts androstenedione to testosterone.

Question 8

What protein binds testosterone?

Answer 8

98% of it is bound to sex steroid binding globulin and albumin. Since only free testosterone is biologically active, sex steroid-binding globulin essentially functions as a reservoir for the circulating hormone.

Question 9

What secretes GnRH?

Answer 9

It is secreted by hypothalamic neurons in the arcuate nuclei.

Question 10

What cells do FSH and LH stimulate?

Answer 10

FSH stimulate spermatogenesis and sertoli cells function. LH stimulates leydig cells to synthesize testosterone by increasing the cholesterol desmolase activity.

Question 11

What enzyme converts cholesterol to pregnenolone?

Answer 11

Cholesterol desmolase.

Question 12

What is the action of Inhibin

Answer 12

Glycoprotein that is feedback inhibitor of FSH secretion by the anterior pitiutary. It is secreted by sertoli cells.

Question 13

What is the action of 5-alpha-reductase inhibitors? (Finasteride)

Answer 13

They inhibit the conversion of testosterone to DHT. B/c growth of the prostate gland and male pattern baldness depend on DHT, rather than testosterone, these inhibitors can be used as tx for benign prostatic hypertrophy and hair loss in males.

Question 14

what is the corpus luteum composed of?

Answer 14

the copus luteum is composed primarily of granulosa cells but also of theca cells, capillaries, and fibroblast.

Question 15

what is the corpus albicans?

Answer 15

The residual elements of the ruptured primary follicle form the copus luteum. This is composed primarily of granulosa cells but also of theca cells, capillaries, and fibroblast. If fertilization does not occur the corpus luteum regress during the next 14 days and is replaced by a scar called the corpus albicans.

Question 16

What cells in the follicle have FSH receptors?

Answer 16

The granulosa cells are the only ovarian cells with FSH receptors.

Question 17

Is the follicular phase dominated by negative or positive feedback?

Answer 17

Negative feedback, the actions of estradiol is negative feed. on the anterior pituitary cells to inhibit further secretion of FSH and LH.

Question 18

During the luteal phase, what is the major hormonal secretion?

Answer 18

Progesterone. It inhibits FSH and LH through neg. feed.

Question 19

In females, what type of cells produces inhibin?

Answer 19

Granulosa cells, it inhibits FSH secretion from the anterior pituitary.

Question 20

What is the function of activin, who secretes it?

Answer 20

It is secreted by ovarian granulosa cells and stimulates FSH secretion.

Question 21

What up-regulates progesterone receptors?

Answer 21

There is an up-regulation of progesterone receptors by estrogen. Without estrogen, progesterone has little biologic activity.

Question 22

What hormone blocks the actions of prolactin on breast?

Answer 22

Estrogen. But estrogen stimulates prolactin secretion.

Question 23

What is the effect of estrogen on fallopian tubes?

What is an antagonist?

Answer 23

It stimulates ciliary activity and contractility, aiding in the movement of sperm toward the uterus.

Progesterone , decreases contractility and increases secretory activity.

Question 24

What are the effect of progesterone and estrogen in vagina?

Answer 24

In vagina, estrogen promotes proliferation of epithelial cells; progesterone stimulates differentiation but inhibits proliferation.

Question 25

What stimulates growth of the edometrium, growth of glands, and stroma, and elongation of the spiral arteries, which supply the endometrium?

Answer 25

Estradiol

Question 26

The development of breast is dependent on what hormone?

Answer 26

Estrogen. It also increases the amount of adipose tissue, giving the breasts their characteristic female shape. Progesterone collaborates with estrogen by simulating secretory activity in the mammary ducts.

Question 27

What hormone has a thermogenic action?

Answer 27

Progesterone has a thermogenic actin, increases the body temperature during ovulation.

Question 28

What are the sources of steroid hormones on first, 2nd and 3er trimester?

Answer 28

1- corpus luteum | 2/3- placenta.

Question 29

Where does fertilization takes place?

Answer 29

In the ampulla. Once the sperm penetrates the ovum, the second polar body is extruded and the fertilized ovum begins to divide.

Question 30

What should be the estrogen/progesterone ratio for implantation of the ovum to the endometrium.

Answer 30

The receptivity of the endometrium to the fertilized ovum is critically dependent on a low estrogen/progesterone ratio.

Question 31

What types of cell contribute to the fetal portion of the placenta?

Answer 31

Trophoblast. Invades the endometrium and forms an attachment to the maternal membranes.

Question 32

what are the actions of syncytiotrophoblast?

Answer 32

syncytiotrophoblast, whose function is to allow the blastocyst to penetrate deep into the endometrium.

Question 33

What "rescues" the corpus luteum from regression?

Answer 33

HCG hormone.

Question 34

What makes estraiol, major form of estrogen, during pregnancy?

Answer 34

Placenta, fetal adrenal cortex and liver. Cholesterol is supplied to the placenta from the maternal circulation and is converted to pregnenolone in the placenta. (Which a portion gets converted to progesterone). Pregnenolone then enters the fetal circulation and is converted to dehydroepiandrosterone-sulfate (DHEA-sulfate) in the fetal adrenal cortex. DHEA-sulfate is hydroxylated to 16-OH DHEA- sulfate in the fetal liver. This then crosses back to the placenta, where sulfatase enzymes revoles sulfate and aromatase converts it to estriol.

Question 35

How does prolactin inhibits ovulation?

Answer 35

By inhibiting GnRH secretion by the hypothalamus and FSH and LH secretion by pituitary.

Question 36

What happens during menopause?

Answer 36

Estrogen secretion ceases, and there is reduced negative feedback on the anterior pituitary and accordingly increased secretion and pulsatility of FSH and LH at menopause. Women take estrogen replacement therapy to minimize the symptoms.