Sex Hormones

Question 1

Sex steroids are derivatives of?

Answer 1

Cholesterol (like all steroids)

Question 2

What is the rate limiting step in steroid hormone synthesis?

Answer 2

side chain cleavage

Question 3

What enzyme converts Pregnenolone to Progetsterone?

Answer 3

3B- Hydroxysterone beta dehydrogenase

Question 4

Androstenedione gives rise to

Answer 4

Testosterone

Question 5

Testosterone gives rise to

Answer 5

Estradiol

Question 6

60% of seminal volume comes from where and consists of what?

Answer 6

Bulbourethral glands, seminal vesicles

-contains prostaglandins, fructose, citric acid

Question 7

Semen =

Answer 7

sperm + secretions mainly from SV(60%) and Prostate (20%)

Question 8

What pubertal changes are reversible?

Answer 8

spermatogenesis; size, secretion, content( fructose and citrate) of the sex accessory glands.

Question 9

Non-reversible changes

Answer 9

voice, height, beard growth, libido, muscle mass

Question 10

Two major functions of testis

Answer 10

gametogenesis and steroid production

Question 11

sperm produced where?

Answer 11

seminiferous tubules

Question 12

Testosterone produced where?

Answer 12

Leydig Cells

Question 13

Spermatogenesis requires what hormones?

Answer 13

FSH, Testosterone (high conc)

Question 14

Indirectly need:

Answer 14

LH for testosterone and GNRH for the production of FSH and lH

Question 15

What are Sertoli cells?

Answer 15

The stimulate spermatogenesis and are the site of action of FSH and Testosterone.

• They provide nutrients to developing sperm and provide a blood brain barrier to many chemicals
• secrete inhibin
• phagocytose dead or developing

Question 16

What is inhibin and where is it produced?

Answer 16

It is a hormone that is needed to decrease FSH

Question 17

LH secretion occurs in what kind of pattern?

Answer 17

Pulsatile

Question 18

LH secretion is required for what?

Answer 18

Testosterone production

Question 19

Some tissues require testosterone to be metabolized to what?

Answer 19

Dihydrotestosterone (must become DHT) in order to reach the nucleus and produce androgenic actions

Question 20

Examples of tissues that require transformation to DHT?

Answer 20

fetal formation of prostate and external genitalia
- pubertal enlargement of prostate, hair changes, acne

Processes that do not require change?
- pubertal growth of muscle, penis, scrotum

Question 21

Testosterone is degraded by what organ?

Answer 21

Liver…excreted in the urine

Question 22

Conversion to estradiol occurs where

Answer 22

adipose tissue, pituitary, hypothalamus

Question 23

How is testosterone transported in teh blood?

Answer 23

Gonadal steroid binding globulin

- sex hormone binding globulin (70%)

Question 24

How much T is free at any given time

Answer 24

3%

Question 25

Actions of testosterone

Answer 25

- fetal differentiation of male sex organs - induce changes in tissues at puberty - Maintain size and function of most male ACCESORY organs ( seminal vesicles, prostate, increase fructose content, volume of secretions) - Stimulate spermatogenesis - Stimulate protein anabolism and long bone growth - sex drive - feedback to inhibit LH - thick secretions (acne) - pubic, axillary, facial hair growth

Question 26

See slide on negative feedback.

Answer 26

ok. Important to note that testosterone feeds back to downregulate secretion of LH and FSH but it takes a ton of testosterone to downreulate FSH to bodybuilders know when they overdose because FSH decreases and size of testes decreases due to decrease in size of semeinferous tubules

Question 27

Primary sex organs in the female?

Answer 27

Ovaries

Question 28

Secondary Sex organs

Answer 28

oviducts, uterus, vagina | Glands: mucous and mammary

Question 29

Estrogen

Answer 29

Stimulates growth and formation of ovaries and follicles

Question 30

Low estrogen does what to LH and FSH?

Answer 30

inhibitory

Question 31

Rising estrogen

Answer 31

stimulatory, leads to mid cycle LH burst that causes ovulation

Question 32

very high E

Answer 32

inhibitory ...used to be used as BC

Question 33

very low E + progesterone

Answer 33

birth control pills

Question 34

What effect does E hav eon teh muscle and endothelial surfaces of the oviducts, uterus, vagina

Answer 34

Oviduct: growth of muscle and epithelium - motility - ciliary beating Uterus: Myometrium growth, contractility

Question 35

Cervical mucus

Answer 35

production of thin, watery, clear mucus

Question 36

Vagina stimulates growth of mammary glands, branching of ducts, fat deposition, nipples and areolae growth and darkening

Answer 36

ok