Week 8 - Reproductive Hormones

Question 1

What is the rate limiting step of steroid hormone synthesis?

Answer 1

moving pregnenolone into the endoplasmic reticulum

Question 2

What are the three layers of the adrenal cortex from superficial to deep?

Answer 2

zona glomerulosa

zona fasiculata

zona reticularis

Question 3

What is produced in the zona glomerulosa?

Answer 3

aldosterone (mineralocorticoid)

outermost layer of the adrenal cortex

Question 4

What is the role of aldosterone in the body?

Answer 4

long term regulation of blood pressure

acts on distal convoluted tubule and collecting ducts of kidney where is causes increased reabsorption of sodium

Question 5

What is produced by the zona fasiculata?

Answer 5

cortisol (glucocorticoid)

middle layer of the adrenal cortex

Question 6

What is produced by the zona reticularis?

Answer 6

androgens

innermost layer of adrenal cortex

Question 7

What is the role of dihydrotestosterone (DHT) in embryonic development?

Answer 7

causes differentiation of the penis, scrotum and prostate

type of androgen

Question 8

What is the role of DHT in later life?

Answer 8

contributes to male balding, prostate growth and sebaceous gland activity

Question 9

What is the role of androstenedione and dehydroepiandrosterone (DHEA)?

Answer 9

testosterone precursors

adrenal glands produce these molecules which are converted to testosterone in the peripheral tissues

Question 10

What is Addison’s disease?

Answer 10

deficiency in adrenal gland production of cortisol

leads to loss of body hair and libido

muscle wasting and thin limbs

Question 11

What is Cushing’s disease?

Answer 11

elevated levels of ACTH (adrenocorticotropic hormone) due to a pituitary adenoma

Question 12

How does cortisol exert it’s actions?

Answer 12

binds an internal receptor for transcription effects

Question 13

What is the site of sperm formation?

Answer 13

seminiferous tubules

Question 14

Which cells are responsible for secreting testosterone?

Answer 14

leydig cells

Question 15

What hormone stimulates the leydig cells to produce testosterone?

Answer 15

LH

increases conversion of cholesterol to pregnenolone

Question 16

What hormone acts on Sertoli cells to stimulate spermatozoa development?

Answer 16

FSH

also produces inhiin for negative feedback on FSH

Question 17

In men, where is most dihydroxytestosterone (DHT) produced?

Answer 17

Sertoli cells

sertoli cells convert testosterone to DHT or oestradiol

DHT is produced by the action of 5-alpha-reductase on testosterone

FSH increases activity of this enzyme

Question 18

What hormone negatively feeds back to the hypothalamus, inhibiting further release of GnRH, LH and FSH?

Answer 18

testosterone

inhibin negatively feedsback to the anterior pituitary NOT hypothalamus directly

in women, oestradiol controls GnRH release

Question 19

What is the genital phenotype of male patients who cannot produce any DHT?

Answer 19

male internal, ambiguous external

DHT is needed for development of external genitalia only

Question 20

What happens to the genitalia of a baby in the absence of DHT?

Answer 20

female external genitalia will form regardless of other factors

Question 21

What is androgen sensitivity syndrome (AIS)?

Answer 21

mutation in the gene AR which normally makes an androgen receptor

body does not respond to androgens so the external genitalia of the child appear female even though they are genetically male

Question 22

What is the action of testosterone and DHT on secondary sexual characteristics?

Answer 22

promotes muscle growth

induces male hair growth pattern

causes the voice to deepen (vocal chord thickening)

Question 23

What is the mechanism of action of the enzyme aromatase?

Answer 23

aromatisation of androgens to estrogens

Question 24

In men, where is most DHT produced?

Answer 24

Sertoli cells by the action of 5-alpha reductase on testosterone