1.2 Reproductive Hormones

Question 1

components of a neuroendocrine reflex arc

Answer 1

stimulus > sensory neurons > transmission > efferent neuron > hypothalamus > neurohormone > blood > target tissue > response by target tissue

Question 2

what pattern are reproductive hormones generally secreted in?

Answer 2

-pulsatile
- secreted periodically (female), in regular cycles, or constitutively (male).

Question 3

what do “releasing hormones” do?

Answer 3

control the release of other hormones/factors

Question 4

what do gonadotropic hormones do?

Answer 4

stimulate gonads

Question 5

biochemical hormone classsification

Answer 5

-peptides
-steroids
-fatty acid derivatives

Question 6

gonadal steroid synthetic pathway

Answer 6

cholesterol > pregnenolone > progesteron > testosterone > estradiol

Question 7

fate of steroid hormones after secretion

Answer 7

secretion by gonad > enters blood, moves to target tissue > causes change in target tissue > passes through liver > liver renders steroid water soluble > reenters blood, enters kidney or bile > excreted in urine or feces

Question 8

which part of the hypothalamus is sensitive to positive feedback? what would happen here if estradiol levels increased?

Answer 8

surge centre
-estradiol up > increase GnRH from hypothalamus > increase LH from pituitary > increased stimulation of terminal follicular development, ovulation, and early CL

Question 9

what part of the hypothalamus responds with negative feedback? what would happen here if progesterone and estradiol levels increased?

Answer 9

increased progesterone + estradiol > decreased GnRH from hypothalamus > decreased LH from pituitary > ovulation blocked

Question 10

what does LH do in the Theca cells? What does FSH do in granulosa cells?

Answer 10

LH acts on Theca cell - cholesterol > androgen
FSH acts on granulosa cell - androgen > estrogen

Question 11

GnRH - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 11

Biochem Classification - releasing factor, gonadotropin?
source - hypothalamus
Male target tissue - anterior pituitary lobe (ALP)
female target tissue - ALP
male primary action - release of FSH and LH from ALP
female primary action - Release of FSH and LH from ALP

Question 12

LH - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 12

Biochem Classification - glycoprotein
source - anterior pituitary
Male target tissue - Testis (interstitial cells of Leydig)
female target tissue - Ovary (theca interna and luteal cells)
male primary action - stimulates testosterone production
female primary action - Stimulates ovulation, CL formation and progesterone secretion

Question 13

FSH - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 13

Biochem Classification - protein
source - anterior pituitary
Male target tissue - Testis (sertoli cells)
female target tissue - Ovary (theca interna and luteal cells)
male primary action - stimulates testosterone production
female primary action - Stimulates ovulation, CL formation and progesterone secretion

Question 14

Prolactin - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 14

Biochem Classification - protein
source - anterior pituitary
Male target tissue - Testis and brain
female target tissue - mammary cells, CL in some species
male primary action - can induce maternal behaviour in males and females
female primary action - lactation, maternal behaviour

Question 15

oxytocin - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 15

Biochem Classification - peptide

source - Synthesized in hypothalamus, stored in PLP, also synthesized by CL

Male target tissue - smooth muscles of epididymis

female target tissue - Myometrium and endometrium of uterus, mammary gland

male primary action - pre-ejaculatory movement of spermatozoa

female primary action - uterine motility and milk ejection; luteolysis

Question 16

E2 - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 16

Biochem Classification - steroid

source - granulosa cells of follicles, placenta, sertoli cells of testis

Male target tissue - brain, inhibits long bone growth

female target tissue - hypothalamus, entire repro tract and mammary gland

male primary action - sexual behaviour, sperm production and epididymis function

female primary action - sexual behaviour, elevates secretory activities of the entire repro tract, elevates uterine motility

Question 17

P4 - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 17

Biochem Classification - steroid

source - corpus luteum and placenta, adrenal gland?

Male target tissue - ?

female target tissue - uterine myometrium, endometrium, mammary gland

male primary action - ?

female primary action - maintenance of pregnancy

Question 18

T - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 18

Biochem Classification - steroid

source - leydig cells (male), theca iinterna cells (female)

Male target tissue - accessory sex glands

female target tissue - brain, ganulosa cells

male primary action - anabolic growth, spermatogenesis, secretion of accessory glands

female primary action - substitute for estradiol, synthesis, abnormal sex characteristics

Question 19

inhibin - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 19

Biochem Classification - glycoprotein

source - granulosa cells (female), sertoli cell (male)

Male target tissue - ALP

female target tissue - ALP, ovary

male primary action - inhibits FSH secretion

female primary action - inhibits FSH secretion

Question 20

inhibin - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 20

Biochem Classification - glycoprotein

source - granulosa cells (female), sertoli cell (male)

Male target tissue - ALP

female target tissue - ALP

male primary action - stimulates FSH secretion

female primary action - stimulates FSH secretion

Question 21

PgE2 - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 21

Biochem Classification - prostoglandin

source - ovary, uterus, embryonic membranes

Male target tissue - ?

female target tissue - CL, oviduct

male primary action - ?

female primary action - ovulation, stimulates progesterone production from CL

Question 22

PgF2a - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 22

Biochem Classification - prostaglandin

source - uterus, vesicular glands

Male target tissue - epididymis

female target tissue - CL, uterus, ovarian follicles

male primary action - affects metabolic activity of sperm

female primary action - ovulation, luteolysis

Question 23

Equine chorionic gonadotropin (eCG) - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 23

Biochem Classification - glycoprotein

source - chorionic girdle cells

Male target tissue - NA

female target tissue - ovary

male primary action -

female primary action - causes formation of corpus lutea

Question 24

Human chorionic gonadotropin (hCG) - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 24

Biochem Classification - glycoprotein

source - trophoblast of blastocyst

Male target tissue - NA

female target tissue - ovary

male primary action - increase growth of fetal testis

female primary action - facilitate production of progesterone by ovary

Question 25

Placental lactogen - biological classification, source, male target tissue, female target tissue, male primary action, female primary action

Answer 25

Biochem Classification - protein

source - placenta

Male target tissue - NA

female target tissue - mammary gland of dam

male primary action - NA

female primary action - mammary gland stimulation

Question 26

mechanism of action for protein hormones

Answer 26

protein hormones act via plasma membrane receptor

1 Binding of hormone to receptor
2 Activation of adenylate cyclase
3 Activation of protein kinase
4 Synthesis of new products

Question 27

mechanism of action of steroid hormones

Answer 27

steroid hormones act via nuclear receptors

1. Transport of steroid
2. Transfer through cell membrane and cytoplasm
3. Binding of steroid to the nuclear receptor
4. Synthesis of mRNA and protein