In: Anatomy and Physiology
Multiple Choice
1. Of the following, which hormone elicits sexual receptivity and increase of GnRH from the surge center?
a. inhibin
b. estradiol
c. progesterone
d. testosterone
2. Which of the following explain why androgens and estrogens have important functions in the bone growth?
a. They affect the Harvesian and Volkmann cannals
b. increase the generation and lifespan of osteoblasts and osteocytes
c. decrease the lifespan of osteoblasts
d. increase the generation and lifespan of osteoclasts
Ans1:- b) estradiol
Estrogen has a bimodal effect on the hypothalamus with both an inhibitory and stimulatory influence on GnRH secretion. The stimulatory effect of estrogen is seen at the end of the follicular phase where estrogen triggers the preovulatory GnRH surge. The ability of estrogen to induce a surge declines with age in female .) This appears to be due in large part to a decrease in estrogen induction of GnRH neurons, , although a decline in pituitary responsiveness to GnRH contributing to attenuated luteinizing hormone (LH) surges has also been proposed .
All other three hormones in the option only have negative feed back control on GnRH.
Ans2:- a. They affect the Harvesian and Volkmann cannals
Concept:- Estrogen help in bone remodeling . So it help in maturation and formation of harvesian and Volkmann canal.
Actually
Estrogen has been shown to inhibit osteoblast apoptosis and increase osteoblast lifespan ), thereby increasing the functional capacity of each osteoblast.
and estrogen and androgen induce apoptosis of osteoclast and decrease bone resorption.