What effect would low levels of testosterone have on the release of kisspeptin b

Question

What effect would low levels of testosterone have on the release of kisspeptin by neurons in the median eminence and on the release of GnRH? Select one:

a. Less kisspeptin would be released and more GnRH would be released

b. Less kisspeptin would be released and less GnRH would be released

c. More kisspeptin would be released and more GnRH would be released

d. More kisspeptin would be released and less GnRH would be released

Which of the following hormones would NOT be produced if you blocked the activity of 3beta-HSD? Check all the correct responses for full credit. Select one or more:

a. Testosterone b. Androstenediol c. Progesterone d. Estradiol e. Dehydroepiandrosterone (DHEA)

Which of the following changes would occur in the HPG axis if you castrated an adult man? Check all correct options for full credit. Select one or more:

a. LH release would increase b. GnRH release would increase c. GnRH release would decrease d. Testosterone release would increase e. Testosterone release would decrease f. LH release would decrease

Which of the following changes would take place if you removed the anterior pituitary of a man? Select one or more:

a. Testosterone release would increase b. FSH release would increase c. FSH release would decrease d. Testosterone release would decrease e. GnRH release would decrease f. GnRH release would increase

Which of the following can itself be aromatized to form an estrogen (i.e. no intermediate steps to form an androgen)? Select all correct options for full credit. Select one or more:

a. Androstenedione b. Progesterone c. Dihydrotestosterone (DHT) d. Androstenediol e. Testosterone

What effect does inhibin have on testosterone synthesis? Select one:

a. It inhibits the release of testosterone by impairing LH release b. It can stimulate an increase in testosterone release by itself c. It enhances the effects of LH, thereby increasing testosterone release d. It has no effect on testosterone production or release; inhibin only affects the release of FSH.

Release of which of the following hormones would INCREASE if you blocked inhibin release? Check all correct options for full credit. Select one or more:

a. DHT b. LH c. Testosterone d. GnRH e. FSH

What would happen to the release of GnRH and testosterone in a man if you injected him with LH? Select one:

a. Testosterone release would decrease and GnRH release would increase b. Both testosterone and GnRH release would increase c. Both testosterone and GnRH release would decrease d. Testosterone release would increase while GnRH release would decrease

Explanation / Answer

Question 1: What effect would low levels of testosterone have on the release of kisspeptin by neurons in the median eminence and on the release of GnRH?
Answer is: c. More kisspeptin would be released and more GnRH would be released
Explanation: Kisspeptin belongs to a family of neuropeptides that act as 'upstream regulators' of GnRH neurons. Hence, a low level of testosterone would stimulate the kisspeptin to upregulate the GnRH to produce testosterone to meet the required threshhold level in the blood.

Question 2: Which of the following hormones would NOT be produced if you blocked the activity of 3beta-HSD?
Answer: All of the above.
Explanation: The enzyme 3beta-HSD literally controls the steroidogenic reactions in the adrenal cortex, gonads, placenta and other target tissues.

Question 3: Which of the following changes would occur in the HPG axis if you castrated an adult man?
Answer: LH release would increase, GnRH release would decrease, Testosterone release would decrease

Question 4: Which of the following changes would take place if you removed the anterior pituitary of a man?
Answer & Explanation: FSH release would decrease (since Anterior pituitary produces this, hence FSH levels decrease), Testosterone release would decrease (Due to decrease in FSH levels, testosterone levels also derease), GnRH release would increase (Since there would be no negative feedback inhibition to inhibit its release)

Question 5: Which of the following can itself be aromatized to form an estrogen (i.e. no intermediate steps to form an androgen)?
Answer & Explanation: Androstenedione & Testosterone can aromatize themselves to estrogen in the liver and placenta.

Question 6: What effect does inhibin have on testosterone synthesis?
Answer & Explanation: It has no effect on testosterone production or release; inhibin only affects the release of FSH. Inhibin happens to be a peptide hormone secretd by the Sertoli cells of the gonads, which inhibits the secretion of FSH.

Question 7: Release of which of the following hormones would INCREASE if you blocked inhibin release?
Answer & Explanation: GnRH, since Inhibin reduces GnRH; FSH, since Inhibin inhibits the release of FSH

Question 8: What would happen to the release of GnRH and testosterone in a man if you injected him with LH?
Answer: Testosterone release would increase while GnRH release would decrease.
Explanation: This is because LH has no negative feedback effect on GnRH release. And testosterone release would increase due to an increase in LH.

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