MCAT Behavioral Sciences Question 187: Answer and Explanation
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Question: 187
7. Cortisol has a direct inhibitory effect on:
- A. the posterior pituitary.
- B. the hypothalamus.
- C. the adrenal cortex.
- D. glycogen mobilization.
Correct Answer: B
Explanation:
The hypothalamic-pituitary axis (HPA) regulates the release of cortisol via negative feedback. The hypothalamus releases corticotropin releasing hormone (CRH), which stimulates the anterior pituitary to release adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal cortex to release cortisol. Cortisol then inhibits the hypothalamus from releasing further CRH and the anterior pituitary from releasing more ACTH, thus having an inhibitory effect on both (choice B is correct). The posterior pituitary releases oxytocin and antidiuretic hormone; cortisol does not inhibit the posterior pituitary (choice A is wrong). Additionally, cortisol does not inhibit the adrenal cortex directly, but rather inhibits the hypothalamus and anterior pituitary from releasing the hormone that stimulate the adrenal cortex; thus cortisol has an indirect inhibitory effect on the adrenal cortex (choice C is wrong). Cortisol stimulates glycogen mobilization (choice D is wrong).