Passage The Adrenal Glands Are Divided into Two Anatomically Distinct Regions

Passage
The adrenal glands are divided into two anatomically distinct regions, the adrenal medulla and the adrenal cortex.  The adrenal medulla is a collection of irregularly shaped cells located in the interior portion of each adrenal gland.  In response to changing serum levels of corticosteroid hormones, medullary cells synthesize and secrete the catecholamines norepinephrine and epinephrine.  Norepinephrine and epinephrine are water-soluble compounds, and their actual secretion into the bloodstream is stimulated by acetylcholine (ACh) -mediated signaling in the sympathetic component of the autonomic nervous system.  Figure 1 shows the enzyme-mediated synthesis of norepinephrine and epinephrine.
Figure 1The adrenal cortex is the outer portion of the adrenal gland and is composed of cells that synthesize and secrete lipophilic hormones derived from cholesterol.  Hormones produced by the adrenal cortex include the principal glucocorticoid hormone (cortisol) and the mineralocorticoid hormone (aldosterone) .The hypothalamus and pituitary gland regulate and control the endocrine functions of the adrenal cortex (Figure 2) .  Secretion of corticotrophin-releasing hormone (CRH) from the hypothalamus promotes the synthesis and release of adrenocorticotrophic hormone (ACTH) by the pituitary gland.  ACTH acts on adrenal cortex cells to promote the growth of cortical tissue and to increase the synthesis and secretion of glucocorticoids.  In addition to its body-wide functions as the principal stress hormone, cortisol also regulates adrenal activity by inhibiting CRH release from the hypothalamus and ACTH release from the pituitary.
Figure 2
-A woman with low serum cortisol due to partial adrenal dysfunction is treated with high doses of a synthetic cortisol analogue.  According to Figure 2, treatment with a cortisol analogue will most likely cause this patient's serum level of endogenous cortisol to:

A) increase only.
B) decrease only.
C) remain the same.
D) increase at first, but then decrease over time.

Correct Answer:

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