Block 13 Adrenal Gland Disorders MCQ's

5α-reductase is an enzyme that plays a crucial role in the conversion of testosterone into dihydrotestosterone (DHT). DHT is a highly potent androgen that is responsible for the development and maintenance of male secondary sexual characteristics, such as facial hair growth, deepening of the voice, and enlargement of the prostate gland. In individuals with 5α-reductase deficiency, the conversion of testosterone to DHT is impaired, leading to incomplete or abnormal sexual development during childhood. Therefore, the correct answer is "Turns testosterone into highly potent dihydrotestosterone."

The patient's symptoms of lethargy, nausea, muscle weakness, along with the abnormal levels of plasma corticotropin, cortisol, renin, aldosterone, and adrenal androgens, are consistent with Addison's Disease. Addison's Disease is a condition where the adrenal glands do not produce enough cortisol and aldosterone. The elevated plasma corticotropin is a compensatory response by the body to try and stimulate cortisol production. The low levels of adrenal androgens further support the diagnosis of Addison's Disease. Cushing's Disease, ectopic corticotropin-producing tumor, secondary renal insufficiency, and congenital adrenal hyperplasia would not typically result in the combination of symptoms and hormone abnormalities seen in this patient.

Polyuria and polydipsia are classic symptoms of diabetes mellitus, as the high levels of glucose in the blood cause the kidneys to produce more urine, leading to increased thirst. Weakness and fatigue can also be symptoms of diabetes mellitus, as the body's cells are unable to effectively use glucose for energy. Peripheral neuropathy, which is damage to the nerves in the extremities, and visual changes can also occur in diabetes mellitus due to the long-term effects of high blood sugar on the nerves and blood vessels. Therefore, diabetes mellitus is the most likely clinical condition to produce all six of these findings.

The hormone produced by the zona reticularis is Androstenedione. The zona reticularis is one of the three layers of the adrenal cortex, which is responsible for the production of various hormones. Androstenedione is a precursor hormone that is converted into testosterone and estrogen in both males and females. It plays a role in the development of secondary sexual characteristics and is involved in the regulation of the reproductive system.

The combination of hypersecretion of CRH and ACTH, along with hyposecretion of cortisol, would be the most likely given this man's signs and symptoms. This is because the symptoms of unusual fatigue, lightheadedness, postural hypotension, and darker-than-usual complexion are consistent with adrenal insufficiency, which is caused by a deficiency in cortisol production. The hypersecretion of CRH and ACTH can be a compensatory response by the body to try to stimulate cortisol production. The hyponatremia, hyperkalemia, and hypocalcemia seen in the lab work can also be explained by the lack of cortisol's regulatory effects on these electrolytes.

Calcium's influx is an absolute requirement for epinephrine secretion in the chromaffin cells of the adrenal medulla. Calcium acts as a crucial signaling molecule that triggers the fusion of vesicles containing epinephrine with the cell membrane, allowing the release of epinephrine into the bloodstream. Without the influx of calcium, this secretion process cannot occur, highlighting the importance of calcium in regulating the release of epinephrine.

Cortisol stimulates the conversion of norepinephrine to epinephrine in the synthesis of adrenal medullary hormones.

The expected outcome of 11-deoxycorticosterone-induced hypervolemia and hypertension on the renin-angiotensin-aldosterone system would be a decrease in renin, angiotensin II, and aldosterone levels. This is because 11-deoxycorticosterone is a mineralocorticoid hormone that acts similarly to aldosterone. When there is an excess of mineralocorticoids like 11-deoxycorticosterone, it suppresses the release of renin, which in turn decreases the production of angiotensin II and aldosterone. Therefore, the correct answer is B.

During stress and anxiety, cortisol stimulates the enzyme PNMT (phenylethanolamine-N-methyl transferase) to increase the synthesis of epinephrine. PNMT is responsible for converting norepinephrine into epinephrine, which is a hormone and neurotransmitter that helps the body respond to stress. This increased synthesis of epinephrine helps to activate the body's fight-or-flight response, preparing it to deal with the stressful situation.

The correct answer is E. The sympathetic branch of the autonomic nervous system elicits catecholamine release from the adrenal medulla. Acetylcholine is the neurotransmitter responsible for increased epinephrine release from adrenal medullary chromaffin cells, and the receptor involved is the nicotinic receptor.