Block 13 Adrenal Gland Disorders MCQ's

1.

A predominantly male patient mentions that his childhood sexual development was a bit turbulent because of 5α-reductase deficiency. What is the function of 5α-reductase?

A.

Makes testosterone in the testis
B.

Is needed for the synthesis of glucocorticoids and mineralocorticoids
C.

Turns testosterone into highly potent dihydrotestosterone
D.

Turns androgens into estrogens
E.

Catalyzes the conversion of cholesterol into pregnenolone

Correct Answer
C. Turns testosterone into highly potent dihydrotestosterone

Explanation
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."

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2.

A 48 YO man with a family history of heart disease has followed a heart-healthy lifestyle for 15 years. However, he has recently experienced unusual fatigue and lightheadedness, especially when rising suddenly. Physical examination demonstrates postural hypotension and a darker-than usual complexion for midwinter in the Midwest (he works and exercises indoors). Lab work reveals that he is hyponatremic, hyperkalemic, and hypocalcemic. Further blood tests are ordered to assay plasma corticotropin-releasing hormone (CRH), corticotropin (ACTH), and cortisol. What combination of hyper and/or hyposecretion for these hormones would be the most likely given this man’s signs and symptoms? CRH secretion ACTH secretion Cortisol secretion A hypersecretion hypersecretion hypersecretion B hypersecretion hypersecretion hyposecretion C hypersecretion hyposecretion hyposecretion D hyposecretion hyposecretion hyposecretion E hyposecretion hyposecretion hypersecretion

A.

A
B.

B
C.

C
D.

D
E.

E

Correct Answer
B. B

Explanation
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.

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3.

A patient with lethargy, nausea, and reported muscle weakness is given a series of tests to rule out physical causes. During these tests it is revealed that plasma corticotropin is above normal and cortisol is below normal. Renin is above normal and aldosterone is below normal. Adrenal androgens are below normal. Which of the following clinical conditions would be most likely to produce this set of signs and symptoms?

A.

Cushing’s Disease
B.

Ectopic corticotropin-producing tumor
C.

Secondary renal insufficiency
D.

Congenital adrenal hyperplasia
E.

Addison’s Disease

Correct Answer
E. Addison’s Disease

Explanation
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.

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4.

Within the chromaffin cells of the adrenal medulla, which ion’s influx is an absolute requirement for epinephrine secretion?

A.

Calcium
B.

Sodium
C.

Chloride
D.

Potassium
E.

Iodide

Correct Answer
A. Calcium

Explanation
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.

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5.

What would be an expected outcome of 11-deoxycorticosterone-induced hypervolemia and hypertension on the renin-angiotensin-aldosterone system? [renin]_Pl [angiotensin II]_Pl [aldosterone]_Pl A Increase () Increase () Increase () B Decrease(¯) Decrease(¯) Decrease(¯) C Increase () Decrease(¯) Decrease(¯) D Decrease(¯) Increase () Decrease(¯) E Decrease(¯) Decrease(¯) Increase ()

A.

A
B.

B
C.

C
D.

D
E.

E

Correct Answer
B. B

Explanation
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.

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6.

Polyuria, polydipsia, weakness, and fatigue are characteristic of several endocrine disorders. In one patient, the physician notes both peripheral neuropathy and visual changes as well. What clinical condition would be most likely to produce these six findings?

A.

Addison’s disease
B.

Conn’s syndrome
C.

Cushing’s syndrome
D.

Diabetes mellitus
E.

Diabetes insipidus

Correct Answer
D. Diabetes mellitus

Explanation
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.

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7.

What branch of the autonomic nervous system elicits catecholamine release from the adrenal medulla and what is the neurotransmitter and receptor responsible for increased epinephrine release from adrenal medullary chromaffin cells? Branch of ANS Neurotransmitter Receptor A Parasympathetic Norepinephrine Alpha-1 B Sympathetic Norepinephrine Alpha-1 C Sympathetic Acetylcholine Muscarinic D Parasympathetic Acetylcholine Muscarinic E Sympathetic Acetylcholine Nicotinic

A.

A
B.

B
C.

C
D.

D
E.

E

Correct Answer
E. E

Explanation
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.

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8.

In the synthesis of adrenal medullary hormones, cortisol stimulates the conversion of

A.

Tyrosine to dopa.
B.

Tyrosine to dopamine
C.

Dopamine to dopa
D.

Epinephrine to norepinephrine
E.

Norepinephrine to epinephrine

Correct Answer
E. Norepinephrine to epinephrine

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

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9.

In situations of stress and anxiety, epinephrine synthesis can be increased when cortisol stimulates the enzyme

A.

Tyrosine hydroxylase
B.

Amino acid decarboxylase
C.

COMT (catecholamine methyl transferase)
D.

MAO (monoamine oxidase)
E.

PNMT (phenylethanolamine-N-methyl transferase)

Correct Answer
E. PNMT (phenylethanolamine-N-methyl transferase)

Explanation
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.

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10.

Which hormone is produced by the zona reticularis ?

A.

LH
B.

Androstenedione
C.

Melatonin
D.

Aldosterone
E.

Cortisol
F.

Angiotensin II

Correct Answer
B. Androstenedione

Explanation
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.

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