Question 1

Which embryological origin is responsible for the development of the adrenal medulla?

Accepted Answer

Neural crest cells (ectoderm)

Question 2

What is the primary function of chromaffin cells in the adrenal medulla?

Accepted Answer

Secretion of catecholamines such as epinephrine and norepinephrine

Question 3

Which enzyme, regulated by glucocorticoids, is responsible for converting norepinephrine to epinephrine in the adrenal medulla?

Accepted Answer

Phenylethanolamine N-methyltransferase (PNMT)

Question 4

A patient presents with treatment-resistant hypertension, headache, and palpitations. Laboratory tests reveal high plasma catecholamines. What is the most likely diagnosis?

Accepted Answer

Pheochromocytoma

Question 5

Which of the following statements about the adrenal cortex and medulla is correct?

Accepted Answer

The cortex develops from mesoderm, while the medulla develops from neural crest cells

Question 6

Which of the following best describes the effect of epinephrine compared to norepinephrine on cardiac output?

Accepted Answer

Epinephrine has a greater effect than norepinephrine

Question 7

What is the correct sequence for catecholamine biosynthesis starting from tyrosine?

Accepted Answer

Tyrosine → Dopa → Dopamine → Norepinephrine → Epinephrine

Question 8

Which receptor subtype is primarily responsible for the peripheral effects of catecholamines?

Accepted Answer

Adrenergic receptors (α and β)

Question 9

In mammals, what percentage of released catecholamines from the adrenal medulla is epinephrine?

Accepted Answer

80%

Question 10

Which of the following is a plausible reason for using phenoxybenzamine before surgical resection of a pheochromocytoma?

Accepted Answer

To irreversibly block alpha adrenoceptors and prevent hypertensive crisis

Question 11

Which cell type is most numerous in the adrenal medulla and stores epinephrine?

Accepted Answer

Epinephrine-storing chromaffin cells

Question 12

Which of the following tissues is NOT a location where chromaffin cells are found?

Accepted Answer

Pancreas

Question 13

In species where chromaffin cells are independent of adrenal steroidogenic cells, which catecholamine is produced?

Accepted Answer

Only norepinephrine

Question 14

Which of the following is a classic triad of symptoms for pheochromocytoma?

Accepted Answer

Hypertension, headache, sweating

Question 15

Which of the following best explains why the adrenal medulla is considered a modified sympathetic ganglion?

Accepted Answer

It contains axonless secretory cells derived from neural crest

Question 16

Which of the following equations correctly represents the conversion of norepinephrine to epinephrine?

Accepted Answer

$$	ext{Norepinephrine} + 	ext{PNMT} ightarrow 	ext{Epinephrine}$$

Question 17

Which of the following best describes the effect of glucocorticoids on catecholamine synthesis in the adrenal medulla?

Accepted Answer

They stimulate the expression of PNMT, increasing epinephrine production

Question 18

Which of the following is a plausible explanation for increased metabolic rate in patients with pheochromocytoma?

Accepted Answer

Excessive secretion of epinephrine stimulates beta adrenergic receptors

Question 19

Which of the following best describes the relationship between the adrenal cortex and medulla in mammals?

Accepted Answer

The cortex regulates medullary epinephrine production via glucocorticoids

Question 20

Which of the following is a plausible reason for the dominance of epinephrine-storing chromaffin cells in the mammalian adrenal medulla?

Accepted Answer

Glucocorticoids from the cortex induce PNMT expression, favoring epinephrine synthesis

Adrenal Medulla: Structure, Development, and Function

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