Adrenal Gland: Histology and Physiology Flashcards

1
Q

In the image below, where is the adrenal medulla?

A

C

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2
Q

In the image below, in which regions are the stem cells of the adrenal cortex located?

A. 1

B. 2

C. 3

D. 4

E. 5

A

B. 2

Clinical correlation: Excess exogenous steroid administration (e.g., given as an anti- inflammatory agent) abolishes ACTH secretion and the adrenal gland atrophies. As one gradually tapers off the hydrocortisone (cortisol) given to a patient, the ACTH level gradually is restored and the tissue layers are restored as well. Consequences of suddenly stopping exogenous glucocorticoid use are therefore dire as these layers need time to regenerate at the end stage of steroid therapy. See: pathology and pharmacology.

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3
Q

Which of the following regions typically has the highest average rate of steroid secretion per day?

A. 1

B. 2

C. 3

D. 4

E. 5

A

D. 4

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4
Q

What class of hormone is secreted from the darker cells in the image below?

A. Mineralocorticoid

B. Glucocorticoid

C. Androgen

D. Catecholamine

A

C. Androgen

The zona glomerulosa (ZG) secretes mineralocorticoids – aldosterone

ZF The zona fasciculata (ZF) secretes glucocorticoids – cortisol

ZR The zona reticularis (ZR) secretes sex steroids – androgens, mainly

Medulla – dehydroepiandrosterone (DHEA)

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5
Q

In which region of the adrenal gland is one most likely to find sinusoids?

A. Zona glomerulosa

B. Zona fasciculata

C. Zona reticularis

D. Adrenal medulla

A

B. Zona fasciculata

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6
Q

Which of the following directly increase aldosterone secretion?

A. Plasma potassium

B. Angiotensin II

C. ACTH

D. Cortisol

E. Hypotension

A

A. Plasma potassium

B. Angiotensin II

C. ACTH

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7
Q

Through what cellular mechanism of action does aldosterone produce effects in its target cells?

A. Increases adenylyl cyclase (AC) activity in the target cells

B. Increases phospholipase C (PLC) activity in the target cells

C. Activates tyrosine kinases in the target cells

D. Activates the JAK-STAT second messenger system in the target cells

E. Increases transcription of selected proteins in the target cells

A

E. Increases transcription of selected proteins in the target cells

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8
Q

For which of the following adrenal hormones is circadian modulation of its secretion most likely?

A. Aldosterone

B. Cortisol

C. DHEA

D. Epinephrine

A

B. Cortisol

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9
Q

Within the hypothalamo-pituitary-adrenal axis, what hormone is the controlled variable for negative feedback and where does it exert this feedback in the hypothalamus?

A. Aldosterone, in the paraventricular nucleus

B. Aldosterone, in the arcuate nucleus

C. Aldosterone, in the supraoptic nucleus

D. Cortisol, in the paraventricular nucleus

E. Cortisol, in the arcuate nucleus

F. Cortisol, in the supraoptic nucleus

A

D. Cortisol, in the paraventricular nucleus

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10
Q

Which of the following is/are permissive effects of cortisol?

A. Inhibition of gene expression for prolactin

B. Conversion of proteins into glucose

C. Enhancement of glucagon secretion

D. Increased water retention by the kidneys

E. Decreased prostaglandin synthesis

A

A. Inhibition of gene expression for several pituitary hormones e.g. prolactin, POMC (pre- ACTH), and ADH

B. Conversion of proteins into glucose: effect on glucagin and epinephrine; increase blood glucose via gluconeogenesis

Regulates levels of insulin- sensitive GLUT-4 proteins, which then alters ability to respond to insulin in skeletal muscle and adipose tissue

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11
Q

What is the most important function of DHEA?

A. Increases gluconeogenesis in liver cells

B. Substrate for androgen and estrogen production (especially in females)

C. Increased water retention by the kidneys

D. Negative feedback on its own production

E. Fetal development of reproductive structures (especially in males)

A

B. Substrate for androgen and estrogen production (especially in females)

DHEA does not have a specific binding protein but unlike aldosterone it also has very few target tissues, and physiologically it serves as a backup source of precursors to synthesis of more potent androgens and estrogens by the gonads, which does not need them. DHEA-S has been known for decades to affect GABA neuron function in the brain but because this will never be on the USMLE, it is more important to think of it as a reserve for those precursors of more potent androgens and estrogens.

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12
Q

Which of the following effects is/are mediated by epinephrine?

A. Increase plasma glucose

B. Increase heart rate

C. Increase intestinal secretions

D. Increase metabolic rate

E. Increase blood flow to skeletal muscle

F. Increase blood flow to skin

A

A. Increase plasma glucose

B. Increase heart rate/CV function

D. Increase metabolic rate

E. Increase blood flow to skeletal muscle

Decrease GI function

Catecholamines (dopamine, norephinephrine, epinephrine) are made in adrenal medulla → ↑ SNS effects

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13
Q

In an acute response to stress, which of the following are effects of both cortisol and epinephrine?

A. Increased hepatic glycogenolysis

B. Increased hepatic gluconeogenesis

C. Increased adipose tissue lipolysis

D. Increased oxygen delivery to tissues

E. Increased secretion of growth hormone

A

A. Increased hepatic glycogenolysis

B. Increased hepatic gluconeogenesis

C. Increased adipose tissue lipolysis

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14
Q

A fourteen-year-old girl presents to her family doctor with a chief complaint of visual impairment. Follow-up tests establish that she has a non-hormone secreting pituitary adenoma, which has other consequences including low blood pressure and nearly undetectable levels of cortisol in her plasma. What type of adrenal dysfunction is described in this vignette?

A. Primary adrenal hyperfunction

B. Secondary adrenal hyperfunction

C. Primary adrenal hypofunction

D. Secondary adrenal hypofunction

A

C. Primary adrenal hypofunction

• Primary: Addison’s Disease, aka Primary adrenal insufficiency.

• Adrenal Tissue does not respond to ACTH

– Low production of aldosterone and cortisol

– Little to no feedback of ACTH secretion
– ACTH levels in plasma are far above normal

• Secondary: Secondary adrenal insufficiency
– Little production of ACTH → no negative feedback
– Without ACTH, adrenal gland produces little aldosterone and cortisol
– ACTH levels will be low but if measurable in the lab, CRH levels would be high

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15
Q

In the patient above, what effect on her skin color would be most likely as another consequence from this condition?

A. Less pigmented than before this occurred.

B. Unchanged pigmentation compared to before this occurred.

C. More pigmented than before this occurred.

A

A. Less pigmented than before this occurred

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16
Q

Review of Mineralocorticoids

A

→ Prototype: Aldosterone

→Produced in Zona Glomerulosa

→Needs 21-Hydroxylase (ZG/ZF), and Aldosterone synthase, (ZG only)

Function: Increase salt and water retention, mostly through renal action

17
Q

Review of Glucocorticoids

A

→Prototype: Cortisol (aka Hydrocortisone)

→Produced in Zona Fasciculata (minor production from ZG)

→Needs 21-Hydroxylase (ZG/ZF), and 17 alpha hydroxylase, (ZF/ZR)

Function: Many, e.g., increase energy mobilization from all sources including proteins, and anti-inflammatory effects

18
Q

Review of Adrenal Androgens

A

→Prototypes: DHEA, Androstenedione

→Produced in Zona Reticularis

→Needs 17-alpha hydroxylase (ZF/ZR) and 17,20 lyase, (ZR only)

Function: Weak Androgenic Effects, precursor to gonadal androgens and estrogens

19
Q

Chronic response to stress

A

Integrated Response to Chronically Elevated Cortisol (e.g., in Cushings Syndrome)