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HRM Test 1 > Adrenal Cortex Phys- Trachte > Flashcards

Adrenal Cortex Phys- Trachte Flashcards

1
Q

What are the three zones of the adrenal cortex?

A

Zona Glomerulosa
Zona Fasiculata
Zone Reticularis

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2
Q

Which zone of the adrenal cortex secretes aldosterone?

A

Zona glomerulosa

Aldosterone = mineralcorticoid

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3
Q

Which zone makes cortisol (glucocorticoid)

A

Zone fasiculata

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4
Q

Which zone makes sex hormones (androgens)?

A

Zone Reticularis

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5
Q

Describe the glucocortiocoid endocrine axis

A

Hypothalamus secretes CRH

Anterior pituitary secretes ACTH

Adrenal cortex secretes cortisol

Cortisol acts on immune system, liver, muscle, and adipose tissue

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6
Q

What kind of receptor does CRH bind on corticotrophs in anterior pituitary?

A 
Gs-protein coupled receptor
Stimulates adenylate cyclase
Increases cAMP
Increased synthesis of POMC
POMC is cleaved to produce:
MSH
ACTH
Liptropin
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7
Q

What 3 things are proudced during cleavage of POMC in corticotrophs of the anterior pituitary?

A

ACTH
MSH
Lipotropin

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8
Q

What does MSH do?

A

Stimulates melanocyte proliferation and pigmentation

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9
Q

What receptor does ACTH bind?

A

Melanocortin-2-receptor in adrenal cortical cells

Gs coupled receptor
Elevates cAMP
Starts signal transduction cascade involving PKA

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10
Q

What cancer usually causes ectopic production of ACTH?

A

Small Cell lung cancer

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11
Q

What is the rate-limiting step in adrenal steroid synthesis?

A

Production of “side chain cleavage enzyme” in the adrenal cortex

*This enzyme is required for cholesterol conversion to pregnenolone

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12
Q

What enzyme is required for cholesterol conversion to pregnenolone?

A

Side-chain cleavage enzyme (CYP11A = P450scc)

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13
Q

Where would you find glucocorticoid receptors? What is the sequence of events?

A

Cytosol! Belong to the nuclear receptor super family

Hormone bound receptor moves to nucleus and forms homodimers

Homodimers act as transcription factors - bind to Glucocorticoid Response elements

Initiate OR inhibit transcription

Regulates development, metabolism, and immune repsonse

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14
Q

The mineral corticoid receptor has equal affinity for aldosterone and cortisol…. cortisol is much more abundant than aldosterone…… how does aldosterone responsive tissue prevent cortisol from binding to the MR?

A

In aldosterone-responsive cells cortisol is enzymatically converted to cortisone = a metabolically inactive steroid so has no affect (and can’t bind receptor)

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15
Q

What is the primary active glucocorticoid?

A

Cortisol!

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16
Q

What is 90% of cortisol bound to in circulation?

A

60% = CBG = corticotropin binding globulin = transcortin

30% = albumin

17
Q

What happens to bone at sustained elevation of glucorticoids?

A

Decreased osteoblast activity - decreased bone mass - osteoporosis

18
Q

What is Cushing Syndrome?

A

Excessive secretion of cortisol

May be due to a variety of causes

19
Q

If Cushing syndrome is due to excess ACTH secretion (thus increased cortisol) what is normally the cause?

A

Pituitary Adenoma

20
Q

Why do you see hyperpigmentation in pituitary adenomas?

A

Increased POMC!! Remember it produces ACTH, Lipotropin, and MELANOCYTE-STIMULATING HORMONE!

Those melanocytes are working like craaaaaazy!

21
Q

If Cushing syndrome is due to primary glandular excess production of cortisol (like an adrenal tumor) what would the blood profile look like?

A

Increased cortisol

BUT DECREASED ACTH (from negative feedback)

22
Q

What would the blood profile look like in a pituitary adenoma?

A 
Increased ACTH (due to the adenoma)
Increased Cortisol
Low CRH (negative feedback)
23
Q

Effect on CRH, ACTH, and cortisol:

Hypothalamic damage resulting in no CRH secretion

A
  • Low CRH
  • Low ACTH
  • Low Cortisol
24
Q

Effect on CRH, ACTH, and cortisol:

Pituitary damage resulting in no ACTH secretion

A
  • Low ACTH
  • Low Cortisol
  • High CRH
25
Q

Effect on CRH, ACTH, and cortisol:

Adrenal damage resulting in no cortisol secretion (Addison’s disease)

A
  • Low cortisol
  • High CRH
  • High ACTH
26
Q

Effect on CRH, ACTH, and cortisol:

Receptor damage resulting in no efficacy of cortisol

A
  • High cortisol
  • High ACTH
  • High CRH
27
Q

Effect on CRH, ACTH, and cortisol:

Tumor secreting excess CRH

A
  • High CRH
  • High ACTH
  • High Cortisol
28
Q

Effect on CRH, ACTH, and cortisol:

Tumor secreting excess ACTH (Cushing’s)

A
  • High ACTH
  • High Cortisol
  • Low CRH
29
Q

Effect on CRH, ACTH, and cortisol:

Tumor secreting excess cortisol

A
  • High Cortisol
  • Low ACTH
  • Low CRH
30
Q

What 3 enzymes can causes congenital adrenal hyperplasia?

A

17 a-hydroxylase
21-hydroxylase
11B-hydroxylase

31
Q

What causes congenital adrenal hyperplasia?

A

Adrenal enzyme deficiency characterized by enlargement of both adrenal glands due to increased ACTH stimulation (due to decreased cortisol production)

32
Q

What are all steroids made from?

A

Cholesterol!

33
Q

What is Addison’s disease?

A

Immune mediated destruction of adrenal cortex

decreased production of cortisol and aldosterone

Compensatory increase in POMC (increased ACTH and MSH)

Thus you get hyperpigmentation!

34
Q

Does aldosterone exhibited negative feedback on ACTH secretion?

A

NO!!!!!!

HRM Test 1 (11 decks)

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