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Endocrinology > Physiology of Adrenal Cortex > Flashcards

Physiology of Adrenal Cortex Flashcards

1
Q

What are the zones of adrenal cortex?

A

Zona glomerulosa, fasciculata, reticularis

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2
Q

Major function of aldosterone

A

Increase Na absorption and K secretion to maintain fluid volume

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3
Q

Major function of glucocorticoids

A

provide sustained energy source. Enhance gluconeogenesis in liver, increase fatty acids, raise blood glucose level

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4
Q

Major function of catecholamines

A

rapid response to stress; fuel availability to increase CV function and performance

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5
Q

Major function of adrenal sex hormones

A

growth, developmental control in men and women

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6
Q

Describe globulin role in steroid binding.

A

High affinity reversible binding. Cs-binding globulin (CBP), aldosterone binding globuline, sex-steroid binding, progesterone binding

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7
Q

Describe the role of albumin in steroid binding

A

low affinity reversible binding

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8
Q

Describe the binding of cortisol

A

90% is bound to transcortin(majority) and albumin (minority), 10% is free, half life is 60 -90 minutes

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9
Q

Describe the binding of albumin

A

60% bound to transcortin, aldosterone binding globulin and albumin, 40% is free, half life is 20 minutes

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10
Q

What are the purposes of hormone protein binding?

A

Suppresses the biological activity of steroid hormones. Protect the hormone from structural alterations. Extend the half life time of hormones in the plasma. Provide an active hormone to the target tissue rapidly when needed.

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11
Q

___ is the source for synthesis of all steroids.

A

Cholesterol

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12
Q

What is the main cholesterol provider?

A

LDL.

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13
Q

_____ cholesterol is synthesized in the adrenal gland.

A

20%

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14
Q

Where are LDL receptors located in adrenal cortical cells?

A

plasma membrane

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15
Q

How is LDL transported into cells?

A

endocytosis. Internalization of LDL receptors within clathrin coated pits. Formation of endosomes and lysosomes. Cholesterol is released from receptors. LDL receptors are recycled.

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16
Q

How is cholesterol stored in adrenal cells?

A

cholesterol is esterified and stored in cytoplasmic vesicles until it is needed for the synthesis of corticosteroid hormone.

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17
Q

What is the mitochondrial rate limiting step in adrenal corticosteroid synthesis?

A

Cholesterol–> pregnenolone.

Key enzyme is CYP11A1.

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18
Q

How does neuroendocrine control steroidogenesis?

A

ACTH! stimulates CYP11A1, increase cholesterol uptake

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19
Q

What makes up 90% of all mineralcorticoid activity? Which is most potent

A

Aldosterone!

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20
Q

T or F Deoxycorticosteone is a glucocorticoid.

A

F–> mineralcorticoid

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21
Q

Describe the potency of deoxycorticosterone vs aldosterone

A

1/30

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22
Q

What is a synthetic potent aldosterone analogue that is slightly more potent than aldosterone?

A

9a-Fluorocortisol

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23
Q

What is the final step of aldosterone synthesis? What upregulates the enzyme?

A

corticosterone–> aldosterone

Enzyme is aldosterone synthase. Upregulated by Ang II

24
Q

Mineralcorticoid synthesis occurs in the _____.

A

z. glomerulosa

25
Q

Where are mineralcorticoid receptors found?

A

Kidneys, brain, lungs, heart, vascular tissues

26
Q

Ligand binding properties of MRs

A

High receptor affinity for aldosterone. Non-specific activation by glucocorticoids. Cortisol: high affinity- high blood level- active ligand?
Cortisone- low receptor affinity, inactive ligand

27
Q

Mineralcorticoid MOA for gene expression

A
  1. Aldosterone binds MR
  2. Translocated to nucleus
  3. Binding to promotor area of specific genes
  4. upregulation of gene expression of things like Na/K ATPase
28
Q

What are the non-genomic effects of mineralcorticoids

A

via protein phosphorylation mediated cell signaling pathways

29
Q

What glucocorticoids have mineralcorticoid activity?

A

corticosterone, cortisol, cortisone

30
Q

What does 11B hydroxysteroid dehydrogenase do?

A

cortisol to cortisone

31
Q

What 4 channels are regulated by aldosterone?

A

NaK ATPase, ENaC, Sgk1, ROMK

32
Q

Sgk1 activates ____ to maintain _____.

A

Na/K ATPase, ENac, and ROMK; low intra Na and high intra K

33
Q

Renal affects of mc on H

A

secretion; metabolic alkalosis; increase carbonic anhydrase

34
Q

Renal affects of mc on HCO3

A

production; metabolic alkalosis; increase carbonic anhydrase

35
Q

___ is the most potent GC and has __% of total gc activity

A

cortisol; 90%

36
Q

Potency and percent gc activity of corticosterone

A

modest; 4%

37
Q

What is the last step in cortisol synthesis?

A

11B- hydroxylase

38
Q

Where to gc bind receptors?

A

cytoplasm

39
Q

Genomic effects of GC

A

hormone receptor complex goes to nucleus, binds promoter regions, stimulates/repress gene expression, suppression via factors like NFkB

40
Q

T or F the liver stimulates protein catabolism.

A

Falso. Other various organs but not liver.

41
Q

What does GC do in adipose tissue?

A

promote lipolysis and enhance mobilization and oxidation of FA as an alternative energy source in starvation. Increase food uptake

42
Q

High doses of oral cortisol can lead to ____.

A

Cushings. deposition of fat in chest and head, fat lump between shoulders, high BP, diabetes and bone loss

43
Q

What cells are the main targets of cortisol in regard to immunity/inflammation

A

macs and t cell lymphocytes

44
Q

What does GC do to collagen synthesis in the skin

A

decrease

45
Q

What does GC do to Ca absoprtion in intestine? Kidney? blood? growth?

A

decrease all

46
Q

Effect of GC on blood vessels

A

vasoconstriction, promote HTN, reduce blood clotting

47
Q

Effect of GC on GI

A

stimulate GI function

48
Q

Effect of GC on nervous system

A

suppress hypo-pit axis; increase appetite

49
Q

What are the androgen precursors and androgens?

A

DHEA, androstenedione, testosterone

50
Q

Effects of androgens on males and females

A

Males: weak
females: masculinization, adrenogenital syndrome

51
Q

What are the female sex hormones?

A

progesterone and estrogens

52
Q

What does adrenal medulla synthesize?

A

Epinephrine (80%), norepinephrine (20%)

53
Q

Structure of hormones released by adrenal medulla

A

amino acid derivatives

54
Q

Half life of hormones secreted by adrenal medulla

A

short, 2 min

55
Q

What are the targets and functions of hormone secreted by adrenal medulla

A

heart, lungs, muscles, vessels, Immediate response to stress; Neural control

56
Q

What are the effects of severe stress on hypothalamic pit. adrenal axis?

A

enlargement and hyperfunction leading to major health problems- heart disease, immunosuppression, digestive problems, sleep disorders, anxiety, depression

Endocrinology (31 decks)

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