The Adrenal Gland Flashcards

1
Q

How much do the adrenal glands weight?

A

4g each

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2
Q

Where does the left adrenal gland drain?

A

Into the left renal vein or left inferior phrenic vein

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3
Q

Where does the right adrenal gland drain?

A

Into the IVC

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4
Q

Proportionally, how much of the adrenal glands is medulla and how much is cortex?

A

Cortex - 75%

Medulla - 25%

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5
Q

The adrenal medulla secretes what?

A

Catecholamines:
Epinephrine
Norepinephrine
Dopamine

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6
Q

The adrenal medulla is derived from what?

A

Modified sympathetic ganglion derived from neural crest tissue

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7
Q

The adrenal cortex is derived from what?

A

Mesoderm

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8
Q

The adrenal cortex secretes what?

A

Mineralocorticoids
Glucocorticoids
Sex steroids

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9
Q

What is the role of mineralocorticoids? Give an example

A

Aldosterone

Regulation of Na+ and K+

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10
Q

What is the role of glucoocorticoids? Give an example

A

Cortisol

Regulation of plasma glucose

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11
Q

What is the arrangement of the adrenal cortex?

A

3 layers:
Zona glomerulosa
Zona fasciculata
Zona reticularis

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12
Q

Steroid hormones are derived from what?

A

Cholesterol

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13
Q

What is DHEA?

A

Pre-hormone of testosterone and estrogen

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14
Q

What are the main products of the adrenal cortex?

A

Cortisol

Aldosterone

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15
Q

How does DHEA change in life?

A

Declines with age

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16
Q

What is the common cause of congenital adrenal hyperplasia?

A

Defects in 21-hydroxylase

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17
Q

What do defects in 21-hydroxylase cause?

A

Deficiency in aldosterone and cortisol
Disruption of salt and glucose
Accumulation of steroid precursors

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18
Q

Accumulation of steroid precursors causes what?

A

Excessive adrenal androgen production

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19
Q

Cortisol causes feedback inhibition on which hormones?

A

CRH

ACTH

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20
Q

Hypothalamic secretion of CRH stimulates what?

A

ACTH release from the anterior pituitary

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21
Q

Anterior pituitary ACTH secretion stimulates what?

A

Cortisol secretion from the adrenal cortex

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22
Q

21-hydroxylase is necessary for what?

A

Conversion of progesterone to Cortisol and Aldosterone

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23
Q

Why does 21-hydroxylase cause adrenal hyperplasia?

A
  1. Inhibited cortisol synthesis
  2. Loss of -ve feedback on ACTH and CRH
  3. Increased ACTH secretion
  4. Enlargement of adrenal glands
  5. (CRH synthesis remains)
  6. Huge excess of sex steroids
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24
Q

What is the negative feedback effect of ACTH?

A

Inhibition of CRH synthesis

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25
Q

What type of hormone is cortisol?

A

Glucocorticoid hormone

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26
Q

All nucleated cells have what receptors?

A

Cytoplasmic glucocorticoid receptors

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27
Q

What % of plasma cortisol is bound? What is it bound to?

A

95%

Cortisol binding globulin

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28
Q

How does cortisol alter gene expression?

A

Hormone receptor complex migrates to nucleus

Binds to DNA via hormone-response element

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29
Q

What is the pattern of cortisol release?

A

Circadian rhythm
Preceded by ACTH release
Cortisol burst longer (longer 1/2 life)

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30
Q

When does cortisol peak?

A

6-9am

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31
Q

When is cortisol lowest?

A

Midnight

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32
Q

Fluctuations of cortisol levels are related to what?

A

Stress

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33
Q

What is the permissive effect of cortisol?

A

Permissive effect on glucagon
Makes glucagon able to respond to a hypoglycaemic challenge
Permissive effect on epinephrine alpha receptors causing vasoconstriction - hypertension

34
Q

Removing adrenal glands has what effect on animals?

A

Makes them incapable of maintaining extracellular fluid volume

35
Q

What is the role of aromatase?

A

Converts Testosterone to Estradiol

36
Q

21-hydroxylase converts progesterone into what?

A

Corticosterone

37
Q

Corticosterone is converted into what?

A

Aldosterone

38
Q

How does 21-hydroxylase deficiency cause deformities?

A

Malformed genitals due - ambiguous sex

39
Q

Why does a 21-hydroxylase deficiency cause a massive increase in ACTH but not CRH?

A

Because the increase of ACTH also inhibits CRH which is being conversely NOT inhibited by the lack of cortisol

40
Q

What are the glucocorticoid actions of cortisol?

A

Gluconeogenesis
Proteolysis
Lipolysis
Decreased insulin sensitivity

41
Q

Cortisol decreases the insulin sensitivity of what?

A

Muscles and adipose tissue

42
Q

How does cortisol effect gluconeogenesis?

A

Cortisol stimulates formation of gluconeogenic enzymes in the liver
Increasing gluconeogenesis

43
Q

How does cortisol effect proteolysis?

A

Increased proteolysis of muscle protein to provide gluconeogenic substrates in the liver

44
Q

How does cortisol effect lipolysis?

A

Stimulates lipolysis which increases plasma [FFA]

45
Q

What is the benefit of cortisol stimulating lipolysis?

A

Creates an alternative fuel supply whilst glycerol is created for gluconeogenesis

46
Q

What are the non-glucocorticoid effects of cortisol?

A

Reduces Ca2+ balance
Impairs mood and cognition
Permissive effects on norepinephrine
Suprresses the immune system

47
Q

How does Cortisol effect Ca2+?

A

Decreases absorption
Increases kidney excretion
Increases bone resorption
Net Ca2+ loss

48
Q

Impaired mood and cognition is strongly associated with which hormone excess?

A

Hypercortisolaemia

49
Q

Hypertension is strongly associated with which hormone excess?

A

Hypercortisolaemia (Cushing’s Disease)

50
Q

Permissive effects of cortisol on norepinephrine have what effects?

A

Hypertension

Vasoconstrictive effect on vascular smooth muscle (alpha receptors)

51
Q

How does Cortisol effect the immune system?

A

Suppression
Reduced lymphocyte count
Inhibited inflammatory response

52
Q

What is the side effect of glucocorticoid therapy on the immune system?

A

Suppressed immune system

Increased severity and frequency of infection

53
Q

What is the side effect of glucocorticoid therapy on muscle?

A

Increased protein catabolism

54
Q

What is the side effect of glucocorticoid therapy on adipose tissue?

A

Lipolysis

55
Q

Aldosterone is what type of hormone?

A

Mineralocorticoid

56
Q

Aldosterone acts on what?

A

Distal tubule of kidney

Determines levels of mineral in/out

57
Q

What is the effect of aldosterone on ions?

A

Increased Na+ resorption

Increased K+ excretion

58
Q

How is aldosterone controlled?

A

Renin-angiotensin-aldosterone system

59
Q

Increased aldosterone has what effect?

A

Stimulation of Na+ and water retention
K+ depletion
Increased blood pressure/volume

60
Q

Decreased aldosterone has what effect?

A

Na+ and Water loss
Increased plasma [K+]
Decreased blood pressure

61
Q

What is Cushing’s disease?

A

Hypersecretion of cortisol

62
Q

What is the typical cause of iatrogenic hypersecretion of cortisol?

A

Overdose of therapeutic cortisol

63
Q

Hypersecretion of cortisol is typically due to tumours where? Which is most common?

A

Adrenal cortex

PITUITARY GLAND

64
Q

What is Addison’s disease?

A

Hyposecretion of all adrenal steroid hormones

65
Q

What is the cause of Addison’s disease?

A

Autoimmune destruction of the adrenal cortex

66
Q

What is the common physical presentation of Cushing’s?

A

Increased fat deposits in neck, face, trunk
“Moon face”
Wasting in extremities

67
Q

CRH and ACTH release is PROMOTED by what?

A

Stress

68
Q

What daily factors disinhibit the HPA axis?

A

Alcohol
Caffeine
Lack of sleep

69
Q

What is the general role of the adrenal medulla?

A

Neuroendocrine

70
Q

Preganglionic sympathetic fibres terminate where in the adrenal medulla?

A

Specialised postganglionic cells in the adrenal medulla

71
Q

What is the effect of neural stimulation of Specialised postganglionic cells in the adrenal medulla?

A

Release of neurohormones directly into the blood

Adrenaline

72
Q

What is pheochromocytoma?

A

Neuroendocrine tumour of the adrenal medulla

73
Q

Pheochromocytoma causes what?

A

Excess catecholamines

74
Q

Pheochromocytoma presents how?

A

Excess catecholamines:
↑HR - ↑CO - ↑BP
Diabetogenic

75
Q

What is tertiary hypercortisolaemia?

A

Hypercortisolaemia due to pathology of the hypothalamus

76
Q

What is Secondary hypercortisolaemia?

A

Hypercortisolaemia due to pathology of the pituitary gland

77
Q

What is Primary hypercortisolaemia?

A

Hypercortisolaemia due to pathology of the adrenal cortex

78
Q

What must always be remembered when withdrawing glucocorticoids?

A

Adrenal insufficiency

79
Q

How do you take a patient off glucocorticoids?

A

Slowly/weaning

80
Q

How does fast withdrawal of glucocorticoid Rx cause adrenal insufficiency?

A

Loss of trophic effect of ACTH on adrenal gland causes atrophy
Insufficiency
WORSENED because therapeutic cortisol enhances the -ve feedback effect on ACTH and CRH