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Endocrinology > Adrenal glands > Flashcards

Adrenal glands Flashcards

1
Q

Where are the adrenal glands located?

A

Above the kidneys

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2
Q

How many layers are the adrenal glands divided up into?

A

Three

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3
Q

What are the three layers of the adrenal glands? Which is the outer, middle and inner layer?

A

Capsule - outer

Cortex - middle

Medulla - inner

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4
Q

What is the capsule made up of?

A

Fibrous connective tissue

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5
Q

How many layers is the adrenal cortex divided up into?

A

Three

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6
Q

What are the three layers of the adrenal cortex? Which is the outer, middle and inner layer?

A

Zona glomerulosa - outer

Zona fasciculata - middle

Zona reticularis - inner

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7
Q

What is the adrenal medulla made up of?

A

Chromaffin cells

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8
Q

What are steroid hormones synthesised from?

A

Cholesterol

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9
Q

Where are steroid hormones synthsised?

A

In adrenal glands

In gonads

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10
Q

How do steroid hormones react to water?

A

Hydrophobic

Insoluble in water

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11
Q

Where are steroid receptors located?

A

Intracellular

Nuclear receptors

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12
Q

What do ligand-bound steroid receptors do?

A

Modulate gene transcription

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13
Q

What are some examples of the different types of steroid hormones?

A 
Glucocorticoids
Mineralocorticoids
Androgens
Oestrogens
Progestins
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14
Q

Glucocorticoids, mineralocorticoids and androgens are all types of …?

A

Corticosteroid hormones

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15
Q

What is the role of the adrenal cortex?

A

Synthesise corticosteroid hormones

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16
Q

What are corticosteroid hormones?

A

Steroid hormones synthesised in the adrenal cortex

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17
Q

What does the zona glomerulosa synthesise?

A

Mineralocorticoids - mainly aldosterone

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18
Q

What does the zona fasciculata synthesise?

A

Glucocorticoids - mainly cortisol

but also corticosterone, cortisone

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19
Q

What does the zona reticularis synthesise?

A

Androgens - DHEA, androstenedione

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20
Q

What can the androgens - DHEA, androstenedione - be converted into?

A

Oestrogen

Testosterone

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21
Q

How do corticosteroids enter cells?

A

Readily diffuse across plasma mmebrane

enter cell

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22
Q

What do corticosteroid hormones bind to once they enter cells?

A

Corticosteroid receptors

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23
Q

How do corticosteroid receptors normally exist within a cell?

A

In the cytoplasm

Bound to chaperone proteins e.g. hsp90

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24
Q

What does corticosteroid binding to a corticosteroid receptor result in?

A

Dissociation of chaperone proteins e.g. hsp90

Translocation of the corticosteroid hormone-receptor complex to the nucleus

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25
Q

What does the corticosteroid hormone-receptor complex do in the nucleus?

A

Binds to corticosteroid response elements (CREs)

Or transcription factors

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26
Q

What are corticosteroid-response-elements?

A

DNA sequences
In promoter sequences of genes
That are regulated by corticosteroids

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27
Q

What does the corticosteroid hormone-receptor complex binding to CREs and transcription factors result in?

A

Activates gene expression

Certain proteins produced

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28
Q

Why are steroid hormone responses delayed compared to e.g. adrenaline?

A

Because steroid hormone effects are brought about by newly synthesised proteins
Takes a while to produce them

Whereas other hormones act on already existing proteins in the cell

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29
Q

Why does aldosterone not dissolve in the blood?

A

Because it’s hydrophobic

insoluble in water

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30
Q

How is aldosterone carried in the blood?

A

Mainly by serum albumin

Lesser extent by transcortin

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31
Q

Where does aldosterone have its main effect?

A

Distal tubules of nephron

Collecting ducts of nephron

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32
Q

What effect does aldosterone have in the nephron?

A

Increases expression of Na+ K+ pump
gives reabsorption of Na+
excretion of K+

33
Q

What do the actions of the Na+ K+ pump lead to?

A

Increased retention of water
increased blood volume
increased blood pressure

34
Q

Aldosterone is part of what system?

A

RAAS

35
Q

How is cortisol carried in the blood?

A

Transcortin

36
Q

What is transcortin?

A

Carrier protein

37
Q

What type of metabolic effects does cortisol have?

A

Catabolic effects

38
Q

What catabolic affects does cortisol have?

A

Increased proteolysis in muscle

Increased lipolysis in adipose tissue

Increased gluconeogenesis in liver

39
Q

What does increased gluconeogenesis in the liver lead to? How?

A

Increased glycogenesis

Because increased glucose
Increased insulin
Increases glycogenesis

40
Q

How do glucocorticoids cause increased proteolysis in muscle?

A

Decreased sensitivity to insulin - less stimulation of protein synthesis
Decreased glucose uptake - less protein synthesis

Increased proteolysis

41
Q

How do glucocorticoids give decreased sensitivity to insulin and decreased glucose uptake?

A

Inhibit translocation of GLUT4, countering effect of insulin
decreased uptake of glucose
in muscle

42
Q

How do glucocorticoids give lipolysis?

A

Decreased sensitivity of insulin - less stimulation of lipogenesis
Decreased glucose uptake - less lipogenesis

Increased lipolysis

43
Q

What is the physiological function of cortisol?

A

Resistance to stress

44
Q

How does cortisol give resistance to stress?

A

Increased supply of glucose

Blood vessels more sensitive to vasoconstrictors
raises blood pressure

45
Q

What other effects does cortisol have?

A

Depression of immune response

Anti-inflammatory effects

46
Q

How does cortisol have anti-inflammatory effects?

A

Inhibits macrophage activity

Inhibits mast cell degranulation

47
Q

What is cortisol used to treat?

A

Prescribed to organ transplant patients

Allergic reactions

48
Q

Outline the hypothalamic pituitary adrenal axis

A

Hypothalamus

Corticotropin releasing hormone (CRH)

Anterior pituitary

Adrenocorticotropic hormone (ACTH)

Adrenal gland

Cortisol

Cortisol inhibits CRH release from hypothalamus
inhibits ACTH release from anterior pituitary

49
Q

What stimulates the hypothalamus to release CRH?

A

Stress

  • fever
  • pain
  • low blood pressure
  • hypoglycaemia
50
Q

What regulates androgen secretion?

A

ACTH

CRH

51
Q

What is regulated more by ACTH and CRH - cortisol or androgens?

A

Cortisol

52
Q

What is DHEA converted to in males? Where does this occur?

A

Testosterone

Testes

53
Q

What is an important source of testosterone before puberty?

A

DHEA

54
Q

What is an important source of testosterone after puberty? What isn’t?

A

Testes themselves synthesise much more testosterone

DHEA becomes insignificant source, because it’s in much smaller amounts

55
Q

What are androgens converted to in females?

A

Oestrogens

56
Q

What is an important source of oestrogens after menopause?

A

DHEA - is the only source!

57
Q

What do androgens promote?

A

Females - libido (sex drive)

Males and females - axillary and pubic hair growth

58
Q

How is the adrenal medulla related to nervous tissue?

A

It is a modified sympathetic ganglion of the ANS

59
Q

How are chromaffin cells related to nervous tissue?

A

Act as post-ganglionic sympathetic nerve fibres

60
Q

What hormones do chromaffin cells release into the blood? What are the relative proportions

A

Adrenaline - 80%

Noradrenaline - 20%

61
Q

Catecholamines are derivates of…?

A

Tyrosine amino acid

62
Q

What are the molecules involved in catecholamine synthesis?

A 
Tyrosine
L-DOPA
Dopamine
Noradrenaline
Adrenaline
63
Q

How is tyrosine converted to L-DOPA?

A

Tyrosine hydroxylase enzyme

64
Q

How is L-DOPA converted to dopamine?

A

Dopa decarboxylase enzyme

65
Q

How is dopamine converted into noradrenaline?

A

Dopamine B-hydroxylase enzyme

66
Q

How is noradrenaline converted into adrenaline?

A

N-methyltransferase enzyme

67
Q

Do all chromaffin cells have N-methyltransferase?

A

No
20% don’t
Hence 20% secrete noradrenaline, not adrenaline

68
Q

What type of GPCR is located in the heart?

A

B1 adrenergic receptors

69
Q

What effects do activated B1 adrenergic receptors have on the heart?

A

Increase heart rate

Increase force of contraction

70
Q

What type of GPCR is located in the lungs?

A

B2 adrenergic receptors

71
Q

What effect do activated B2 adrenergic receptors have on the lungs?

A

Bronchodilation

72
Q

What type of GPCRs are located in blood vessels?

A

A1

B2

73
Q

A1 receptors are located in blood vessels in…

A

Skin, gut

74
Q

B2 receptors are located in blood vessels in…

A

Skeletal muscle

75
Q

What effect do activated A1 adrenergic receptors have in blood vessels in the skin and gut?

A

Vasoconstriction

76
Q

What effect do activated B2 adrenergic receptors have in blood vessels in skeletal muscle?

A

Vasodilation

77
Q

What does vasconstriction of blood vessels in skin and gut and vasodilation of blood vessels in skeletal muscle give?

A

Redistribution of blood flow
To skeletal muscle
Less to skin and gut

78
Q

How does adrenaline give increased heart rate through HCN channels?

A

Increases cAMP
activates HCN channels

PKA
phosphorylaes HCN channels

increased Na+ influx
faster depolarisation
faster heart rate

79
Q

How does adrenaline give increased heart rate through Ca2+ channels?

A 
PKA
phosphoryaltes VGCC channels
increased Ca2+ influx
faster depolarisation
faster heart rate

Endocrinology (14 decks)

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