Adrenal Glands Flashcards

1
Q

What are the 2 components of the adrenal gland?

A
  • Adrenal cortex.

- Adrenal medulla.

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2
Q

List the classes of steroid hormones synthesised and released from the adrenal cortex.

A

1 - Glucocorticoids.

2 - Mineralocorticoids.

3 - Adrenal androgens.

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3
Q

What class of hormones are synthesised and released from the adrenal medulla?

A

Catecholamines.

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4
Q

List the layers of the adrenal cortex from superficial to deep.

A

1 - Zona glomerulosa.

2 - Zona fasciculata.

3 - Zona reticularis.

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5
Q

What class of hormones are synthesised at the zona glomerulosa?

A

Mineralocorticoids.

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6
Q

What class of hormones are synthesised at the zona fasciculata?

A

Glucocorticoids.

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7
Q

What class of hormones are synthesised at the zona reticularis?

A

Androgens.

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8
Q

List 2 mineralocorticoids.

A

1 - Aldosterone.

2 - DOC.

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9
Q

Give an example of a glucocorticoid.

A

Cortisol.

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10
Q

List 2 adrenal androgens.

A

1 - DHEA.

2 - Androstenedione.

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11
Q

What is the precursor molecule steroidogenesis?

A

Cholesterol.

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12
Q

What is the name of the disease that causes an excess of glucocorticoids?

A

Cushing’s syndrome.

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13
Q

What is the name of the disease that causes an excess of mineralocorticoids?

A

Conn’s syndrome.

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14
Q

What is the name of the disease that causes an excess of adrenal androgens?

A

Hyperandrogenism.

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15
Q

What is the name of the disease that causes an excess of catecholamines?

A

Phaeochromocytoma (a tumour).

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16
Q

List 2 causes of excess adrenal activity.

A

1 - Adrenal tumours.

2 - Congenital adrenal hyperplasia.

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17
Q

Are steroid hormones lipophilic or hydrophilic?

A

Lipophilic.

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18
Q

What are permissive actions of drugs?

A

Actions that do not directly initiate but allow other actions to occur in the presence of other factors.

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19
Q

List 3 actions of glucocorticoids.

A

1 - Increase glucose mobilisation.

2 - Maintenance of circulation.

3 - Immunomodulation.

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20
Q

List 3 ways by which glucocorticoids increase glucose mobilisation.

A

1 - By augmenting gluconeogenesis.

2 - Via amino acid generation.

3 - By increasing lipolysis.

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21
Q

List 2 ways by which glucocorticoids maintain circulation.

A

1 - By maintaining vascular tone.

2 - By controlling the salt and water balance.

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22
Q

What is the role of glucocorticoids in immunomodulation?

A

Glucocorticoids dampen the immune response.

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23
Q

List the proteins that bind to glucocorticoids in the blood, and give the relative abundance of each.

A
  • 90% of glucocorticoids are bound to corticosteroid-binding globulin (CBG).
  • 5% bound to albumin.
  • 5% free and bioavailable.
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24
Q

What is the effect of inflammation on corticosteroid-binding globulin (CBG)?

A

CBG decreases with inflammation.

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25
Q

Define diurnal.

A

Occurring during daylight hours.

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26
Q

Define circadian.

A

Occurring once every 24 hours.

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27
Q

When are the peaks of cortisol concentration during the day?

A

At 7 am and 3pm.

28
Q

Define stress.

A

The sum of the body’s responses to adverse stimuli.

29
Q

List 5 adverse stimuli that cause biological stress.

A

1 - Infection.

2 - Trauma (physical and psychological).

3 - Haemorrhage.

4 - Illness.

5 - Exercise.

30
Q

What is the activity of DOC relative to aldosterone?

A

Doc has 3% activity of aldosterone.

31
Q

What is the main function of mineralocorticoids?

A

To control salt and water balance.

32
Q

List 5 sites of the body at which mineralocorticoids act.

A

1 - Kidneys.

2 - Colon.

3 - Pancreas.

4 - Salivary glands.

5 - Sweat glands.

33
Q

What is the function of renin?

A

To increase blood pressure.

34
Q

Describe the process by which mineralocorticoids are regulated.

A

1 - A decrease in renal perfusion pressure causes juxtaglomerular cells to release renin.

2 - Renin converts angiotensin into angiotensin I, which is then converted into angiotensin II.

3 - Angiotensin II stimulates the angiotensin II receptor to release aldosterone and to cause vasoconstriction.

4 - Aldosterone binds to mineralocorticoid receptors to promote sodium retention to further increase blood pressure.

35
Q

What stimulates angiotensin production?

A

Vasoconstriction.

36
Q

Where is angiotensin produced?

A

In the liver.

37
Q

List 2 factors that increase renin release (excluding a decrease in renal perfusion pressure).

A

1 - β-adrenergic action.

2 - Presence of prostaglandins.

38
Q

List 2 factors that decrease renin release.

A

1 - Presence of atrial natriuretic peptide.

2 - Presence of dopamine.

39
Q

How do mineralocorticoids affect the pancreas, sweat glands, salivary glands and colon?

A

They increase sodium reabsorption.

40
Q

List 2 functions of mineralocorticoids other than control of salt and water balance.

A

1 - Myocardial collagen production.

2 - Role in cardiac fibrosis / remodelling.

41
Q

How do mineralocorticoid receptors promote sodium retention?

A

By increasing the transcription of apical Na channels and Na/K pumps.

42
Q

For which molecules do mineralocorticoids have an affinity?

A

1 - Mineralocorticoids (e.g. aldosterone).

2 - Cortisol! (receptors have a low specificity).

43
Q

Why aren’t mineralocorticoid receptors inundated by cortisol?

A

Cortisol is converted into cortisone by 11β-hydroxysteroid dehydrogenase, for which the receptors do not have an affinity. This occurs before it is able to reach the receptor.

44
Q

Why might ingestion of liquorice result in an increase in blood pressure?

A

Liquorice inhibits the activity of 11β-hydroxysteroid dehydrogenase, allowing cortisol to reach and bind to the mineralocorticoid receptor.

45
Q

Where are androgens produced outside of the adrenal gland?

A

1 - Ovaries.

2 - Testes.

3 - Adipose tissue.

46
Q

How are adrenal androgens different from androgens produced elsewhere?

A

Adrenal androgens are weaker.

47
Q

What is the function of adrenal androgens that is specific to postmenopausal women?

A

Adrenal androgens are oestrogen precursors in postmenopausal women.

  • Postmenopausal women no longer produce oestrogen at the ovaries.
48
Q

What regulates the production of adrenal androgens?

A

By ACTH.

49
Q

What regulates the production of non-adrenal androgens?

A

By gonadotropins.

50
Q

List 3 functions of androgens.

A

1 - Puberty initiation.

2 - Hair growth.

3 - Sexual interest.

51
Q

What is the predominant cell type of the adrenal medulla?

A

Sympathetic ganglia.

52
Q

What type of fibres supply the ganglia of the adrenal medulla?

A

Sympathetic pre-ganglionic neurones.

53
Q

What neurotransmitter is used to stimulate the ganglia of the adrenal medulla?

A

Acetylcholine.

54
Q

What do the ganglia of the adrenal medulla synthesise?

A

Catecholamines.

55
Q

List 3 catecholamines.

A

1 - Adrenaline.

2 - Noradrenaline.

3 - Dopamine.

56
Q

Which enzyme is necessary for the conversion of noradrenaline into adrenaline?

A

Phenylethanolamine-N-methyltransferase.

57
Q

How do the products of the ganglia of the adrenal medulla enter the blood?

A

They diffuse directly into adrenal capillaries.

58
Q

Describe the relative amounts of catecholamines produced by the adrenal medulla.

A
  • 80% of catecholamines produced is adrenaline.
  • 20% of catecholamines produced is noradrenaline.
  • Dopamine is produced in trace amounts.
59
Q

Give an example of a permissive effect of cortisol.

A

High cortisol levels are necessary for normal catecholamine synthesis.

60
Q

What is the precursor for catecholamine synthesis?

A

Tyrosine.

61
Q

To which receptors to catecholamines bind?

A

Adrenergic receptors.

62
Q

What is the effect of alpha adrenergic receptor stimulation?

A

Vasoconstriction.

63
Q

What is the main effect of β1 adrenergic receptor stimulation?

A

To increase cardiac output.

64
Q

What is the main effect of β2 adrenergic receptor stimulation?

A

Smooth muscle relaxation in the bladder, uterus and bronchioles.

65
Q

List 2 effects of β3 adrenergic receptor stimulation.

A

1 - Regulation of lipolysis.

2 - Regulation of thermogenesis.

66
Q

What is the general function of catecholamines?

A

To stimulate fight or flight responses (via the sympathetic nervous system).

67
Q

List 2 examples of adrenal tumours.

A

1 - Adrenal incidentaloma.

2 - Adrenocortical carcinoma.