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2 MEH > 17 Adrenal Glands > Flashcards

17 Adrenal Glands Flashcards

1
Q

Where are the adrenal glands located?

A

On top of kidneys- attached to diaphragm

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2
Q

What are the main components which make up the adrenal glands?

A
  • Capsule
  • Cortex
  • Medulla
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3
Q

What layers make up the cortex of the adrenal glands?

A

Zona glomerulosa, zona fascicolata, zona reticularis

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4
Q

What hormone does each layer of the cortex produce?

A

CORTICOSTEROIDS:

1) zona glomerulosa- mineralcorticoids (SALT)
2) zona fasiculata -glucocorticoids (SUGAR)
3) zona reticularis- glucocorticoids+small amounts of androgens (SEX)

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5
Q

What cells is the medulla made up of?

A

Chromaffin cells

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6
Q

What do the chromaffin cells produce?

A

80% Adrenaline, 20% Noradrenaline

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7
Q

What are steroid hormones synthesised from?

A

Cholesterol

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8
Q

How do steroid hormone function?

A

=Lipid soluble–> bind to nuclear receptors–> modulate gene transcription

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9
Q

Give examples of steroid hormones.

A

Glucocorticoids

Mineralocorticoids

Androgens

Oestrogen

Progestins

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10
Q

How do corticosteroids exert their actions?

A

1) Diffuse across plasma membrane
2) Bind to glucocorticoid receptors- cause dissociation of CHAPERONE PROTEINS
3) Receptor ligand translocates to nucleus- receptors bind to glucocorticoid response elements:
* (GREs)/transcription factors*

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11
Q

Name the most abundant mineralocorticoid.

A

Aldosterone

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12
Q

What are the carrier proteins for aldosterone?

A

Albumin (+transcortin)

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13
Q

How does aldosterone exert its effects?

A
  • =steroid hormone
  • Regulates gene transcription -intracellular
  • Lipophilic
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14
Q

What is the function of Aldosterone?

A

Regulates plasma sodium and potassium- arterial blood pressure

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15
Q

Where in the body does aldosterone exert its actions?

A

DISTAL TUBULES and COLLECTING DUCTS of NEPHRON

Promotes expression of Na+/K+ pump, promotes reabsorption of Na+ and excretion of K+

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16
Q

Which part of the adrenal cortex synthesises and releases aldosterone?

A

Zona glomerulosa

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17
Q

What is the RAAS (renin-angiotensin-aldosterone system)?

A

System that regulates :

  • blood pressure
  • fluid electrolyte
  • balance
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18
Q

What organs/tissues are involved in the RAAS?

A
  • Lungs
  • Liver
  • Kidney
  • Adrenal glands (cortex)
  • Arterioles
  • Posterior pituitary
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19
Q

Outline how the RAAS works in 5 steps.

A
  1. Decreased renal perfusion- drop in blood pressure, increased sympathetic tone from baroreceptor activation- increased renin release from kidney
  2. Angiotensinogen constitutively released into blood by liver
  3. Angiotensinogen cleaved by renin to angiotensin I​
  4. ACE (angiotensin converting enzyme) released in lungs cleaves angiotensin I​toangiotensin I​I
  5. Angiotensin II causes:
    1. Vasoconstriction
    2. Adrenal Cortex releases aldosterone: Increased water and Na+reabsorption into blood (increased expression of sodium potassium pump)
    3. Posterior pituitary releases ADH: Translocation of aquaporin channels aids reabsorption of water back into the blood
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20
Q

What type of drug may be given as an antihypertensive?

A

ACE inhibitors

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21
Q

What causes primary hyperaldosteronism?

A

Defect in adrenal cortex eg:

  1. Bilateral idiopathic adrenal hyperplasia (most common)
  2. Conn’s syndrome: Aldosterone secreting adrenal adenoma
  • LOW RENIN LEVELS= high aldosterone:renin ratio
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22
Q

What causes secondary hyperaldosteronism?

A

Overactivity of RAAS

  1. Renal artery stenosis
  2. Renin producing tumour= rare
  • HIGH RENIN LEVELS (low aldosterone:renin ratio)
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23
Q

What’s the best way to distinguish between primary and secondary hyperaldosteronism?

A

High renin levels= secondary

Low renin levels= primary

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24
Q

What are the signs/symptoms of hyperaldosteronism?

A
  1. High BP
  2. Left ventricular hypertrophy
  3. Stroke
  4. Hypernatraemia
  5. Hypokalaemia
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25
Q

How might hyperaldosteronism be treated?

A

(Depends of type)

  1. Removal of aldosterone-producing adenomas
  2. Spironolactone=mineralcorticoid receptor antagonist
26
Q

What’s the most abundant corticosteroid?

A

Cortisol

27
Q

What hormone stimulates the synthesis and release of Cortisol from the Zona fasiculata?

A

Adrenocorticotropic hormone (ACTH)

28
Q

What is the carrier protein for cortisol? (in plasma)

A

Transcortin

29
Q

How does a cortisol receptor exert its effects?

A

Regulating gene transcription

30
Q

List the actions of cortisol (6):

A
  1. Increase protein breakdown in muscle
  2. Increased lipolysis in fat
  3. Increased gluconeogenesis in liver
  4. Resistance to stress (increased supply of glucose, raise BP- vessels more sensitive to vasoconstrictors)
  5. Anti-inflammatory effects (inhibit macrophage activity+ Mast cell degranulation)
  6. Depression of immune response (prescribed organ transplant patients)
31
Q

Fill in the missing labels in the following diagram:

A

j

32
Q

What are the actions of glucocorticoid hormones on metabolism?

A
  1. Increased glucose production
  2. Breakdown of protein
  3. Redistribution of fat
33
Q

What is cushing’s syndrome?

A

Chronic excessive exposure to cortisol

34
Q

What are the 2 main types of causes of cushing’s syndrome?

A
  1. External (most common)
  2. Endogenous (rare)
35
Q

What’s the most common external cause of Cushing’s syndrome?

A

Prescribed glucocorticoids

36
Q

What are the 3 endogenous causes of Cushing’s syndrome?

A
  1. Cushing’s disease: benign pituitary adenoma secreting ACTH
  2. Adrenal Cushing’s: excess cortisol produced by adrenal tumour
  3. Non pituitary-adrenal tumours producing ACTH e.g. small cell lung cancer
37
Q

Give 2 examples of steroid drugs.

A
  1. Prenisolone
  2. Dexamethasone
38
Q

What effects does Prednisolone have?(2)

A
  1. Anti-inflammatory effects
  2. Immunomodulatory effects (eg supress immune reaction to organ transplantation)
39
Q

What is Prednisolone used to treat?

A
  1. Asthma
  2. Inflammatory bowel disease
  3. Rheumatoid arthritis
  4. Other autoimmune conditions
  5. Supress immune reaction to organ transplant
40
Q

Describe the side effects of steroid drugs like prednisolone and dexmethasone.

A

Same as effects of high levels of cortisol

+ can have mineral corticoid effects

41
Q

Why should steroid dosage be reduced gradually and not stopped suddenly?

A

Down regulation due to negative feedback

42
Q

What is Addison’s disease?

A

Chronic adrenal insufficiency

43
Q

What are the causes of Addison’s disease? (5)

A
  1. Autoimmune response- causing destructive atrophy
  2. Complication of Tuberculosis
  3. (Much rarer) Fungal infection
  4. (Much rarer) Adrenal cancer
  5. (Much rarer) Adrenal haemorrhage (following trauma)
44
Q

What are the signs and symptoms of Addison’s disease?

A
  1. Postural hypotension
  2. Lethargy
  3. Weight loss
  4. Anorexia
  5. Increased skin pigmentation
  6. Hypoglycaemia
45
Q

Why might Addison’s disease cause hyperpigmentation?

A
  • Decreased cortisol
  • Negative feedback anterior pituitary reduced
  • More POMC require to synthesise ACTH
  1. POMC increases ACTH and MSH production
  2. ACTH itselfactivates melanocortin receptors on melanocytes
46
Q

What is the ‘Addisonian crisis’?

A

Life threatening emergency- due to adrenal insufficiency

47
Q

What is an addisonian crisis precipitated by?

A
  1. Severe stress
  2. Salt deprivation
  3. Infection
  4. Trauma
  5. Cold exposure
  6. Over exertion
  7. Abrupt steroid drug withdrawal
48
Q

What are the symptoms of an addisonian crisis?

A
  • Nausea
  • Vomiting
  • Pyrexia
  • Hypotension
  • Vascular collapse
49
Q

How do you treat an Addisonian crisi?

A
  • Fluid replacement
  • Cortisol
50
Q

Where are (weak) androgens secreted from?

A

Zona reticularis

51
Q

What androgens are secreted from the zona reticularis in the adrenal cortex?

A
  • DHEA: Dehydroepiandrosterone
  • Androstenedione
52
Q

Which hormones (partially) regulate androgen release from the zona reticularis?

A
  • ACTH
  • CRH
53
Q

What happens to DHEA in males?

A

Converted to testosterone in testes

(insignificant after puberty)

54
Q

What do androgens do in females/ what happens to them?

A
  • Promote libido
  • Converted to oestrogens

(only source of oestrogens after menopause)

55
Q

What do androgens do in both sexes?

A

Promote axillary and pubic hair growth

56
Q

Decribe the Adrenal Medulla:

A
  • Modified sympathetic ganglion fo ANS
  • Chromaffin cells lack axons
  • –> BUT act as post ganglionic nerve fibres–> release hormones into blood

Adrenaline 80%

Noradrenaline 20%

57
Q

What receptors do adrenaline and noradrenaline act on? (and what pathways do they activated)

A
58
Q

Fill in the gaps with the type of GPCR:

A
59
Q

What is a Phaeochromocytoma?

A

Rare

Chromaffin cell tumour

Catecholamine-secreting tumour

60
Q

What are the signs/symptoms of a phaeochromocytoma?

A
  • Severe hypertension
  • Headaches
  • Palpitations
  • Diaphoresis (excessive sweating)
  • Anxiety
  • Weight loss
  • Elevated blood glucose
61
Q

Fill in the missing gaps:

A

2 MEH (18 decks)

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