Week 3- The Adrenal Gland Flashcards

1
Q

Where are the adrenal glands found?

A

Just above the kidneys

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2
Q

How many adrenal arteries are there?

A

Lots (57)

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3
Q

How many adrenal veins are there?

A

1

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4
Q

Where do left adrenal veins drain?

A

Rénal vein

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5
Q

Where do right adrenal veins drain?

A

Inferior vena cava

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6
Q

What makes up the adrenal cortex?

A

Zona glomerulosa (outermost layer), fasciculata (middle layer) and reticularis (inner layer)

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7
Q

What does the adrenal cortex do?

A

Secretes corticosteroids

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8
Q

What does the adrenal medulla do?

A

Secretes catecholamines eg adrenaline/noradrenaline

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9
Q

What does the zona glomerulosa synthesize?

A

Aldosterone

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10
Q

What do the zona fasciculata and reticularis synthesize together?

A

Cortisol (androgens & œstogen)

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11
Q

What molecule do steroids come from?

A

Cholesterol

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12
Q

What are the 3 classes of corticosteroids?

A
Mineralocortocoids (aldosterone )
Glucocorticoids (cortisol)
Sex steroids (androgens, œstrogens)
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13
Q

What is the essential characteristic a steroid must have?

A

It must come from cholesterol

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14
Q

Describe how aldosterone is synthesized

A

The side chain of cholesterol is cleaved creating pregnenolone

Pregnenolone is oxidized to progesterone via 3 beta hydroxylation steroid dehydrogenase

An OH group is added at position 21 (11 deoxy corticosterone)

An OH group is added at position 11 (corticosterone)

An OH group is added at position 18 (aldosterone)

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15
Q

How is aldosterone output controlled?

A

By regulating the enzymes that hydroxylate progesterone to produce aldosterone

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16
Q

What is the enzyme that converts pregnenolone to progesterone?

A

3 beta hydroxy steroid dehydrogenase

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17
Q

What is a main role of aldosterone?

A

Control of blood pressure

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18
Q

What stimulates production of renin?

A

A drop in blood pressure

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19
Q

What is the effect of angiotensin II on the adrenals?

A

Causes activation of 3 hydroxysteroid dehydrogenase, 21/11/18 hydroxylase and side chain cleavage enzymes so aldosterone is produced

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20
Q

What are the 4 main physiological effects of cortisol?

A

Normal stress response
Metabolic effects
Weak mineralocorticoid effects
Renal and cardiovascular effects

21
Q

What hormone controls cortisol secretion and where is it produced?

A

ACTH, produced in pituitary gland in brain

22
Q

What is the effect of ACTH on the adrenals?

A

Activation of 3 hydroxysteroid dehydrogenase, 21/11/18 hydroxylase and side chain cleavage enzyme

23
Q

What type of rhythm does cortisol have?

A

Diurnal/circadian

24
Q

What is Addison’s disease

A

Primary adrenocortical failure- Autoimmune condition where the immune system destroys the adrenal cortex.

25
Q

What happens hormone wise in Adddisons disease?

A

Pituitary starts secreting lots of ACTH and therefore MSH

26
Q

What are symptoms of Addison’s disease?

A

Hyperpigmentation of skin, vitiligo, low BP, weakness, weight loss, nausea, diarrhea, vomiting

27
Q

Why do patients with Addison’s disease have low blood pressure?

A

They have no cortisol or aldosterone

28
Q

How can Addision’s disease result in death?

A

Lack of cortisol and aldosterone causes loss of salt, reducing BP eventually causing death

29
Q

What is Cushing’s syndrome?

A

Too much cortisol or other glucocorticoid

30
Q

What are visible symptoms of Cushing’s syndrome?

A

Fat pads, stretch marks, moon face, poor wound healing, easy bruising, thin skin, diabetes, hypertension

31
Q

What are the 4 main causes of Cushing’s syndrome?

A

Taking steroids by mouth
Pituitary dependant
Ectopic ACTH
Adrenal adenoma/carcinoma

32
Q

What does the adrenal medulla secrete?

A

Catecholamines (adrenaline/epiphrine [80%] and noradrenaline/norepiphrine [20%] )

33
Q

What is the adrenal medulla derived from?

A

The ectodermal neural crest

34
Q

What is the precursor for adrenaline and noradrenaline synthesis?

A

Tyrosine

35
Q

Where are catecholamines stored?

A

Cytoplasmic granules

36
Q

When are chatecholamines released and from where?

A

Released in response to Ach from preganglionic sympathetic neurones

37
Q

How do Adr and NA circulate?

A

Bound to albumin

38
Q

What is the role of catecholamines? What physiological responses occur to achieve this role

A

Fight or flight response

Tachycardia, sweating, higher blood glucose, alertness, vasoconstriction

39
Q

What type of enzymes degrade catecholamines?

A

Hepatic

40
Q

What are the names of the 2 enzymes that degrade catecholamines?

A

Monoamine oxidase

Catechol-O-methyl transferase

41
Q

How is the balance of sodium and potassium ions affected in Addison’s disease?

A

More sodium ions are removed than ideal leading to low sodium

Less potassium is removed than ideal leading to high potassium

42
Q

What is the medical name for low sodium?

A

Hyponatraemia

43
Q

What is the medical name for high potassium?

A

Hyperkalaemia

44
Q

What is the action of aldosterone on sodium and potassium levels in the blood and urine?

A

Removes sodium from urine into blood, moves potassium from blood to urine

45
Q

The loss of cortisol In Addison’s disease causes the levels of which hormone to rise?

A

ACTH

46
Q

How does excess ACTH lead to hyperpigmentation in Addison’s?

A

ACTH is made from a long peptide which is broken into many segments, one of these segments is the molecule MSH that stimulates melanin production so if more ACTH is made so is more melanin leading to hyperpigmentation

47
Q

Describe how cortisol is synthesised from cholesterol

A

Cholesterol is converted to progesterone
Progesterone is converted to 17 OH prog by adding a hydroxyl group at position 17
17 OH prog is converted to 11 deoxycortisol
11 deoxycortisol is converted to cortisol

48
Q

Describe how oestrogen is synthesised from cholesterol

A

Cholesterol is converted to progesterone
Progesterone is converted to 17 OH prog
17 OH prog is converted to sex steroids
Sex steroids are converted to androgens and then to oestrogen