Adrenal Gland Flashcards

1
Q

Where are the adrenal glands located?

A

at the top of the kidneys

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2
Q

How many arteries do the adrenal glands have?

A

Lots!!! Like seriously loads…

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3
Q

How many veins do the adrenal glands have?

A

One each

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4
Q

What’s the difference between the left adrenal vein + right adrenal vein?

A

Left adrenal vein drains into the renal vein + then the inferior vena carva, right adrenal vein drains into the inferior vena carva

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5
Q

What are the 2 main parts of the adrenal glands?

A

Adrenal cortex + Adrenal medulla

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6
Q

What are the 3 parts of the adrenal cortex?

A

Zona glomerulosa, Zona fasciculata, Zona reticularis

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7
Q

What is the purpose of the adrenal cortex?

A

Secretes corticosteroids, e.g. cortisol

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8
Q

What is the purpose of the adrenal medulla?

A

Secretes catecholamines, e.g. adrenaline

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9
Q

What are the catecholamines released by the adrenal glands?

A

Adrenaline / epinephrine (80%)
Noradrenaline / norepinephrine (20%)
Very small amounts of dopamine

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10
Q

What corticosteroids are released by the adrenal glands?

A
Mineralocorticoids (aldosterone)
Glucocorticoids (cortisol)
Sex steroids (androgens, oestrogens)
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11
Q

What cells is the adrenal medulla made up of?

A

Chromaffin cells → these release the catecholamines

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12
Q

What is the purpose of the zona glomerulosa? What does it look like?

A

Produces aldosterone, thin layer of clear cells

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13
Q

What is the purpose of the zona fasciculata? What does it look like?

A

Produces cortisol + sex steroids, thick layer of compact cells

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14
Q

What is the purpose of the zona reticularis? What does it look like?

A

Produces cortisol + sex steroids, thin layer of compact cells

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15
Q

What is the precursor compound for corticosteroids?

A

Cholesterol

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16
Q

What is the next common compound in the synthesis of mineralocorticoids + glucocorticoids?

A

Progesterone

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17
Q

What is an enzyme?

A

A protein that catalysts a specific reaction

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18
Q

How is progesterone synthesised from cholesterol?

A

Cholesterol → Pregnenolone → Progesterone

Enzymes: side chain cleavage enzyme, 3 beta hydroxy steroid dehydrogenase

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19
Q

What is Step 1 of aldosterone synthesis from progesterone?

A

progesterone → 11 deoxycorticosterone

enzyme: 21 HYDROXYLASE

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20
Q

What is Step 2 of aldosterone synthesis from progesterone?

A

11 deoxycorticosterone → corticosterone

enzyme: 11 HYDROXYLASE

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21
Q

What is Step 3 of aldosterone synthesis from progesterone?

A

Corticosterone → aldosterone

enzyme: 18 HYDROXYLASE

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22
Q

What is Step 1 of cortisol synthesis from progesterone?

A

progesterone → 17 hydroxy-progesterone

enzyme: 17 HYDROXYLASE

23
Q

What is Step 2 of cortisol synthesis from progesterone?

A

17 hydroxy-progesterone → 11 deoxy-cortisol

enzyme: 21 HYDROXYLASE

24
Q

What is Step 3 of cortisol synthesis from progesterone?

A

11 deoxy-cortisol → cortisol

Enzyme: 11 HYDROXYLASE

25
What is the main function of aldosterone?
Conserves body Na+ through stimulating Na + reabsorption + H2O reabsorption + raising blood volume
26
What is the mechanism of action of aldosterone?
- Stimulates Na+ reabsorption in distal convoluted tubule and cortical collecting duct in kidney (and in sweat glands, gastric glands, colon) - Water follows Na+ via osmosis - Turns on Na+/K+ pumps - Stimulates K+ and H+ secretion in DCT and cortical collecting duct
27
How is aldosterone release regulated?
Through the hormone "renin"
28
When is renin released?
Renin is released when blood pressure falls in the kidneys
29
What are the effects of renin?
- Decreased renal perfusion pressure (normally associated with decreased arterial BP) - Increased renal sympathetic activity (direct to JGA cells) - Decreased Na+ load to top of loop of Henle (macula densa cells)
30
What cascade of reactions does renin stimulate?
Angiotensinogen → Angiotensin I → Angiotensin ll Renin does the first conversion, ACE does the second conversion Angiotensin ll regulates Aldosterone
31
How does angiotensin 11 affect the adrenals?
Activativation of enzymes: side chain cleavage, 3 hydroxysteroid dehydrogenase, 21,11, 18 Hydroxylase
32
What is the main function of cortisol?
``` - Normal stress response Metabolic effects peripheral protein catabolism hepatic gluconeogenesis increased blood glucose concentration fat metabolism (lipolysis in adipose tissue) enhanced effects of glucagon and catecholamines Weak mineralocorticoid effects Renal and cardiovascular effects excretion of water load increased vascular permeability ```
33
How is cortisol regulated?
Too much cortisol causes negative feed back: → CRH is inhibited from the hypothalamus → ACTH is inhibited from the anterior pituitary gland
34
What is the affect of ACTH on the adrenal glands?
``` Activation of the following enzymes: → Side Chain Cleavage → 3 Hydroxysteroid dehydrogenase → 21 hydroxylase → 11 hydroxylase → 17 hydroxylase ```
35
What is meant by a cortisol diurnal rhythm?
Cortical + ACTH both have a steep rise in the morning + steeply decline through the day
36
What is Addison’s disease?
Primary adrenal failure - autoimmune disease where the immune system decides to destroy the adrenal cortex
37
What is the most common cause of Addison's disease?
Tuberculosis of the adrenal glands.
38
What is the effect of Addison's disease on the hormones?
Adrenal gland hormones aren't produced, ACTH and MSH are overproduced.
39
What is MSH?
Melanocyte-stimulating hormone
40
What are some symptoms of Addison's disease?
``` Hyperpigmentation/ Tan skin Hypotension/ low blood pressure Low salt levels Autoimmune Vitiligo Gastrointestinal problems ```
41
Why does Addison's Disease cause tan skin / hyperpigmentation?
ACTH is cleaved from pro-opio-melano-cortin (large precursor protein) MCH is also cleared from the same molecule High levels of ACTH = high levels of MCH
42
What are the symptoms of an Adrenal / Addisonian Crisis?
→ Severe vomiting, nausea or diarrhoea → abdominal pain, body pains + weakness → syncope (loss of conciousness + muscle strength) → confusion, convulsions → Low blood pressure, High potassium (hyperkalemia) and low sodium (hyponatremia)
44
How is an Addisonian crisis treated?
→ Rehydrate with normal saline → Give dextrose to prevent hypoglycaemia which could be due to the glucocorticoid deficiency → Give hydrocortisone or another glucocorticoid
45
What can cause an excess of cortisol?
→ pituitary tumour = excess ACTH | → adrenal tumour = excess cortisol
46
What is Cushing' syndrome?
Hypercortisolism, having excess cortisol
47
What are symptoms of Cushing's syndrome?
→ stretch marks + fat pads on the back → centripetal obesity (abdominal weight gain) → thin arms and legs + proximal myopathy → moon face + red cheeks → high blood pressure → impaired wound healing + mental changes
48
What are 4 possible causes of Cushing's syndrome?
→ Too many oral steroids (corticosteroids) → Pituitary tumour → Adrenal tumour → ectopic ACTH (lung cancer)
49
Where is the adrenal medulla derived from?
Ectodermal neural crest
50
What is the precursor for Adrenaline+ Noradrenaline synthesis?
Tyrosine
51
How are catechalamines stored t released?
Stored in cytoplasmic granules | Released in response to ACH released from pre-ganglionic sympathetic neurones
52
What is the role of catecholamines?
‘Fight or flight response’ | e.g. tachycardia, sweating, increased blood glucose, alertness, vasoconstriction
53
How are catecholamines transported in the bloodstream?
Bound to albumin
54
How are catecholannines degraded?
By 2 hepatic enzymes: catechol-O-methyl transferase monoamine oxidase
55
What are the consequences of excess cortisol?
Changes in metabolism which can lead to gain in weight