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Lily BRS Endo > The Adrenal Glands > Flashcards

The Adrenal Glands Flashcards

1
Q

Where are the adrenal glands?

A

Above the kidneys

Right at the back of the abdomen and protected by the ribs

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2
Q

What is the blood supply to and from the adrenal glands like?

A

Supplied by many (57) arteries that branch of the abdominal aorta

But drain into only 1 vein. The inferior vena cava

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3
Q

How does each gland drain specifically?

A

The right drains directly into the inferior vena cava

The left drains into the renal vein then the ivc

(Be able to draw this)

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4
Q

What is the anatomy of the adrenal glands?

A

Outer cortex and an inner medulla

The cortex is comprised of three layers: zona glomerulosa. Zona fasciculata. Zona reticulatis

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5
Q

What does the cortex secrete?

A

Corticosteroids and sex hormones

Eg. Cortisol

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6
Q

What does the medulla secrete?

A

Catecholamines

Eg. Adrenaline and noradrenaline

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7
Q

What are catecholamines?

A

Secreted by adrenal medulla

Synthesised from amino acids

Eg. Adrenaline

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8
Q

What are corticosteroids?

A

Secreted by adrenal cortex

Synthesised from cholesterol

Includes: mineralcorticoids (aldosterone). Glucocorticoids (cortisol) and sex steroids (oestrogens and androgens)

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9
Q

Which part of the adrenal cortex makes what?

A

Zona glomerulosa: aldosterone (mineralocorticoid)

Zona fasciculata and zona reticularis: cortisol (glucocorticoid) and tiny amounts of androgens and oestrogens

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10
Q

What is an enzyme?

A

Protein that catalysed a specific reaction

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11
Q

How are mineralocorticoids formed (aldosterone) ?

A

Cholesterol —> pregnenolone (side chain cleavage enzyme)

Pregnenolone —> progesterone (3 beta hydroxy steroid dehydrogenase/ 3 beta HSD)

Progesterone —> 11 deoxy corticosterone (21 hydroxylase)

11 deoxy corticosterone —> corticosterone ( 11 hydroxylase)

Corticosterone —> aldosterone (18 hydroxylase)

For aldosterone it’s 21,11,18

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12
Q

How are glucocorticoids formed (cortisol)?

A

Cholesterol —> pregnenolone (side chain cleavage)

Pregnenolone—> progesterone (3 beta HSD)

Progesterone —> 17 hydroxy progesterone (17 hydroxylase)

17 hydroxy progesterone —> 11 deoxy cortisol (21 hydroxylase)

11 deoxy cortisol —> cortisol (11 hydroxylase)

Cortisol goes 17,21,11

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13
Q

What does aldosterone do?

A

Main effect is for sodium reabsorbtion in the kidney

Stimulates Na+ reabsorbtion in distal convoluted tubule and collecting duct

Also stimulates K+ and H+ secretion

It switches on the Na+/K+ ATPase

This increases water reabsorbtion and blood volume

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14
Q

How is aldosterone regulated?

A

Renin

Decreased renal perfusion pressure (associated with decreased arterial blood pressure)

Increased renal sympathetic activity (direct to juxtaglomerular apparatus cells) (these feel the change is pressure)

Decreased Na+ load to top of loop of henle

So a high BP surprises renin

Renin—>aldosterone—> raises BP

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15
Q

How does renin affect aldosterone secretion?

A

The liver releases angiotensin

Renin converts angiotensin to angiotensin I

ACE converts angiotensin 1 to angiotensin II

Angiotensin II regulates aldosterone secretion

It activates the enzymes: side chain cleavage, 3 beta HSD, 21 hydroxylase, 11. Hydroxylase, 18 hydroxylase

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16
Q

What does cortisol do?

A

Normal stress response (fight or flight)

Metabolic effects: peripheral protein catabolism, gluconeogenesis, increases blood glucose levels, lipolysis in adipose, enhanced effect of glucagon and catecholamines

Weak mineralocorticoid effects

Renal and cardiovascular effects: excretion of water load, increased vascular permeability

17
Q

How is cortisol secretion regulated?

A

ACTH (adrenocorticotropic hormone)

18
Q

What does the hypthalamo pituitary adrenal axis look like?

A

Hypothalamus: CRH (corticotropin releasing hormone)

Pituitary: ACTH (adrenocorticotropic hormone)

Adrenal glands: cortisol

Cortisol has a negative feedback effect on both the hypothalamus and pituitary (should be able to draw this)

19
Q

What is the effect of ACTH on the adrenal glands?

A

Activated enzymes:

side chain cleavage

3 beta HSD

21 hydroxylase

11 hydroxylase

17 hydroxylase

20
Q

Cortisol has a diurnal rhythm, what does this mean?

A

Follows the circadian cycle

Lowest at midnight

Peaks around 9am

21
Q

What is Addison’s disease?

A

Primary adrenal failure

Autoimmune disease where the immune system destroys the adrenal cortex, or more commonly caused by tuberculosis

Doesn’t produce enough cortisol or aldosterone

Pituitary secretes lord of ACTH due to lack of negative feedback (And MSH (melanocyte stimulating hormone) this helps with tanning

22
Q

What are some symptoms of addisons?

A

Low blood pressure

Vitiligo

Tanning

Weight loss

Nausea

Diarrhoea

Vomiting

Crisis: syncope, fever, convulsions, hypoglycaemia, hyponatraemia, vomiting

23
Q

How is addisons treated?

A

Hydrocortisone or another glucocorticoid (such as pregmisolone)

To treat a crisis, rehydrate with saline, give dextrose to prevent hypoglycaemia

24
Q

What is Cushing’s syndrome?

A

An excess of cortisol

May be due to an adrenal tumour or a pituitary tumour, taking steroids by mouth, ectopic ACTH (lung cancer)

25
Q

What are some symptoms of cushings?

A

Depression

Fat pads

Easy bruising

Red stretch marks

Poor wound healing

Weak muscles

Diabetes

Lemon on sticks

Thin skin

Proximal myopathy

Moon face

26
Q

How are catecholamines made (adrenaline and noradrenaline)?

A

FroM tyrosine

Then tyrosine

Then noradrenaline

Then adrenaline (same as before but it has a methyl group)

27
Q

What do catecholamines do?

A

Fight or flight response (tachycardia, sweating, increased blood glucose)

They are stored in cytoplasmic granules and released in response to acetylcholine from preganglionic sympathetic neurones

They circulate bound to albumin

Degraded by monoamine oxidises and catechol-O-methyl transferase

Lily BRS Endo (10 decks)

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