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ENDOCRINOLOGY > The adrenal gland > Flashcards

The adrenal gland Flashcards

1
Q

Where are the adrenal glands

A

Above the kidneys

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2
Q

veins and arteries of adrenal glands

A

Left adrenal vein drains into renal vein

Right adrenal vein drains into IVC (inferior vena cava)

Both adrenals have many arteries but only one vein

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3
Q

MICroanatomy of adrenal glands and where exactly is adrenaline made and cortisol

A

Adrenal medulla secretes catecholamines (adrenaline)

Adrenal cortex secretes corticosteroids (cortisol)

Adrenal cortex made up of zona reticularis, zona fasciculata, zona glomerulosa

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4
Q

What are catecholamines

A

Adrenaline / epinephrine (80%)

Noradrenaline / norepinephrine (20%) (dopamine)

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5
Q

What are corticosteroids

A

Mineralocorticoids (aldesterone)

Glucocorticoids (cortisol)

SEx steroids (androgens, oestrogens)

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6
Q

Where is aldosterone and cortisol found

A

Aldosterone : zona glomerulosa

Cortisol - Zona fasciculata and zona reticularis

1000 times more cortisole than aldesterone

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7
Q

Section of tissue of the adrenal cortex : microanatomy

A
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8
Q

The adrenal cortex microanatomy diagram

A

Blood carries the aldosterone thru vesiculata as it picks up cortisol etc and then will all come out of this vein

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9
Q

What is a steroid

A
  • Comes from cholesterol
  • ADrenal gland secretion precursor is cholesterol
  • Not all are same - may have diff effects
  • cholesterol has 27 C atoms
  • Oxidation of different carbons drives the production of the adrenal hormones
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10
Q

How is aldesterone and cortisol produced by enzyme action on cholesterol

A

ENzymes are hydroxylases

Eg 17 hydroxylase

specific enz catalyse the synthesis of alterations to the molecule

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11
Q

Why may some people not produce enough cortisol

A

Missing enz such as 21 hydroxylase

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12
Q

Aldesterone mechanism of action

A

Kidney takes blood and produces urine

Glomerulus filters urine

Tubules swaps out things you don’t need and things you need

Controlled by aldosterone

Switches on enzymes sodium and potassium atpases

Reabsorb Na+ and water in distal convoluted tubule and corticol collecting duct, and lose K+ and H+ maintaining blood pressure in same areas

Xs K - Potassium is lost in urine

So controls bp, sodium and lowers K

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13
Q

renin relase when blood pressure falls

A

When blood presure falls - produce renin

Goes into circulation

Switches on cascade

Liver makes basic protein

If there is decreased renal perfusion pressure (decreased arterial BP)

=> Increased renal sympathetiv actvity

(direct to JGA cells)

=> Decreased Na+ load to top of loop of Henle

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14
Q

Renin stimulates activation

A
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15
Q

Effects of angiotensin II on adrenals

A

Angiotensin II stimulates aldosterone production in the zona glomerulosa in the adrenal medulla

Side chain cleavage

activates enzymes for production of aldosterone (3-hyroxysteroid dehydrogenase; 21, 11, 18 hydroxylases)

Cholesterol initiates chain reaction switching on enz - happens when you see more angiotensin II

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16
Q

Physiological effects of cortisol

A

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

When there is too much cortisol, negative feedback suppression of CRH and ACTH

Cortisol changes way you use energy - makes you break down protein - converted to glucose to keep you alive - blood gluc increase, breaks up fat locally

17
Q

Adenohypophysis feedback

A
18
Q

Effects of ACTH on adrenals

A

ACtivates same enz as angiotensin execept 18 hydro - replaced with 17 hydroxylase

19
Q

Cortisol has …. rhythm

A

diurnal circadian rhythm

It is low at midnight

20
Q

Addisons disease

A
  • Primary adrenal failure
  • Autoimmune disease where the immune system destroys the adrenal cortex
  • Tuberculosis of the adrenal gland
  • Pituitary starts secreting loads of ACTH and thus MSH
  • Increased pigmintation
  • Autoimmune vitilligo
  • No cortisol or aldosterone so low BP
  • Cortisol deficiency
  • Aldosterone deficiency
  • Salt loss
  • Low blood pressure
  • Eventual death
21
Q

Why do patients with addisons have a good tan

A

The pigmentation is caused by increased levels of MSH which comes hand in hand with increased ACTH

Both ACTH and MSH and endorphins come from the large precursor protein Pro-opio-melanocortin (POMC) which is broken down to form many smaller hormones

HIgh level of ACTH - increased MSH - stimulates skin cells to freckle and then tan

22
Q

Summary of addisons

A

cortisol deficiency

Aldosterone deficiency

salt loss

Low bp

Eventual death

23
Q

Treatment of Addisonian crisis

A

Rehydrate with normal saline

Give dextrose to prevent hypoglycaemia which could be due to the glucocorticoid deficiency

Give hydrocortisone or another glucocorticoid

24
Q

What is cushings syndrome

A

too much cortisol (or other glucocorticoid) caused by a tumour of the adrenal gland of tumour of pituitary (excess ACTH)

25
Q

Symptoms of cushings

A

Thin skin

Proximal myopathy

Centripetal obesity (lemon on sticks) (thin legs and arms but obesity)

Diabetes, hypertension and osteoporosis

Immunosuppression (reactivation of TB)

Moon face

Red Striae (stretch marks - body cant make protein fast enough for fat deposition)

Easy bruising

Depression

POor wound healing

Fat pads (because tumour makes ACTH continuosly - adrenal gland gets bigger - cortisol gets around body - fat pads develop)

26
Q

What causes cushings

A
  • Xs of cortisol or other glucocorticoid
  • Taking steroids
  • Pituitary adenoma
  • Ectopic ACTH (lung cancer) (can express random genes and so too much cortisol may be produced)
  • Adrenal tumour
27
Q

what are catecholamines

A

Adrenal hormones

Medulla is derives from the ectodermal neural crest

Tyrosine is the precursor for Adr and NA synthesis

Catecholamines are stored in cytoplasmic granules & are released in response to Ach fom preganglionic sympathetic neurones

Dop secreted rapidly

28
Q

role of catecholamines

A

‘Fight or flight response’ e.g. tachycardia, sweating, increased blood glucose, alertness, vasoconstriction

NA & Adr circulate bound to albumin

Degraded by two hepatic enzymes: monoamine oxidase & catechol-O-methyl transferase

29
Q

The adrenal gland

A
30
Q

Microanatomy pic

A
31
Q

Hpa axis pic

A

ENDOCRINOLOGY (5 decks)

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