Adrenal Glands

Question 1

What are the three zones of the cortex and what do they secrete?

Answer 1

Zona glomerulosa - mineralocorticoids Zona fasciculata - glucocorticoids Zona reticularis - androgens

Question 2

What does the medulla secrete?

Answer 2

Adrenaline

Question 3

Describe ACTH

Answer 3

It’s hydrophilic and interacts with high affinity receptors in zona fasciculata and reticularis.

Question 4

Describe what binding of ACTH causes

Answer 4

Binds to melanocortin receptor (corticotrophin) leading to activation of cholesterol esterase.

Question 5

Describe the action of cortisol

Answer 5

Component of stress response. Increases proteolysis, lipolysis and gluconeogenesis.

Question 6

Describe the action of aldosterone

Answer 6

Stimulates Na+ reabsorption in kidney in exchange for K+ (or H+)

Question 7

Describe the action of androgens in males

Answer 7

Stimulate growth and development of male genital tract and secondary sexual characteristics including height, body shape, facial and body hair, lower voice pitch. Also have anabolic actions on muscle proteins

Question 8

What happens if there is over-secretion of androgens in females?

Answer 8

Hirsuitism, acne, menstrual problems, virilisation, increased muscle bulk, deepening voice

Question 9

Describe the effects of oestrogens in females

Answer 9

Stimulate growth and development of female genital tract, breasts and female secondary characteristics including broad hips, accumulation of fat in breasts and buttocks, body hair distribution. Weakly anabolic and decrease circulating cholesterol levels

Question 10

How does adrenaline affect its target cells?

Answer 10

Binds to adrenoreceptors on the outside of the cell activating a secondary messenger

Question 11

How is cortisol secretion controlled by ACTH and CRH?

Answer 11

Question 12

How is adrenaline synthesised?

Answer 12

Tyrosine - dopa - dopamine - noradrenaline - adrenaline

Question 13

List a few of the actions of adrenaline

Answer 13

CVS - increases cardiac output and bloody supply to muscle, CNS - mental alertness, carbohydrate metabolism - glygogenolysis, lipid metabolism - lipolysis

Question 14

What are the clinical implications of over-secretion of adrenaline?

Answer 14

Hypertension, palpitations, sweating, anxiety, pallor and glucose intolerance

Question 15

What is the usual reason for over-secretion of adrenaline?

Answer 15

A tumour (phaemochromocytoma)

Question 16

Explain the mechanism of action of cortisol

Answer 16

Crosses plasma membranes and binds to cytoplasmic receptors. Hormone/receptor complex then changes the rate of transcritption

Question 17

What happens when there is an excess of glucocorticoids secreted?

Answer 17

Cushing’s Syndrome

Question 18

What are the possible causes of Cushing’s Syndrome?

Answer 18

Increased activity of adrenal cortex due to tumour (adenoma), ectopic secretion of ACTH

Question 19

List a few possible signs and symptoms of excess cortisol?

Answer 19

Increased muscle proteolysis and hepatic gluconeogenesis (steroid diabetes), muscle wasting, increased lipogenesis, catabolic effects on proteins etc

Question 20

Give some symptoms of Cushing’s Syndrome

Answer 20

Moon-shape face, weight gain, immunosuppressive response - increased acne and bacterial infections, purple striae

Question 21

What are the possible causes for Addison’s Disease?

Answer 21

Diseases of adrenal cortex reducing glucocorticoids and mineralocorticoids, decreased secretion of ACTH or CRH

Question 22

Describe Addison’s Disease

Answer 22

Insidious onset, increased pigmentation, points of friction, buccal mucosa, decreased blood pressure, postural hypotension

Question 23

What is an Addisonian Crisis

Answer 23

Nausea, vomiting, exterme dehydration, hypotension, confusion, fever and even coma

Question 24

Describe the high dose dexamethasone suppression test

Answer 24

If the tumour is in the pituitary gland then ACTH and cortisol will decrease, if it’s ectopic then ACTH and cortisol will remain elevated despite the dexamethasone

Question 25

Describe the syncathen test

Answer 25

Normally increases plasma cortisol - normal response usually excludes Addison’s Disease

Question 26

Distinguish between Cushing’s Disease and Cushing’s Syndrome

Answer 26

Cushings Disease - Increased secretion of ACTH from pituitary

Cushing’s Syndrome - Hypercortisolism

Question 27

How is it possible for cortisol to bind to mineralocorticoid and angroden receptors?

Answer 27

They have three main regions (hydrophobic hormone binding region, DNA-binding region and a variable region) - sequence homology