Adrenal Glands

Question 1

Adrenal gland anatomy?

Answer 1

Sit atop kidneys, Left Adrenal Vein drains into Renal Vein, Right Adrenal Vein drains into IVC, many arteries supply adrenal glands (Superior, Middle, Inferior Suprarenal arteries)

Question 2

Microanatomy?

Answer 2

Adrenal Cortex: Zona Glomerulosa, Z. Fasciculata, Z. Reticularis, Adrenal Medulla

Question 3

Adrenal hormones?

Answer 3

Cortex (corticosteroids): Z. Glomerulosa -> Mineralocorticoid (ALDOSTERONE); Z. Fasciculata -> Glucocorticoid (CORTISOL) + some ANDROGENS
Medulla: catecholamines (ADRENALINE, NORADRENALINE)

Question 4

what is a steroid?

Answer 4

molecule formed from cholesterol

Question 5

Synthesis of Aldosterone?

Answer 5

Cholesterol (Side Chain Cleavage) → Pregnenolone (3 beta HydroxySteroid Dehydrogenase) → Progesterone (21 hydroxylase) → 11-deoxycorticosterone (11 H) → corticosterone (18 H) → ALDOSTERONE

Question 6

Synthesis of Cortisol?

Answer 6

Cholesterol (Side Chain Cleavage) → Pregnenolone (3 beta HydroxySteroid Dehydrogenase) → Progesterone (17 Hydroxylase) → 17-hydroxyprogesterone (21 H) → 11-deoxycortisol (11 H) → CORTISOL

Question 7

Aldosterone function?

Answer 7

Aldosterone acts on nuclear receptor in DCT/Collecting Duct cells → stimulates reabsorption of Na+ and secretion of K+ and H+ → Na+ reabsorption stimulates water reabsorption due to osmotic gradient ∴ ↑blood volume {controls BP, Na+; ↓K+}

Question 8

Aldosterone regulation?

Answer 8

Renin-Angiotensin system: ↓renal perfusion pressure stimulates increased renal sympathetic activity in JGA cells/ ↑ Na+ delivery to Macula Densa cells → increased RENIN production
RENIN converts Angiotensinogen (produced in liver) to Angiotensin 1 (Angiotensin Converting Enzyme ACE) → Angiotensin 2 → stimulates Aldosterone production + vasoconstriction

Question 9

Angiotensin 2 function?

Answer 9

stimulates activation of enzymes required in zone glomerulosa: SAC; 3beta HSD; 21, 11, 18 hydroxylases

Question 10

Cortisol Function?

Answer 10

normal stress response; metabolic effects: ↑hepatic gluconeogenesis, lipolysis, protein catabolism, potentiates effect of Glucagon, Catecholamines; weak mineralocorticoid effects; excretion of water load, ↑vascular permeability

Question 11

Cortisol Regulation?

Answer 11

ACTH stimulates activation of enzymes in Z. Fasciculata: SAC; 3beta HSD; 17, 21, 11 hydroxylases; cortisol -> -ve feedback loop on HPA axis; diurnal rhythm which follows circadian rhythm

Question 12

Addison’s Disease?

Answer 12

Primary Adrenal Failure: usually caused by autoimmune damage/TB damage

Question 13

Feature of Addison’s disease?

Answer 13

hypocortisolism → ↑ACTH + MSH secretion; Pro-opiomelanocortin -> large precursor protein; ↑MSH leads to skin hyperpigmentation (TAN)

Question 14

Addison’s Disease S&S?

Answer 14

Skin+mucosa hyperpigmentation, vitiligo; GI: weight loss, nausea, diarrhoea, vomiting, constipation; hypotension, weakness

Question 15

Adrenal Crisis S&S?

Answer 15

fever, syncope, convulsions, hypoglycaemia, hyponatraemia, severe vomiting/diarrhoea

Question 16

Adrenal Crisis treatment?

Answer 16

normal saline -> fluid rehydration; DEXTROSE to prevent hypoglycaemia; HYDROCORTISONE/other Glucocorticoid

Question 17

Cushing’s Syndrome features?

Answer 17

Hypercortisolism (adrenal tumour)/↑ACTH (pituitary tumour)

Question 18

Cushing’s causes?

Answer 18

1 - excess PO steroid ingestion; 2 - pituitary dependent Cushing’s disease (pituitary adenoma); 3 - ectopic ACTH (lung cancer); 4 - adrenal adenoma/carcinoma

Question 19

Cushing’s S&S?

Answer 19

thin skin, central obesity, purple striae; diabetes, hypertension, osteoporosis; Red Moon Face; proximal myopathy; inter scapular fat pads (buffalo humps)

Question 20

Catecholamines? release?

Answer 20

synthesised in medulla from tyrosine → DOPA → dopamine → Noradrenaline → Adrenaline; stored in cytoplasmic granules -> released in response to ACh in pregranglionic sympathetic neurons

Question 21

Catecholamine function?

Answer 21

involved in Fight or Flight response -> tachycardia, sweating, ↑ blood glucose, alertness, vasoconstriction

Question 22

Catecholamine transport & degradation?

Answer 22

circulate bound to Albumin; degraded by 2 hepatic enzymes: monoamine oxidase, catechol-3-O-methyl transferase