Lecture 16- The Adrenal Glands

Question 1

Adrenal gland structure?

Answer 1

Cortex which produces mineralcorticoids like aldosterone and glucocorticoids like cortisol and also androgens

Medulla with chrimaffin cells which produce adrenaline and noradrenaline

Question 2

Mineralcorticoids vs glucocorticoids?

Answer 2

Mineralcorticoids affect salt and water balance. Glucocorticoids work against inflammation etc

Question 3

Steroid hormones?

Answer 3

Made from cholesterol . Lipid soluble. Act on intracellular receptors and affect gene transcription

Question 4

Aldosterone?

Answer 4

Mineralcorticoids produced by Dona glomerulosa in adrenal cortex. Lipophilic steroid hormone acts at intracellular receptors. Alters gene transcription. Central part of RAAS system regulates blood pressure by increasing water absorption in nephron though sodium potassium transporters

Question 5

How does the RAAS system work?

Answer 5

Low blood pressure detected by juxtaglomerular apparatus of kidney. Triggers renin production which cleaves angiotensinogrn produced by liver into angiotensin 1 which is converted by ACE into angiotensin 2 which causes vasoconstriction of vessels. Activates aldosterone secretion from adrenal cortex and causes ADH secretion from pituitaries. Causes translocation of aquaporin channels in nephron and increased potassium sodium pump expression causes increased water reabsorption and increased blood pressure

Question 6

Hyperaldosteronism causes?

Answer 6

Primary- defect in adrenal cortex. Can be caused by bilateral idiopathic hyperplasia and conns syndrome which is a aldosterone secreting adrenal adenoma. Results in high aldosterone and low renin as adrenal cortex secreting aldosterone regardless of action of renin.

Secondary cause is overactivation of RAAS pathway. Renin producing tumour or renal stenotic artery causes hypoperfusion and renin secretion. Results in high renin with low aldosterone ratio

Question 7

Signs of hyperaldosteronism?

Answer 7

High blood pressure
Hypernatraenia and hypokalaemia

Left ventricular hypertrophy
Stroke

Question 8

How to treat hyperaldosteronism?

Answer 8

Remove adenoma producing aldosterone

Give spirolactone which is a mineralcorticoids receptor antagonist (also used to treat high BP)

Question 9

Cortisol?

Answer 9

Released fromzone fasiculata in adrenal cortex. Transported by transcortin. Acts intracellularly by regulating gene transcription. Has catabolic effects like proteolysis, lipolysis and gluconeogenesis. Stress resistance through increasing blood glucose and causing vasoconstriction. Anti inflammatory effects so used for allergies and also to depress immune system after organ transplant

Question 10

What stresses would cause cortisol secretion?

Answer 10

Low BP
Hypoglycaemia
Fever
Pain

Question 11

Hypothalamic-pituitary adrenal axis?

Answer 11

Hypothalamus produced CRH which acts on anterior pituitary which releases ACTH which acts in adrenals to release cortisol

Question 12

Glucocorticoid metabolic effects?

Answer 12

Redistribution of fat (buffalo hump)

Breakdown of protein

Increased glucose production and prevention of uptake

Question 13

Cushing’s syndrome?

Answer 13

External causes (common) are prescribed glucocorticoids which raise cortisol

Rare causes are cushings disease where you get pituitary adenoma secreting ACTH

Adrenal tumour which is adrenal cushings and non pituitary or adrenal tumours that produce ACTH

Question 14

Steroid drugs examples?

Answer 14

Prednisone needs and dexamethasone

Similar effects at high concentration as cortisol. Used to suppress immune system following organ transplantation and treat inflammatory disease like asthma and IBD

Question 15

What is Addison’s disease?

Answer 15

Chronic adrenal insufficiency opposit of cushings

Caused by autoimmune response

Effects include hypoglycaemia, postural hypotension,weight loss and skin pigmentation

Question 16

Why hyperpigmentation in addisons?

Answer 16

Decreased cortisol means more ACTH must be produced. This requires more POMC but POMC also makes MSH which results in increased melanin synthesis

Question 17

Addisonian crisis?

Answer 17

Life threatening precipitated by stresses such as cold, stress, trauma, infection and over exertion

Symptoms include nausea, vomiting, hypotension

Treat with cortisol and fluid replacement

Question 18

Androgens?

Answer 18

From zone reticularis of adrenal cortex.

Converted to testosterone and oestrogen

Promote auxiliary and pubic hair growth in both sexes

Question 19

How is adrenaline made?

Answer 19

Tyrosine to levodopa to dopamine to noradrenaline to adrenaline

Question 20

Where is adrenaline and noradrenaline made?

Answer 20

In the chromaffin cells oft the adrenal medulla .release 80% adrenaline 20% noradrenaline

Question 21

Adrenergic receptors?

Answer 21

QISS

Adenylyl cyclase to cAMP to protein kinase A to target proteins

Phospholipase c to IP3 and DAG to protein kinase C and IP3 receptor

Question 22

Hormonal actions of adrenalin?

Answer 22

Heart rate and contractility increased by beta 1

Bronchidilation beta 2

Vasoconstriction to skin and gut alpha 1

Vasodilation to skeletal muscle beta 2

Question 23

What is a phaeochromocytoma?

Answer 23

Chromaffin cell tumour

Can cause life threatening hypertension

Headaches 
High BP
Palpitations 
Anxiety
Weight loss
High blood glucose