10-Adrenal glands

Question 1

Structure

Answer 1

5cm wide
On top of kidneys
Consist of capsule, cortex and medulla
Capsule very thin
Zona fasciculata is the largest part of cortex

Question 2

Steroid hormones of the adrenals

Answer 2

Glucocorticoids=cortisol
Mineralcorticoids=aldosterone
Cholesterol is the precursor

Question 3

Genomic mechanism of cortisol

Answer 3

Released in the bloodstream bound to globulin such as albumin
Receptor complexed with HSP
When cortisol binds, HSP displaced
Steroid receptor complex migrates to nucleus
Dissociates rapidly from target gene so limited effect

Question 4

Non-genomic mechanism of cortisol

Answer 4

Rapid response to stress
Binds GPCR with Gs
Activates kinases
Decreased excitability or secretion of ions

Question 5

Release of cortisol

Answer 5

GPCR regulated
Response elements in genes bound to

Question 6

Anti-inflammatory effects of GCs

Answer 6

Stablises lysosomal membranes
Reduce release of proteolytic enzymes

Decreases permeability of capillaries
Reduced oedema

Decreased migration of white blood cells
Reduced prostaglandins, leukotrienes

Suppression of immune system
Reduction in T cells and antibodies

Reduction in fever
Less IL-1

Healing increases
More amino acids, fats and glucose available

Question 7

Metabolic effects of GCs

Answer 7

Indicates to catecholamines to exert lipolytic effects
Glucagon exert calorigenic effects
Increased gluconeogenisis

Question 8

Aldosterone

Answer 8

Retention of salts
Increases blood pressure
Controls absorption and secretion of Na and OKAY

Question 9

Release of aldosterone

Answer 9

Releases in response to increased K in kidney tubules
Increased activity in RAS system
ACTH
Increase in Na in kidney tubule

Question 10

Genomic effects of aldosterone

Answer 10

Similar to GCs

Mainly through increased Na channel proteins and Na-K-ATPase in renal tubular cells
Na channel proteins insertion into luminal side
More limited expression of MC receptors

Question 11

Synthetic steroid GC vs MC activity

Answer 11

Hydrocortisone has equal GC/MC activity
Prednisolone, prednisone – mixed GC/MC activity
Dexamethasone, betamethasone, beclomethasone have pure GC activity
Fludrocortisone has mainly MC activity

Question 12

Crushing’s syndrome

Answer 12

Excessive cortisol release
Tumour of the pituitary or adrenals
GR antagonists used to counteract effects of cortisol
Mifepristone
Also a progesterone receptor antagonist

Question 13

Addison’s disease

Answer 13

Not enough cortisol
Deficiency of the adrenal glands
Not enough ACTH

Hydrocortisone, prednisone or methylprednisoloneare used to replace cortisol

These hormones are given on a schedule to mimic the normal 24-hour fluctuation of cortisol levels

Fludrocortisone acetateto replace aldosterone

Limited side effects as plasma levels mimic natural situation