Physio of the Adrenal Cortex

Question 1

What are glucocorticoids predominantly prescribed for?

Answer 1

Anti-inflammatory/immunosuppressive agents
Effects leukocyte movement and function, decrease migration of inflammatory cells to the site of the injury, decreases prostaglandin production

Question 2

Adrenal gland structure

Answer 2

Cortex and medulla

Cortex has 3 layers” zona glomerulosa, zona fasiculata, zona reticularis

Question 3

What does each layer of the adrenal cortex produce?

What does the medulla produce?

Answer 3

Glomerulosa: mineralocorticoids (aldosterone)
Fasiculata: Glucocorticoids (cortisol)
Reticularis: androgens
Medulla: catecholamines

Question 4

Cholesterol for steroid hormone biosynthesis comes from what 2 souces

Answer 4

Circulating cholesterol (major source)
De novo synthesis from acetate

Question 5

Why can’t cells of the zona glomerulosa make cortisol or androgens?

Answer 5

Do not express 17a hydroxylase

Question 6

Why can’t cells of the zona fasiculata and reticularis make aldosterone?

Answer 6

Do not express aldosterone synthase

Question 7

What type of receptors do steroids have?

Answer 7

Nuclear receptors
They are lipid soluble so their receptors are intracellular
Bind to a hormone response element on DNA and cause gene transcription

Question 8

How are steroid hormones metabolized

Answer 8

Inactivation mainly occurs in the liver, but also in the target tissues and kidney
Get converted to hydrophilic compounds
Eliminated as urinary metabolites (not recycled)

Question 9

Aldosterone function

Answer 9

Binds to the mineralocorticoid receptor to regulate gene expression and induce rapid effects via non genomic mechanisms
Regulates reabsorption of Na and secretion to K to maintain blood volume and BP
Production is stimulated by AII

Question 10

Functions of aldosterone

1. Rapid effects
2. Slower responses

Answer 10

1. Increased Na channel activity in CT and DCT (increasing availability/opening channels)
2. Upregulation of genes for Na channels, Na/K pumps, and kinases

Question 11

ACTH acts on the cells of the adrenal cortex by what receptor?

Answer 11

Melanocortin-2 receptor

Question 12

ACTH action

Answer 12

Increases steroidogenesis
Maintains adrenocortical cells
Regulates adrenal androgen secretion

Question 13

What is the inactive form of cortisol?

Answer 13

Cortisone

Question 14

Does D1 or D2 enzyme activate or inactive cortisol?

Answer 14

D1: converts inactive to active (liver)
D2: converts active to inactive (kidney)

Question 15

Glucocorticoid effects on the

1. Liver
2. Muscle
3. Adipose tissue

Answer 15

Maintenance of blood glucose levels

1. Increased hepatic glucose production (gluconeogenesis, glycogen deposition)
2. Decreased glucose uptake, catabolism of protein
3. Lipolysis is stimulated