Adrenal Physiology

Question 1

What are the three zones of the human adrenal gland?

Answer 1

Zona Fasciculata
Zona Glomerulosa
Zona Reticularis

Question 2

What is the function of the Zona Fasciculata and Zona Reticularis?

Answer 2

Produce glucocorticoids, cortisol, sex steroids and androgens under feedback from the hypothalmic-pituitary-adrenal axis

Question 3

What is the function of the Zona Glomerulosa?

Answer 3

Secretes aldosterone under the control of the renin-angiotensin system

Question 4

What is the function of the adrenal medulla?

Answer 4

Synthesizes, stores and secretes catecholamines

Question 5

What is the molecule that is the basis for all of the corticosteroid hormones?

Answer 5

Cholesterol

Question 6

What family of hormones is responsible for the conversion of cholesterol to the corticosteroid hormones?

Answer 6

Cytochrome p450 family

Question 7

What is the hypothalmic-pituitary-adrenal axis?

Answer 7

1. Various factors e.g. stress, illness, time of day cause the HYPOTHALAMUS to secrete corticotropin releasing hormone.
2. This causes the ANTERIOR PITUITARY to secrete adrenocorticotrophic hormone.
3. This causes the ADRENAL CORTEX to release cortisol.
4. Cortisol acts in a negative feedback loop on the hypothalamus and the pituitary

Question 8

What is the regulation of the renin-angiotensin system?

Answer 8

1. This is activated in response to a drop in blood pressure which causes the kidneys to release renin.
2. This leads to production of angiotensin II which causes direct vasoconstriction and indirect aldosterone release. This acts to increase BP.

Question 9

What are the six classes of steroid receptor?

Answer 9

Glucocorticoid
Mineralocorticoid
Progestin
Oestrogen
Androgen
Vitamin D

Question 10

What is the mechanism of action of corticosteroids?

Answer 10

They bind to intracellular receptors. The receptor ligand complex then binds to DNA to affect transcription.

Question 11

What are the major actions of cortisol?

Answer 11

Circulatory/Renal - Increase CO, BP, renal blood flow and GFR
CNS - Decreases libido, induces euphoria, mood liability
Bone/Connective Tissue - Accelerates osteoporosis, reduces serum calcium, collagen formation, and wound healing
Immunological - Reduces capillary dilatation, leukocyte migration, macrophage activity, inflammatory cytokine production
Metabolic - Increases blood sugar, lipolysis, proteolysis and central redistribution

Question 12

What are the three principle uses of corticosteroid treatment?

Answer 12

Suppress inflammation
Suppress immune system
Replacement therapy

Question 13

What diseases are treated with corticosteroids?

Answer 13

Allergic disease - asthma and anaphylaxis
Inflammatory disease - rheumatoid disease, ulcerative colitis, crohn’s disease
Malignant disease

Question 14

What are the actions of aldosterone?

Answer 14

Sodium Potassium Balance - K+/H+ excretion; Increased Na+ reabsorption
Blood Pressure Regulation
Regulation of Extracellular Volume

Question 15

What is the location of the mineralocorticoid receptors?

Answer 15

Kidneys
Salivary Glands
Gut
Sweat Glands