Adrenal physiology

Question 1

What is the function of 17a-hydroxylase?

Answer 1

1. Converts pregnenolone into androgens 1. Converts progesterone into cortisol

Question 2

What is the function of 3B-hydroxysteroid DH?

Answer 2

1. Converts pregnenolone into progesterone (and then aldosterone) 2. Converts 17-OH progesterone into cortisol

Question 3

What is the function of 21-hydroxylase?

Answer 3

1. Converts progesterone into aldosterone 2. Converts 17-OH progesterone into cortisol

Question 4

What is the function of 11B-hydroxylase?

Answer 4

1. Converts DOC (from progesterone) into aldosterone 2. Converts 11-deoxycortisol into cortisol

Question 5

How does ACTH increase adrenal steroid synthesis?

Answer 5

1. Stimulation of melanocortin-2 receptors on adrenocortical cells 2. Increased import of cholesterol 3. Increased transcription of cholesterol side chain cleavage enzyme and other enzymes involved in steroid synthesis

Question 6

What are the effects of cortisol?

Answer 6

1. Increase blood glucose levels 2. Inhibits immune system 3. Decreases fibroblast proliferation - decreased CT 4. Increases bone matrix resorption and calcium excretion

Question 7

What are the effects of aldosterone?

Answer 7

1. Increases sodium and water reabsorption 2. Decreases potassium reabsorption

Question 8

How does cortisol increase plasma glucose levels?

Answer 8

Inhibits insulin stimulated glucose intake in periphery - insulin will not have as much of an effect

Question 9

How does aldosterone increase sodium and water reabsorption?

Answer 9

1. Binds to mineralcorticoid receptor in cytoplasm 2. Increases transcription of genes for ENaC and Na/K ATPase 3. Sodium moves from tubular lumen into cell 4. Na/K ATPase transports sodium into interstitial fluid in exchange for potassium 5. Water follows sodium

Question 10

What are the catecholamines released by the adrenal medulla?

Answer 10

NE and epi

Question 11

How does cortisol regulate epinephrine?

Answer 11

1. Induces expression of epi receptors 2. Increases expression of enzyme that converts NE into epi in adrenal medulla

Question 12

How does cortisol facilitate the effects of NE and epi?

Answer 12

1. Increases glycogen deposition in liver by increasing glycogen synthase and inhibiting glycogen phosphorylase 2. Induces expression of receptors for epi and NE 3. Increases expression of enzyme that converts NE into epi in adrenal medulla

Question 13

What are the causes, symptoms, and pathophysiology of of Cushing’s syndrome?

Answer 13

1. Chronic glucocorticoid (cortisol) excess 2. Hypercortisolism causes hypokalemia and hypertension by binding to aldosterone receptors, increasing effects of epi and NE

Question 14

What are the causes, symptoms, and pathophysiology of Addison disease?

Answer 14

1. Primary adrenal insufficiency 2. Hypotension from unresponsiveness of vascular smooth muscle to catecholamines 3. Hypoglycemia 4. No feedback inhibition of ACTH and CRH (increased levels of both)

Question 15

What are the causes and symptoms of 21-hydroxylase deficiency?

Answer 15

1. Congenital adrenal hyperplasia 2. Buildup of androgens, decrease in aldosterone and cortisol production 3. Hypotension, virilization of females

Question 16

What is the effect of a 17a-hydroxylase deficiency?

Answer 16

Cannot form cortisol or androgens - all products shunted into aldosterone pathway

Question 17

What is the effect of a 3B-hydroxysteroid DH deficiency?

Answer 17

Low aldosterone and cortisol - buildup of DHEA

Question 18

What is the effect of 21-hydroxylase deficiency?

Answer 18

All products shunted into androgen pathway