Adrenal Medulla

Question 1

Steps in catecholamine synthesis

Answer 1

Liver
1. Phenylalanine oxidized to Tyrosine
Adrenal gland
2. Tyrosine oxidized to Dihydroxyphenylalanine [DOPA] (ACTH promotes via cAMP)
3. DOPA decarboxylated to Dopamine
4. Dopamine oxidized to Norepinephrine via Dopamine B-hydroxylase [Vit C facilitates] (ACTH promotes)
5. NE methylated to Epi via PNMT [SAM donates methyl] (ACTH promotes INDIRECTLY via Cortisol)

Question 2

Release of catecholamines into the bloodstream is stimulated by:

Answer 2

Ach and calcium

Question 3

Where are MAO and COMT found?

Answer 3

Neural tissue (MAO-A)
Liver and Kidneys (MAO-B)

Question 4

Function of MAO

Answer 4

Remove NH2 or NHCH3 group

Question 5

Function of COMT

Answer 5

Add methyl group (from SAM) to hydroxyl

Question 6

Catecholamine degradative reactions

Answer 6

Just COMT -> (Nor)METAnephrine

COMT + MAO ->
VMA&raquo_space; MOPEG

All leave via urine

Question 7

What are the three diabetogenic hormones and what do they do?

Answer 7

1. GH
2. Cortisol
3. Glucagon

Increase blood glucose

Question 8

a1 responds to which catecholamines through which mechanism?

Answer 8

N > E

Calcium increase

Question 9

a2 responds to which catecholamines through which mechanism?

Answer 9

N > E

Decreased AC

Question 10

B receptors respond to which catecholamines through which mechanism?

Answer 10

B1 : both equally
B2/3: E>N

Increased AC

Question 11

Effects of catecholamines

Answer 11

1. Increase blood glucose
via gluconeogensis (like cortisol)
and glycogenolysis (unlike cortisol)
2. Increase lipolysis
3. Increase CO
4. Increase glucagon/decrease insulin
5. Increase Renin
6. Relax bronchiolar smooth muscle
7. Increase potassium uptake

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Glucagon, Relax bronchioles, Lipolysis, Renin, Blood glucose, Potassium, Cardiac output

Question 12

Effect of catecholamine binding B1

Answer 12

Increased inotropy/chronotropy

Question 13

Effect of catecholamine binding a1

Answer 13

Vasoconstriction (i.e. most tissues)

Question 14

Effect of catecholamine binding B2

Answer 14

Vasodilation (i.e. skeletal muscle)

Question 15

Three hormones that remove XS potassium via Na/K-ATPase

Answer 15

1. Epinephrine (exercise; skeletal muscle/B2 receptors)
2. Aldosterone (into skeletal muscle or out through urine)
3. Insulin (ingestion; skeletal muscle and liver)

Question 16

3 Phases of Trauma

Answer 16

1. Defense against volume depletion
   a. RAAS (JG cells)
   b. ADH
   c. Catecholamines
   d. Cortisol
2. Catabolic
   a. Cortisol, thyroxine, and catecholamines
   b. Glucagon
3. Anabolic
   a. Insulin
   b. GH
   c. Erythropoietin
   d. Thyroxine

*Notice that thyroxine is increased in both the catabolic and anabolic phases