Carbohydrate Metabolism

Question 1

How many islets per pancreas?

Answer 1

1 million

Question 2

What percent of pancreas is islets?

Answer 2

1-2%

Question 3

What percentage of islets are beta cells?

Answer 3

60%

Question 4

What percentage of islets are alpha cells?

Answer 4

25%

Question 5

Blood flow through islets?

Answer 5

Fenestrated capillaries support flow from central core to periphery where it empties into poral

Question 6

Physiology of biphasic insulin secretion?

Answer 6

Initial stimulation causes release of docked secretory granules. Second phase is result of non-docked vesicles moving up

Question 7

Stimulants for insulin release

Answer 7

Glucose, Amino Acids, Acetylcholine (Vagus)

NOT FAT

Question 8

Inhibitors of insulin secretion

Answer 8

SST (delta cells), catecholamines, splanchnic nerves

Question 9

Structure of insulin receptor

Answer 9

Heterotetramer of 2 alpha and 2 beta subunits

Question 10

Function of insulin receptor

Answer 10

tyrosine kinase, autophosphorylates and phosphorylates SH2 domains, specially IRS

Question 11

2 types of insulin signaling

Answer 11

Metabolic (PI3K, AKT) and Mitogenic (MAPK)

Question 12

Possible cause of insulin resistance at the receptor level?

Answer 12

Increased phosphorylation of serine and threonine residues, making tyrosine phosphorylation harder