Endocrine pancreas and Glucose homeostasis

Question 1

what are islets of Langerhans

Answer 1

clusters of ~1000 endocrine cells

Question 2

how many islets of Langerhans are there in a human pancreas

Answer 2

1 million

only 1-2% of pancreatic volume

Question 3

what are the different islet endocrine cell types

Answer 3

alpha-cells, beta-cells, delta-cells, PP-cells, epsilon-cell

Question 4

what do alpha-cells in islet of Langerhans secrete

Answer 4

glucagon

Question 5

what do beta-cells in islet of Langerhans secret

Answer 5

insulin

Question 6

what do delta-cells in islet of Langerhans secret

Answer 6

somatostatin

Question 7

what do PP-cells and epsilon-cells in islet of Langerhans secrete

Answer 7

PP-cells secrete pancreatic polypeptides

epsilon-cells secrete Ghrelin

Question 8

what proportion of islet of Langerhans are each type of cell

Answer 8

beta-cells 55%, alpha-cells 38%, delta-cells <5%, PP-cells ~1%

Question 9

what effect does fasting/exercise have on normoglycaemia

Answer 9

hypoglycaemia

Question 10

what is the physiological response to hypoglycaemia and what does it result in

Answer 10

decrease insulin, increase glucagon

results in glucose production

Question 11

what is the physiological response to hyperglycaemia and what does it result in

Answer 11

increase insulin, decrease glucagon

results in glycogen synthesis

Question 12

what effect does feeding have on normoglycaemia

Answer 12

hyperglycaemia

Question 13

how is lipid homeostasis affected by hypo- and hyperglycaemia

Answer 13

hypoglycaemia = hypolipidaemia
hyperglycaemia = hyperlipidaemia

Question 14

how is lipid homeostasis affected by glucose production and glucose storage

Answer 14

glucose storage = lipid storage

glucose production = lipolysis

Question 15

what does the beta-cell do in glucose homeostasis

Answer 15

beta-cell compensation

Question 16

what does the beta-cell do in hyperglycaemia

Answer 16

beta-cell defected, relative to insulin demand

Question 17

how does blood glucose affect glucagon secretion from alpha-cells

Answer 17

glucagon secretion inversely proportional to blood glucose

Question 18

what effect does glucagon have on the liver

Answer 18

promotes hepatic glucose production, raising blood glucose

Question 19

what happens to glucagon in T2DM

Answer 19

glucagon secretion is elevated in fed state, contributes to hyperglycaemia