Endocrine Pancreas

Question 1

what is secreted in response to CHO- and/or protein ingestion?

Answer 1

insulin

Question 2

what is the major stimulatory factor of insulin secretion?

Answer 2

glucose

Question 3

what do the endocrine cells of the pancreas secrete?

Answer 3

insulin, glucagon, and somatostatin

Question 4

how are the endocrine cells of the pancreas arranged?

Answer 4

in clusters known as islets of langerhans

Question 5

what are the endocrine cells of the pancreas?

Answer 5

beta-cells, alpha-cells, delta-cells, and F-cells

Question 6

what do the beta cells secrete?

Answer 6

insulin and C peptide

Question 7

what do the alpha-cells secrete?

Answer 7

glucagon

Question 8

what do the delta-cells secrete?

Answer 8

somatostatin

Question 9

what do the F cells secrete?

Answer 9

pancreatic polypeptide

Question 10

which cells are destroyed in a type 1 diabetic?

Answer 10

beta cells

Question 11

what is the role of the F cells and their secretions?

Answer 11

they act like a satiety signal (neuropeptide Y, peptide YY family)

Question 12

how do the endocrine cells of the pancreas/islets communicate with each other?

Answer 12

via gap junctions and blood supply

Question 13

how does the arterial supply come into the islets?

Answer 13

it comes into the center and is going to primarily bathe the beta-cells

Question 14

what kind of hormone is insulin?

Answer 14

peptide hormone

Question 15

what is secreted at the same time as insulin?

Answer 15

C peptide

Question 16

what does insulin signal the liver to do?

Answer 16

the liver senses the insulin and will stop producing glucose out into the bloodstream

Question 17

how does glucose enter the beta-cell?

Answer 17

via GLUT-2

Question 18

what happens once glucose enters the beta-cell?

Answer 18

it is phosphorylated by glucokinase into glucose-6-phosphate

Question 19

what happens to the glucose-6-phosphate?

Answer 19

it is oxidized, which promotes ATP generation

Question 20

what effect do the rising ATP levels have in the beta-cell?

Answer 20

ATP closes the “inward-rectifying” K+ channel (so the plasma membrane is a little more positive on the interior)

Question 21

what happens when the inward rectifying K+ channels are closed?

Answer 21

the plasma membrane is a little more positive on the interior–> the plasma membrane is depolarized

Question 22

what happens when the plasma membrane of the beta-cells is depolarized?

Answer 22

there is activation of the voltage-gated Ca2+ channels and Ca2+ enters the cell

Question 23

what happens when Ca2+ enters the beta-cells?

Answer 23

it initiates mobilization of insulin and C peptide containing vesicles to plasma membrane and exocytosis

Question 24

what drugs target the ATP-dependent K+ channels to increase insulin secretion?

Answer 24

sulfonylurea receptor drugs

Question 25

what is a general characteristic of insulin release?

Answer 25

it is biphasic- there is an initial spike within minutes and a further increase half an hour to an hour later

Question 26

what phase of insulin secretion is lost first in type 2 diabetics?

Answer 26

the first phase

Question 27

where does insulin resistance primarily occur?

Answer 27

adipose tissue and skeletal muscle

Question 28

what happens through AKT?

Answer 28

it signals to vesicles containing GLUT-4 to move to the plasma membrane and insert the GLUT-4 into the membrane. It then allows glucose to move into the cell, which will in turn lower the blood glucose levels

Question 29

what is a hypothesis on why the intracellular signaling gets "mucked up"?

Answer 29

mitochondrial overload- they have byproducts of metabolism that cause of family of stress kinases to inhibit and block what this intracellular signaling should do

Question 30

what happens to the incretin effect in T2DM?

Answer 30

it is abolished

Question 31

what are the stimulatory factors of insulin secretion?

Answer 31

increased glucose/amino acid/fatty acid/ketoacid concentration, glucagon, cortisol, GIP, CCK, GLP-1, vagal stimulation (ACh), sulfonylurea drugs

Question 32

what are the inhibitory factors of insulin secretion?

Answer 32

fasting, exercise, somatostatin, norepinephrine, diazoxide

Question 33

what effect does insulin have on K+?

Answer 33

there is an increased K+ uptake into the cells and therefore decreased K+ in the blood level

Question 34

what does muscle contraction activate?

Answer 34

AMP-Kinase (AMPK), which results in GLUT4 translocation to the plasma membrane and then glucose uptake

Question 35

what is the effect of glucagon?

Answer 35

it increases blood glucose levels

Question 36

what is the secretion of glucagon stimulated by?

Answer 36

decreased blood glucose (major), increased AAs, fasting, B-adrenergic agonists, ACh

Question 37

what inhibits glucagon?

Answer 37

insulin and high blood glucose levels and somatostatin

Question 38

what is the major factor contributing to development of T2DM?

Answer 38

multiple genes coupled with environment

Question 39

what ethnic group is more at risk for developing T2DM?

Answer 39

african americans, hispanic, and Pima native americans

Question 40

what happens when adipose tissue becomes inflammed?

Answer 40

they recruit macrophages, which then tell the adipocytes to become more dysfunctional and start releasing more inflammatory factors

Question 41

what are some pro-inflammatory cytokines?

Answer 41

IL-6, TNF-alpha, CRP

Question 42

what is the step after systemic insulin resistance?

Answer 42

reactive hyperinsulinemia- after eating a meal, glucose levels are normal but more insulin required

Question 43

what happens after hyperinsulinemia?

Answer 43

postprandial hyperglycemia

Question 44

when do symptoms become evident of T1DM?

Answer 44

not until ~80% of Beta cells are destroyed

Question 45

how do you get diabetic ketoacidosis (DKA)?

Answer 45

if there is decreased utilization of ketoacids

Question 46

besides inadequate insulin secretion, what else happens in T1DM patients?

Answer 46

hyperkalemia and osmotic diuresis

Question 47

is a family history more prominent for type 1 or type 2 diabetes?

Answer 47

type 2

Question 48

what is an example of a gene that is predominantly mutated in cases of T1DM?

Answer 48

DQ2/DQ8 gene