pancreatic hormones

Question 1

describe the cell types found in pancreatic islets and their specific hormone they secrete

Answer 1

• alpha cell = glucagon and proglucagon
• beta cell - insulin, C-peptide, proinsulin, IAPP, GABA
• Delta Cells = somatostatin
• Epsilon cells = ghrelin
• PP or F cells = pancreatic polypeptide

Question 2

describe glucose on insulin release

Answer 2

• most potent stimulator of insulin release
• Increases intracellullar ATP –> causes inhibition of K channel leading to depolarization of the membrane
• results in Ca influx and that triggers release of insulin containing vesicles

Question 3

describe vagal stimualtion on insulin release

Answer 3

• acetylcholine activates M3 receptors and increases intracellular Ca
• causes the release of insulin

Question 4

describe GLP1 and Somatostatin effects on insulin release

Answer 4

• Glucagon-like peptide (GLP1) amplifies insulin release

- somatostatin can INHIBIT insulin release

Question 5

describe catecholamines on insulin release

Answer 5

• beta adrenergic stim (epineprhine) amplifies secretion

- alpha-adrenergic stimulation can INHIbIT insulin release

Question 6

describe the cellular events that take palce during glucose and acetylcholine stimulated insulin secretion

Answer 6

• glucose moves down conc gradient into cell (likely thru glucose transporter 2) –> leads to increase ATP in cell
• Increase ATP inhibits K channels causing membrane to depolarize and allowing Ca to flow in
• Ca influx leads to insulin release

Question 7

What are the cellular consequences taht occur following activation of insulin receptors

Answer 7

• broadly activates intracellular signaling pathways

- outcomes are mitogenic (cellular growth) and metabolic

Question 8

what are the metabolic consequences of insulin on the liver

Answer 8

• promotes anabolism = glycogen synth/storage
• inhibits glycogen breakdown
• increases protein, and triglyceride synth
• inhibits catabolism (inhibits glycogenolysis, ketogenesis and gluconeogenesis)

Question 9

what are the metabolic consequences of insulin on adipose tissue

Answer 9

• increases triglyceride storage by promoting free FA uptake, promote esterification of free FAs and inhibits lipolysis

Question 10

what are the metabolic consequences of insulin on skeletal muscle

Answer 10

• increase protein synth by increasing AA uptake
• increases glycogen synth by increasing glucose uptake
• increasing glycogen synthase activity
• inhibiting glycogen phosphorylase

Question 11

Where can you find Glut 4 receptors

Answer 11

• skeletal muscle, adipose tissue

- insulin mediated uptake of glucose

Question 12

where can you find Glut 2 receptors

Answer 12

• pancreatic B-cells, liver/kidney/gut

- leads to insulin release

Question 13

what are the regulators of glucagon secretion

Answer 13

• glucagon has opposite effects of insulin and produced by alpha cells in the gut
• Glucose INHIBITS glucagon secretion
• FA INHIBIT glucagon release
• Catecholamines and GI homrones (CCK, gastrin) PROMOTE glucagon release
• Para and Symp stimulation PROMOTE glucagon release

Question 14

describe the effects of glucagon and insulin on ketogenesis

Answer 14

• glucagon promotes ketogenesis
• insulin inhibits ketogenesis
• Triglycerides to ketones or glucose

Question 15

describe the effects of glucagon and insulin on gluconeogenesis

Answer 15

• Insulin Inhibits
• glucagon promotes
• Amino acids (glycerol/lactate) to glucose

Question 16

describe the effects of glucagon and insulin on Glycogenesis

Answer 16

• Insulin promotes glycogenesis

- Glucose to glycogen (storage)

Question 17

describe the effects of glucagon and insulin on Glycogenolysis

Answer 17

• Glucagon promotes Glycogenolysis

- Glycogen to glucose (energy)

Question 18

describe the effects of glucagon and insulin on Glycolysis

Answer 18

• Insluin promotes glycolysis
• Glucagon inhibits
• Glucose to pyruvate

Question 19

what are the physiological impact of insulin, glucose and glucagon administration on blood glucose levels

Answer 19

• insulin decreases glucose in blood

- glucagon rapidly increases glucose in the blood

Question 20

Define IAPP

Answer 20

• produced by B cells
• packaged in same vesicles as insulin
• Decreases glucagon secretion
• inhibits GI motility
• regulates appetite

Question 21

Define pancreatic polypeptides

Answer 21

• secreted by F or PP cells in pancreas
• regulated by vagus nerve and neuronal control
• regulates exocrine function of pancreas, gallbladder contraction, gastric acid secretion and GI motility

Question 22

define Somatostatin

Answer 22

• secreted by Delta cells
• secreted in response to same stimuli as insulin
• produced also in brain, peripheral neurons, endocrine cells of stomach/pancreas
• INHIBITS insulin secretion thru activation of SSTR-5

Question 23

Define Ghrelin

Answer 23

• secreted by epsilon cells
• produced also in heart, lung, kidney, IS, hypothalamus and pituitary
• shown to INDUCE GASTRIC EMPTYING, gastric acid secretion and increase appetite

Question 24

define Glucagon related peptides (GLP)

Answer 24

• Can yield GLP1 or GLP2
• GLP1 secreted in response to meal (insulin AMPLIFIER) and promotes production and secretion of insulin and somatostatin (neg reg of insulin)
• GLP1 protects and promotes growth of B cells
• DPP-4 breaks down GLP1