Endocrine cells of the pancreas

Question 1

What do b cells secrete?

Answer 1

insulin and C peptide

Question 2

What do alpha cells secrete?

Answer 2

Glucagon

Question 3

What do delta cell secrete?

Answer 3

Somatostatin

Question 4

What do F cells (PP cells) secrete?

Answer 4

Pancreatic polypeptide

Acts as a satiety signal

Question 5

How does blood flow in the islets?

Answer 5

From center to periphery

Question 6

How is insulin formed?

Answer 6

Preproinsulin –> proinsulin –> insulin and C peptide

Proinsulin still has C peptide attached

Proinsulin is packaged into secretory granules and then cleaved

Question 7

What are the steps of insulin release?

Answer 7

Glucose enters cell via GLUT-2

Glucose is phyosphrylated by glucokinase

Glucose-6-phosphate is oxidized promoting ATP generation

ATP closes the “inward rectifying” K+ channels

Plasma membrane is depolarized and Ca2+ channels activate

Ca2+ enters cell and causes insulin and C-peptide to exocytosis

Question 8

What closes the K+ channels?

Answer 8

ATP

Question 9

What is the sulfonylurea receptor?

Answer 9

Increases insulin secretion by causing easier depolarization and more ca2+ entry

Question 10

What are the intracellular steps of glucose uptake through GLUT4?

Answer 10

Insulin binds to receptor

physophorylation of insulin receptor substrate

Substrate proteins phosphorylate and activate/inactivate downstream pathways

Translocation of vesicles containing GLUT4 to membrane

Glucose enters via facilitated diffusion

Question 11

What do MAP kinase, PI3k, and AKT do?

Answer 11

Increase glycogen/lipid/protein synthesis

decrease lipolysis

cell growth and differentiation

Question 12

What does activation of AMP-kinase result in?

Answer 12

GLUT4 translocation to plasma membrane

this is indepedent of insulin

Question 13

What are stimulatory factors of insulin secretion?

Answer 13

Increased glucose, AA, FA, and ketoacid concentration

Glucagon

Cortisol

GIP

K+

Vagal Stimulation, Ach

Sulfonylurea drugs

Question 14

What are inhibitory factors of insulin secretion?

Answer 14

Decreased blood glucose

Fasting

Exercise

Somatostatin

alpha-adrenergic agonists; norepinephrine

Diazoxide (K+ channel activator, relaxes smooth muscle)-used to treat hypoglycemia

Question 15

How does insulin affect skeletal muscle?

Answer 15

Increased glucose uptake

Increased glycogen synthesis

Incrased glycolysis and CHO oxidation

Increased protein synthesis

Decreased protein breakdown

Question 16

How does insulin affect the liver?

Answer 16

Increases glycolysis and CHO oxidation

Decrease gluconeogensis

Increase pyruvate oxidation

Increase lipid storage and decrease lipid oxidation

Question 17

How does insulin affect adipose tissue?

Answer 17

Increased glucose uptake

Increased glycolysis

Decreased lipolysis

Promotes uptake of fatty acids

Question 18

How does insulin affect blood levels of certain substances?

Answer 18

The effect on blood level is the opposite of the action of insulin

Ex. Insulin increases protein synthesis so there are decreased AA in the blood

Question 19

Where is glucagon stored?

Answer 19

In dense granules of Alpha-cells

Question 20

What stimulates the secretion of glucagon?

Answer 20

Decreased blood glucose

Increased AA (arginine & alanine)

Fasting

CCK

B-adrenergic agonists

Ach

Question 21

What inhibits glucagon production and secretion?

Answer 21

Insulin

Somatostatin

FA

Ketoacids

Question 22

What are the affects of glucagon secretion?

Answer 22

Increased blood glucose

Increased glucoenogensis

Increased glucogenolysis

Inhibits glycogen synthesis

Question 23

Explain general diabetes for the blood

Answer 23

Insulin resistance –> decreased tissue glucose utilization –> spills over into blood –> hyperglycemia

Question 24

Explain general diabetes for adipose tissue

Answer 24

Increased lipolysis (free fatty acids) –> Polyphagia

Increased lipolysis–> gluconeogenesis and ketogenesis

Question 25

Explain diabetes for muscle

Answer 25

Increased protein catabolism (amino acids) --\> gluconeogenesis

Question 26

Explain general diabetes for liver

Answer 26

Glucagon excess leads to increased gluconeogenesis and Ketogenesis

Question 27

Explain general diabetes for the kidney

Answer 27

Ketoacidosis and hyperglycemia lead to ketonuria and glycosuria --\> polyuria--\>volume depletion--\> polydipsia

Question 28

What is type 1DM?

Answer 28

Destruction of B-cells Decreased utilization of ketoacids results in diabetic ketoacidosis (DKA)

Question 29

What are some results of type 1 DM?

Answer 29

Hyperkalemia-shift of K+ out of cells Increased blood glucose increased filtered load of glucose, exceeds reabsorptive capacity of proximal tubule

Question 30

What are some drawbacks of Type 1 DM insulin replacement?

Answer 30

Lag between glucose measurement & insulin dosing delayed absoprtion of insulin following injections

Question 31

What is type 2 DM?

Answer 31

Exhaustion of active B-cells due to environmental factors patients produce insulin but often have to produce more and more

Question 32

What are the results of obesity induced insulin resistance?

Answer 32

Decreased GLUT-4 uptake of glucose in response to insulin Decreased ability of insulin to repress hepatic glucose production Inability of insulin to repress adipose tissue uptake (LPL) and lipolysis (HSL)

Question 33

How else can Type 2 diabetes occur in non-obese patients?

Answer 33

Due to decreased insulin release by pancreas indepedent of peripheral insulin resistance

Question 34

What are incretin hormones and what do they do?

Answer 34

Hormones in the intestinne that are secreted in response to GI glucose and fat Stimulates insulin secretion Inhibits glucagon secretion Slows gastric emptying

Question 35

What are some associated conditions of type 1 DM?

Answer 35

Autoimmune thyroid disease celiac disease addison's disease

Question 36

What are some associated conditions to type 2 DM?

Answer 36

Obesity lipid abnormalities