McCumbee - Endocrine Pancreas

Question 1

Endocrine cells account for less than 2% of the total pancreatic mass, are organized in discrete clusters called _________

Answer 1

Islets of langerhans

Question 2

Beta cells in the islet of langerhans secrete __

Answer 2

Insulin

Question 3

Alpha cells in the islet of langerhans secrete

Answer 3

Glucagon

Question 4

Insulin is packaged into secretory granules as _______

Answer 4

Proinsulin

Question 5

The secretory granules that carry proinsulin also contain prohormone-converting enzymes that cleave proinsulin into? ___- and ___

Answer 5

Insulin

C peptide

Question 6

What is the half life of insulin (circulatory half life)

Answer 6

5-8 minutes

Question 7

The ______ is the principal site of insulin degradation

Answer 7

Liver

Question 8

Hormones released by the intestines during a meal that stimulate glucose-dependent insulin secretion

Answer 8

Incretins

Question 9

What are the causes of insulin release during a meal? (X3)

Answer 9

Glucose

Amino acids (basic AA’s have most response)

Incretins

Question 10

The principal incretins in humans are:

Answer 10

GLP-1

GIP

Question 11

Thru what transport method is insulin eventually released from beta cells?

Answer 11

Exocytosis

Question 12

Somatostatin _____ the Beta cell release of insulin

Answer 12

Inhibits

Question 13

Exercise and stress inhibit insulin release. This effect Is mediated by sympathetic stim via _______ adrenergic receptors

Answer 13

Alpha2

Question 14

This protein is part of the insulin signaling pathway and has many phosphorylatable tyrosines that are then able to be bound by various proteins with the SH2 domain, giving insulin a variety of functional capabilities

Answer 14

Insulin receptor substrate (IRS)

Question 15

___________ terminate insulin signal transduction by dephosphorylating the insulin receptor, IRS proteins, and other proteins phosphorylated during signal transduction

Answer 15

Protein-tyrosine phosphatases

Question 16

Signal intensity of insulin can be _______ by the phosphorylation of serine residues on the insulin receptors

Answer 16

Lessened

Question 17

_____ is the most physiologically important stimulus for the release of glucagon

Answer 17

Hypoglycemia

Question 18

The primary target of glucagon action is the _____

Answer 18

Liver

Question 19

The period time during which the cell metabolism consists primarily of the nutrients of that meal

Answer 19

Absorptive state

Lasts about 4 hours

Question 20

Explain the GLUT2 transporters role in glucose levels.

Answer 20

GLUT2 is a low-affinity glucose transporter that moves glucose into and out of hepatic cells by facilitated diffusion. Post meal, when glucose levels are high, it transports glucose into the hepatocytes for storage. When glucose levels in blood are low, it does not move glucose into the cell because of its low affinity When blood glucose levels are lower, and the hepatocytes are making glucose, the GLUT2 transporters take glucose out of the cell and move it to the bloodstream.

Question 21

Insulin ______ glucokinase expression

Answer 21

Increases

Question 22

Glucose entering the liver during the absorptive state does what?

Answer 22

It is converted to glucose-6-phosphate by glucokinase

Question 23

By regulating key enzymes in the liver, insulin ____ (x6)

Answer 23

Promotes the storage of glucose as glycogen.

Promotes glycolysis

Inhibits glycogenolysis

Prevents release of glucose by keeping in G-6-P form.

Inhibits gluconeogenesis

Stimulates fatty acid synthesis during period of carb excess

Question 24

Liver glycogen peaks ______ to ___ hours after a meal

Answer 24

4 to 6

Question 25

What sort of enzymatic response will you get if you eat a meal that is high in protein content and low in carbohydrate content?

Answer 25

Pancreas releases glucagon and insulin Insulin - because of AA’s in proteins Glucagon - low glucose medium, prevents insulin induced hypo-glycemia by stimulating hepatic glycogenolysis and gluconeogenesis

Question 26

Glucose uptake by skeletal muscle during absorptive state is regulated by?

Answer 26

Primarily insulin Lesser extent by blood glucose concentration

Question 27

What does insulin do to increase the glucose uptake by skeletal muscle in the absorptive state?

Answer 27

It stimulates the translocation of the GLUT4 transporter that are stored in the intracellular vesicles, increasing Vmax of transport.

Question 28

Insulin has a profound _________ effect on basal and hormonal stimulated lypolysis in fat cells

Answer 28

Inhibitory Insulin acts by inhibiting hormone sensitive lipase inside adipocytes

Question 29

What does insulin do to increase transport of glucose to adipocytes?

Answer 29

Signals the translocation of the GLUT4 transporters

Question 30

Insulin has a stimulatory effect on fatty acid synthesis by stimulating?

Answer 30

Synthesis of lipoprotein lipase which breaks TAG’s to FA’s and glycerol (Has to be done to get them in cell. Once in, combined w/ glycerol 3 phosphate to form IC TAG’s)

Question 31

Insulin has a profound inhibitory effect on basal and hormone stimulated lipolysis IN fat cells. Insulin acts by _______ hormone-sensitive lipase inside adipocytes.

Answer 31

Inhibiting (Hormone sensitive lipase catalyzes breakdown of TAG’s in fat cells into FA’s and glycerol) [epinephrine is most potent physiological stimulator of hormone-sensitive lipase activity]

Question 32

In the liver, insulin _____ ketogenesis

Answer 32

Suppresses

Question 33

Rate of ketogenesis increases as the rate of ______ increases

Answer 33

Rate of flux of FA into liver increases

Question 34

Insulin suppresses hepatic ketogenesis by ? (X2)

Answer 34

1. Blocking lipolysis (insulin is a very strong inhibitor of hormone-sensitive lipase) 2. Inhibiting carinitine acyltransferase (transfers fatty acids to mitochondria)

Question 35

The principal substrates for hepatic gluconeogenesis during a fast are: (x4)

Answer 35

AA’s and lactate (from skeletal muscle) Lactate (from RBC’s) Glycerol (from fat)

Question 36

Cortisol ______ protein catabolism

Answer 36

Promotoes | Important aspect of gluconeogenesis

Question 37

Insulin ______ protein catabolism

Answer 37

Inhibits

Question 38

Growth hormone levels increase w/in first 24 hours of a fast. What are the two effects on metabolism GH has that helps w/ fast

Answer 38

Stimulation of lipolysis Inhibition of glucose uptake by skeletal muscle and adipose tissue (send it to more important muscles)

Question 39

Plasma glucose, FFA, and glycerol levels usually stimulate after about ___ days of a fast

Answer 39

3

Question 40

____ hormone from the thyroid regulates basal metabolic rate and is dropped after a fast that lasts from days to weeks?

Answer 40

T3 | There is a 15-20% drop in basal metabolic rate in this kind of fast and T3 levels drop by half

Question 41

Glucose from blood enters brain thru?

Answer 41

Glucose transporters in the endothelial cells by facilitated diffusion

Question 42

Ketones enter the brain via?

Answer 42

Monocarboxylate transporters (MTC)

Question 43

Causes of hypoglycemia: (x6)

Answer 43

1. Drugs that potentiate effects of insulin or interfere w/ gluconeogenesis 2. Insulinomas 3. Rapid gastric emptying in pt’s w/ grastrectomies 4. Adrenal/pituitary insufficiency 5. Liver dz 6. Inborn errors of carbohydrate metabolism

Question 44

Hormones releases in response to hypoglycemia

Answer 44

Counterregulatory hormones

Question 45

What are some counterregulatory hormones (x4)

Answer 45

Glucagon Epinephrine GH Cortisol