Insulin and Glucagon

Question 1

What energy source lasts the longest: glucose, glycogen, protein, fat?

Answer 1

fat ! lasts 40 days

Question 2

What interval is plasma glucose mantained at?

Answer 2

80-100 mg/dL

Question 3

What do these cells of the islet of langerhan secrete:

1. beta cells
2. alpha cells
3. delta cells
4. F cells

Answer 3

1. insulin
2. glucagon
3. somatostatin
4. pancreatic polypeptide

Question 4

What is the half life of glucagon?

Answer 4

3-4 minutes

Question 5

Describe the processing of glucagon?

Answer 5

-secreted as 160 AA
-posttranslational processing:
glucagon -29
glicentin or enteroglucagon - 69
GLP, GLP1, GLP2

packaged and stored in membrane bound granules

Question 6

What are four stimulators of glucagon secretion?

Answer 6

1. hypoglycemia
2. inc in arginine and alanine
3. exercise
4. stress

Question 7

What are three inhibitors of glucagon secretion?

Answer 7

1. somatostatin
2. insulin
3. hyperglycemia

Question 8

What else is glucagon released in conjunction with, in response to stress?

Answer 8

catecholamines, growth hormone, cortisol

Question 9

What is the primary target of glucagon?

Answer 9

liver

Question 10

What three processes does glucagon induce?

Answer 10

1. glycogenolysis
2. gluconeogenesis
3. lipolysis

Question 11

What is proinsulin secreted with?

Answer 11

endopeptidase

and zinc

Question 12

What is proinsulin cleaved into?

Answer 12

insulin and C-peptide

Question 13

What does the level of C-peptide correlate to?

Answer 13

endogenous insulin production

in patients receiving exogenous insulin

Question 14

What is the half life of insulin?

Answer 14

5-8 minutes

Question 15

What is the pattern of insulin release after a meal? after an IV dose?

Answer 15

after a meal: fast release w/in 10 min and peaks about 30 min later

IV: first peak - stored insulin, falls in 10 min
if stim maintained - gradually inc during next hour

Question 16

After glucose influxes through the cell through GLUT2 transporter, what are the next steps leading to insulin release?

Answer 16

1. glucose metabolism - inc ATP
2. ATP inhibits K+ channel
3. Vm more positive –> depolarization
4. activation of volt gated ca2+ channel
5. ca2+ induced ca2+ release
6. exocytosis of insulin granules

Question 17

What other sugars besides glucose, and what AAs can also stimulate insulin release?

Answer 17

galactose and mannose

arginine and lysine (he also mentions leucine)

Question 18

Is the effect of insulin inhibiting glucagon mutual?

Answer 18

NO glucagon stimulates insulin secretion

to prevent degradation in muscle

Question 19

Why does oral glucose yield more insulin than IV glucose?

Answer 19

incretins provide advance notice of feeding and stimulate insulin secretion

CCK, GIP, GLP-1

Question 20

Does the PNS or SNS stimulate insulin secretion?

Answer 20

PNS

Question 21

What other hormones besides GIP, glucagon, and CCK enhance insulin secretion?

Answer 21

gastrin, secretin, VIP, epinephrine - B receptor

Question 22

What two hormones inhibit insulin secretion?

Answer 22

somatostatin and epinephrine - alpha receptor

Question 23

Which receptors of epinephrine are activated during exercise?

Answer 23

alpha and beta, but alpha predominates

Question 24

What is the net effect on insulin due to exercise?

Answer 24

it is suppressed - prevent hypoglycemia

Question 25

Does insulin or glucagon stimulate the synthesis of lipoprotein lipase to release fatty acids from chylomicrons and VLDL?

Answer 25

insulin | -increases the esterification of fats

Question 26

What happens during a glucose tolerance test for a patient with type 1 Diabetes?

Answer 26

plasma glucose rises to a higher level and remains there longer

Question 27

What can insulinemia result from?

Answer 27

insulin shots, insulinoma

Question 28

What can happen as a result of glucagonomas?

Answer 28

hyperglycemia

Question 29

What are orixigenic factors?

Answer 29

NTs that stimulate feeding | -neuropeptide Y

Question 30

What are anorexigenic factors

Answer 30

NTs that inhibit feeding | CRH, GLP-1, alpha MSH, CART

Question 31

What are satiety signals?

Answer 31

secreted in response to food ingestion -CCK, GLP1, Glicentin, GLP2, NPY, ghrelin

Question 32

What message is CCK sending when it binds to CCK1 receptors on the vagus?

Answer 32

fat and protein is being processed and will soon be absorbed

Question 33

Where does the vagus send signals to?

Answer 33

NTS and then to the hypothalamus

Question 34

What is grhelin and what is it secreted by?

Answer 34

only hormone that stimulates food intake | -secreted by oxyntic glands in the stomach

Question 35

What is the target of ghrelin? what are the effects?

Answer 35

ARC 1. inhibition of POMC/CART pathway 2. enhance NPY. AgRP pathway

Question 36

What are adiposity signals?

Answer 36

leptin and insulin | hormones secreted in proportion to amount of fat in the body

Question 37

What is leptin derived from?

Answer 37

white adipocytes

Question 38

Are leptin and insulin able to cross the BBB?

Answer 38

yes

Question 39

What pathways does leptin and insulin inhibit/enhance?

Answer 39

1. inhibits: AgRP/NPY 2. enhances POMC-->alphaMSH -decreases meal size

Question 40

What is the function of AgRP/NPY pathway?

Answer 40

stimulates food intake

Question 41

What is the function of the POMC pathway ?

Answer 41

inhibits the urge for food intake

Question 42

What does a leptin receptor mutation cause in humans and mice?

Answer 42

obesity

Question 43

What does a mutation in MC4R, the receptor for Alpha-MSH released from POMC cause??

Answer 43

obesity

Question 44

After weight loss what is the effect on: 1. leptin 2. insulin 3. cck 4. peptide YY 5. Grhelin 6. hunger

Answer 44

1. leptin - reduced before diet, remains low 2,3,4. insulin, CCK, Peptide YY -reduced at completion of diet, remains low 5. grhelin - inc at completion of diet, remains high 6. hunger - present and remains

Question 45

What does the study of the effect of hormones and diet determine?

Answer 45

long-term strategies to counteract hormonal response to diet programs may be needed to prevent obesity relapse