Metabolic Hormones

Question 1

hormones

Answer 1

signaling molecules released by endocrine cells/tissues to influence the function of distant or neighboring cells and organs

Question 2

islets of langerhan

Answer 2

endocrine component of the pancreas that contains A, B, D, and F cells

Question 3

a cells

Answer 3

produce glucagon

Question 4

b cells

Answer 4

produce insulin and amylin

Question 5

d cells

Answer 5

produce somatostatin

Question 6

glut 2

Answer 6

located on pancreatic B cells

transports glucose into the cell; senses levels of glucose in the blood to regulate insulin secretion

insulin INDEPENDENT

Question 7

glut 4

Answer 7

located in skeletal muscle and fat cells

transports glucose into skeletal muscle and fat cells; translocates to cell surface in response to insulin

insulin DEPENDENT

Question 8

insulin

Answer 8

dipeptide hormone produced by B cells in the islets of langerhan in the pancreas

Question 9

function of insulin

Answer 9

decrease blood glucose by:
- increasing glucose uptake by skeletal muscle and fat cells
- decreasing glucose production in the liver

Question 10

insulin synthesis

Answer 10

proinsulin –> A/B chains stabilized by disulfide bridges –> C chain cleaved off –> insulin

Question 11

what stimulates insulin secretion

Answer 11

hyperglycemia

Question 12

steps of insulin secretion

Answer 12

1. glucose enters pancreatic B cells via GLUT2 transporters
2. glucokinase converts glucose –> G6P
3. G6P –> ATP –> opens K+ channels –> depolarizes cell
4. depolarization opens Ca2+ channels –> Ca2+ influx
5. Ca2+ influx causes insulin containing vesicles to mobilize to cell surface and exocytose

Question 13

insulin receptor

Answer 13

tyrosine kinase receptor

2 extracellular a subunits
2 intracellular B subunits w/ tyrosine residues

Question 14

what cells have insulin receptors on them

Answer 14

muscle, adipose tissue, liver

Question 15

mechanism of insulin binding to target cells

Answer 15

1. insulin binds receptor
2. tyrosine resides on either subunit autophosphorylate each other
3. active tyrosine residues phosphorylate IRS-1
4. IRS-1 activates PI3 kinase
5. PI3K causes translocation of GLUT4 transporters to cell surface
6. glucose enters cell via GLUT4 transporters

Question 16

effects of insulin in the liver

Answer 16

1. stimulate glycogen synthesis
2. inhibit glycogenolysis
3. inhibit gluconeogenesis
4. stimulate FA synthesis
5. stimulate glycolysis

Question 17

effects of insulin in skeletal muscle

Answer 17

1. stimulate glucose uptake via GLUT4
2. increase glycogen storage
3. stimulate glycolysis

Question 18

effects of insulin in adipose tissue

Answer 18

1. stimulates lipoprotein lipase and fatty acid synthase (lipogenesis)
2. inhibits fat mobilization
3. stimulates glycolysis
4. stimulates leptin

Question 19

effects of insulin the the brain

Answer 19

1. inhibits feeding behavior
2. increases metabolic rate

Question 20

insulin resistance

Answer 20

reduced ability of insulin to perform its normal actions in target cells

Question 21

causes of insulin resistance

Answer 21

1. obesity
2. corticosteroids/Cushing’s
3. inflammation
4. oxidative stress
5. free fatty acid accumulation

Question 22

effects of insulin resistance

Answer 22

hyperinsulinemia –> diabetes

Question 23

glucagon

Answer 23

polypeptide hormone produced by A cells in pancreas

Question 24

function of glucagon

Answer 24

increase blood glucose by:
- stimualting glyocenolysis
- stimulating gluconeogenesis

Question 25

what is glucagon derived from

Answer 25

proglucagon

Question 26

what stimulates glucagon secretion

Answer 26

hypoglycemia and epinephrine

Question 27

function of epinephrine

Answer 27

increases hepatic glucose production –> increases blood glucose

• inhibits insulin
• stimulates glucagon

Question 28

function of glucocorticoids

Answer 28

increases hepatic glucose production and inhibits glucose uptake by tissues –> increases blood glucose

• chronic high levels of glucocorticoids causes Cushing’s –> can develop insulin resistance and diabetes