Metabolic Effects of Glucagon and Insulin

Question 1

What four organs play a dominant role in fuel metabolism?

Answer 1

• liver
• adipose tissue
• muscle
• brain
  (don’t work in isolation but in network with each other)

Question 2

Each of the four main organs is specialized for what three things?

Answer 2

• storage
• use
• generation of specific fuels

Question 3

What two hormones control the integration of energy metabolism?

Answer 3

insulin and glucagon

Question 4

What two hormones play a supporting role in integration of energy metabolism?

Answer 4

epinephrine and norepineprine

Question 5

What polypeptide hormone is produced and secreted by the beta cells of the islets of Langerhans?

Answer 5

• insulin

Question 6

Insulin’s metabolic effects are ____.

Answer 6

anabolic

Question 7

True or False? Insulin and glucagon release is always coordinated?

Answer 7

True

Question 8

Insulin synthesis and secretion are stimulated by what three things?

Answer 8

• glucose
• amino acids (especially arginine)
• gastrointestinal hormones (secretin)

Question 9

What is the most important stimulus for insulin secretion?

Answer 9

glucose

Question 10

What inhibits insulin secretion?

Answer 10

• scarce dietary fuels
• stress (fever or infection)
• epinephrine (trauma or extreme exercise)

Question 11

What three tissues are the effects of insulin most prominent?

Answer 11

• liver
• muscles
• adipose

Question 12

How does insulin effect the liver?

Answer 12

inhibits gluconeogenesis and increases glycogen synthesis

Question 13

How does insulin effect the muscles?

Answer 13

increased glycogen synthesis, glucose uptake by increasing the number of transporters

Question 14

How does insulin effect adipose tissue?

Answer 14

increased glucose uptake

Question 15

What does insulin do?

Answer 15

decreases blood glucose

Question 16

_____ causes a significant reduction in the release of fatty acids.

Answer 16

Insulin

Question 17

Insulin _____ triacylglycerol degradation and ______ triacylglycerol synthesis.

Answer 17

decreases, increases

Question 18

True or False? Insulin causes the uptake of glucose to be stored as glycogen in the liver and muscles or as triacylglycerol in adipose tissue.

Answer 18

True

Question 19

Insulin binds to high affinity receptors that have alpha and beta subunits. What do the alpha and bet subunits do?

Answer 19

beta subunit: hydrophobic and contains tyrosine kinase that is activated by insulin
alpha subunit: insulin binding site

Question 20

How does insulin effect membranes?

Answer 20

GLUT-4 transporters are recruited

Question 21

True or False? Some tissue do not require insulin for glucose transport?

Answer 21

True

Question 22

How does the insulin receptor regulate insulin?

Answer 22

It downregulates it by endocytosing the receptor containing the bound insulin

Question 23

How long does it take for GLUT-4 transporters to increase in skeletal muscle and adipose tissue?

Answer 23

seconds

Question 24

What polypeptide is secreted by alpha cells of the pancreatic islets of Langerhans?

Answer 24

glucagon

Question 25

Glucagon (along with epinephrine, cortisol, and growth hormone) is considered a "_______ hormone."

Answer 25

counterregulatory

Question 26

What is the main job of glucagon?

Answer 26

it prevents hypoglycemia by initiating certain metabolic pathways

Question 27

What are the three stimuli for glucagon secretion?

Answer 27

- low blood glucose - amino acids (glucagon secreted with insulin to prevent hypoglycemia) - epinephrine (during stress or exercise, glucagon is secreted in anticipation of increased glucose use)

Question 28

What inhibits glucagon?

Answer 28

- increased blood glucose | - insulin

Question 29

Glucagon increases blood glucose concentration by _____ and _____.

Answer 29

initiating glycogenolysis and gluconeogenesis in the liver

Question 30

_____ causes hepatic oxidation of fatty acids.

Answer 30

Glucagon

Question 31

_____ causes increased amino acid uptake by the liver.

Answer 31

glucagon

Question 32

What is characterized by confusion, aberrant behavior and possible coma?

Answer 32

hypoglycemia

Question 33

True or False? | Hypoglycemia symptoms can be resolved within minutes of glucose ingestion.

Answer 33

True

Question 34

Why is hypoglycemia considered a medical emergency?

Answer 34

The CNS demands a constant supply of blood-borne glucose.

Question 35

What two hormones are the two most important in preventing hypoglycemia?

Answer 35

glucagon and epinephrine

Question 36

What disease includes symptoms of adrenergic and neuroglycopenia?

Answer 36

hypoglycemia

Question 37

Receptors in what area mediate release epinephrine, ACTH, and growth hormone?

Answer 37

hypothalamus

Question 38

What are the three types of hypoglycemia?

Answer 38

- insulin-induced - postprandial - fasting

Question 39

What is insulin-induced hypoglycemia caused by?

Answer 39

diabetics who administer too much insulin

Question 40

What causes posprandial hypoglycemia?

Answer 40

exaggerated insulin release following a meal

Question 41

What is fasting hypoglycemia caused by?

Answer 41

when the liver is unable to produce adequate glucose levels during periods of fasting or by a Beta cell tumor

Question 42

True or False? Hypoglycemia can result from alcohol intoxication.

Answer 42

True

Question 43

Alcohol consumption can cause dangerous hypoglycemia in individuals who:

Answer 43

- have exercised strenuously for a prolonged time - are fasting - take insulin for diabetes