Metabolism review (1.2)

Question 1

What is the most important hormone in the fed state?

Answer 1

Insulin…in DIRECT response to GLUCOSE

What would this mean after a high protein/low carb meal?…less insulin and more glucagon

Question 2

What does insulin activate?

Answer 2

Phosphatases…removes phosphate groups

Question 3

What is the downstream effect of insulin on Glycogen Synthase Kinase 3 (GSK3)?

Answer 3

Dephosphorylation –> activation –> synthesizing glycogen

Makes sense to create energy storage in the fed state

Question 4

What is the downstream effect of insulin on Protein Phosphatase 1 (PP1)?

Answer 4

Dephosphorylation –> inactivation –> does NOT break down glycogen storage

Makes sense to not deplete energy storage in the fed state

Question 5

What signaling pathway does insulin activate that leads to increased transcription?

Answer 5

MAPK cascade…in this case it’s activating kinases

Question 6

What happens in the liver during the fed state?

Answer 6

Glucose producing pathways are inhibited

Glucose storing pathways are activated

Question 7

What happens in the brain during the fed state?

Answer 7

Oxidizes glucose via ETC

Question 8

What happens in the RBCs during the fed state?

Answer 8

Fermentation of pyruvate –> lactate

No mitochondria = No ETC

Makes sense to not have RBCs use up the O2 they are supposed to be bringing around for other cells to use

Question 9

What happens in white adipose cells during the fed state?

Answer 9

Ferments glucose to glycerol 3-phosphate

Uses as a backbone for triacylglycerol synthesis

Question 10

What happens in skeletal muscle during the fed state?

Answer 10

Glycolysis
Fatty acid beta-oxidation
Glycogenogenesis
Protein synthesis

Question 11

What happens in cardiac muscle during the fed state?

Answer 11

Fatty acid beta-oxidation (60-80%)

Oxidation of glucose –> lactate (20-40%)

Question 12

What happens in intestinal epithelial cells during the fed state?

Answer 12

Conversion of glutamate, glutamine, and aspartate (from the diet) –> alpha-ketoglutarate (for TCA cycle)

Question 13

What happens in colonocytes during the fed state?

Answer 13

Use short chain fatty acids produced by gut bacteria

Question 14

What is the primary hormone during the fasted state?

Answer 14

Glucagon (from pancreas alpha cells)

Question 15

What kind of receptor does glucagon bind to? what is the downstream effect?

Answer 15

GPCR

Think phosphorylation

Question 16

What happens in the liver during the fasted state?

Answer 16

Glycogenolysis

Gluconeogenesis

Question 17

Where does the energy required for gluconeogenesis come from?

Answer 17

Fatty acid beta-oxidation

FADH2/NADH –> ATP

Question 18

Besides FADH2 and NADH, what else is made during FA beta-oxidation? How is it used?

Answer 18

Acetyl CoA

Ketone body synthesis (in the liver)…brain energy

Question 19

What happens in skeletal muscle during the fasted state?

Answer 19

Proteolysis

If a persistent fast…may use ketone bodies for energy

Question 20

Which amino acids are used for fuel by muscles in the fasted state?

Answer 20

Branched chain amino acids (leucine, isoleucine, valine)

Question 21

Which amino acids are used fro gluconeogenesis?

Answer 21

Alanine (–> pyruvate)

Glutamine (–> alpha-ketoglutarate)

Question 22

What happens in cardiac muscle during the fasted state?

Answer 22

FA beta-oxidation increases

Glycolysis decreases…but isn’t shut off

Question 23

What happens in the gut during the fasted state?

Answer 23

Glutamine from BLOOD for energy

Question 24

What happens in white adipose tissue during the fasted state? What are the products used for?

Answer 24

Lipolysis

FAs (fuel for heart and liver)
Glycerol (gluconeogenesis in the liver)

Question 25

What is the primary source of fuel in the starved state?

Answer 25

Fatty acids (increased lipolysis)

Proteolysis and gluconeogenesis are DECREASED

Question 26

What does cardiac muscle use as an energy source during the starved state?

Answer 26

Fatty acids (heart uses FAs…remember that)

Does not like using ketone bodies

Question 27

What is the effect of epinephrine during hypercatabolism?

Answer 27

Activates hormone sensitive lipase

Smaller player

Question 28

What is the effect of cortisol during hypercatabolism?

Answer 28

Activates muscle proteolysis

Bigger player

Question 29

What is the effect of glucagon during hypercatabolism?

Answer 29

Activates glycogenolysis and gluconeogenesis