Metabolic States Chart

Question 1

In the fed state, what does the liver do?

Answer 1

Liver is the primary organ responsible for maintaining glucose homeostasis. After eating a carbohydrate meal, biosynthetic pathways that produce glucose (glycogenolysis, gluconeogenesis) are inhibited and metabolic pathways that store glucose (fatty acid biosynthesis, cholesterol biosynthesis, protein synthesis, glycogenogenesis) are activated. After eating a protein rich meal, elevated amino acids in the blood increase the secretion of glucagon by pancreatic alpha cells. In this case, excess amino acids are used by the liver for gluconeogenesis.

Question 2

In the fed state, what does skeletal muscle do?

Answer 2

Glycolysis, fatty acid beta oxidation, glycogenogenesis, protein synthesis

Question 3

In the fed state, what does cardiac muscle do?

Answer 3

Fatty acid beta oxidation (60-80 percent); oxidation of glucose to lactate (20-40 percent).

Question 4

In the fed state, what does the brain do?

Answer 4

Oxidizes glucose to CO2 to make ATP through oxidative phosphorylation.

Question 5

In the fed state, what do intestinal epithelial cells do?

Answer 5

Convert glutamine and aspartate from the diet to alpha-ketoglutarate. In the fed state, gut epithelial cells use glutamine, aspartate and glutamate as their primary fuel. These amino acids come from the lumen of the gut, from dietary protein.

Question 6

In the fed state, what do colonocytes do?

Answer 6

Use short chain fatty acid produced by gut bacteria

Question 7

In the fed state, what do adipose cells do?

Answer 7

Ferments glucose to glycerol-3-phosphate, the backbone for triacylgqcerol synthesis.

Question 8

In the fasted state, what does the liver do?

Answer 8

The liver increases production and export of glucose fro use by other tissues. Glycogenolysis uses hepatic glycogen stores. Gluconeogenesis uses carbon skeletons from amino acids, lactate, and glycerol to produce glucose. The ATP to power gluconeogenesis comes from the FAD(2H) and NADH reduced by fatty acid beta oxidation. The acetyl CoA produced by fatty acid beta oxidation is a substrate for ketone body synthesis.

Question 9

In the fasted state, what does the skeletal muscle do?

Answer 9

Proteolysis produces free amino acids. Branched chain amino acids are used by the muscle as fuel. Alanine and glutamine are exported for use as gluconeogenic substrates but the liver. As the fast prolongs, skeletal muscle can use ketone bodies (made up of fat) for energy.

Question 10

In the fasted state, what does cardiac muscle do?

Answer 10

Fatty acid beta oxidation increases; glycolysis decreases

Question 11

In the fasted state, what happens in gut epithelial cells?

Answer 11

Gut epithelial cells still use glutamine as their primary fuel in the fasted state, but it comes from the blood, not the lumen of the gut.

Question 12

In the fasted state, what happens in the adipose tissue?

Answer 12

Lipolysis of triacylglycerol produces fatty acids (used as fuel by heart, liver) and glycerol (used for gluconeogenesis by liver).

Question 13

In the starved state, what does the liver do?

Answer 13

Liver increases its production of ketone bodies. The liver decreases gluconeogenesis.

Question 14

In the starved state, what does skeletal muscle do?

Answer 14

Ketone body utilization by skeletal muscle decreases, skeletal muscle breakdown decreases

Question 15

In the starved state, what does cardiac muscle do?

Answer 15

Cardiac muscle continues to use fatty acids; the heart does not like to use ketone bodies

Question 16

In the starved state, what does the brain do?

Answer 16

Ketone body utilization by brain increases!

Question 17

In the hypercatabolic state, what does the liver do?

Answer 17

Liver needs insulin for protein synthesis during wound repair.

Question 18

In the hypercatabolic state, what does the skeletal muscle do?

Answer 18

Sustained muscle and organ protein breakdown

Question 19

In the hypercatabolic state, what does the cardiac muscle do?

Answer 19

Sustained muscle and organ protein breakdown

Question 20

What does EPI do in hypercatabolism?

Answer 20

Activates hormone sensitive liapse – leads to fatty acids mobilized from adipose

Question 21

What does Cortisol do in hypercatabolism?

Answer 21

Activates muscle proteolysis – leads to amino acids mobilized from muscle

Question 22

What does Glucagon do in hypercatabolism?

Answer 22

Activates hepatic glycogenolysis and gluconeogenesis