Ch 19 Fuel Metabolism

Question 1

What is the primary function of the liver after a meal?

Answer 1

The liver takes up glucose and converts it to glycogen for storage.

Question 2

What do muscle cells do with glucose when it is available?

Answer 2

Muscle cells take up glucose and store it as glycogen.

Question 3

What is acetyl-CoA used for in metabolic processes?

Answer 3

Acetyl-CoA is used to synthesize fatty acids.

Question 4

During a fast, what does the liver do with glycogen?

Answer 4

The liver mobilizes glucose from glycogen stores and releases it into the circulation.

Question 5

What happens to lactate and alanine produced by muscle activity during fasting?

Answer 5

The liver converts lactate and alanine to glucose and disposes of amino groups through urea synthesis.

Question 6

What are ketone bodies used for when glucose is in short supply?

Answer 6

Ketone bodies are used to power the brain and heart.

Question 7

What is the Cori cycle?

Answer 7

The Cori cycle transfers free energy from the liver to the muscles.

Question 8

What does the glucose-alanine cycle do?

Answer 8

The glucose-alanine cycle transports nitrogen from muscles to the liver.

Question 9

What role does insulin play in fuel metabolism?

Answer 9

Insulin stimulates glucose uptake and inhibits glycogen breakdown.

Question 10

What triggers the release of insulin?

Answer 10

An increase in blood glucose concentrations triggers the release of insulin.

Question 11

What are the metabolic effects of insulin on muscle?

Answer 11

Promotes glucose transport, stimulates glycogen synthesis, suppresses glycogen breakdown.

Question 12

How does insulin affect adipose tissue?

Answer 12

Activates lipoprotein lipase, increases acetyl-CoA carboxylase, stimulates triacylglycerol synthesis, suppresses lipolysis.

Question 13

What does insulin do in the liver?

Answer 13

Promotes glycogen synthesis, promotes triacylglycerol synthesis, suppresses gluconeogenesis.

Question 14

Where is insulin synthesized?

Answer 14

Insulin is synthesized in the β cells of pancreatic islets.

Question 15

What is the role of glucagon in fuel metabolism?

Answer 15

Glucagon mobilizes glucose when blood glucose concentration drops below about 5 mM.

Question 16

What effect does epinephrine have on fuel metabolism?

Answer 16

Epinephrine triggers fuel mobilization.

Question 17

What does AMP-dependent protein kinase (AMPK) regulate?

Answer 17

AMPK regulates metabolic processes in response to energy levels.

Question 18

What metabolic change occurs during starvation?

Answer 18

The body shifts from using carbohydrates to using fatty acids and amino acids for energy.

Question 19

What percentage of energy comes from carbohydrates immediately after a meal?

Answer 19

50% of energy comes from carbohydrates.

Question 20

What is the primary energy source after a 40-day fast?

Answer 20

95% of energy comes from fatty acids.

Question 21

What is the main characteristic of brown adipose tissue?

Answer 21

Brown adipose tissue is full of mitochondria for generating heat.

Question 22

What are the symptoms of diabetes mellitus?

Answer 22

High blood glucose, excessive urination, and potential organ damage.

Question 23

What distinguishes type 1 diabetes from type 2 diabetes?

Answer 23

Type 1 is insulin-dependent and an autoimmune disease, while type 2 is often due to insulin resistance.

Question 24

What is the Warburg effect in cancer metabolism?

Answer 24

Cancer cells generate precursors for nucleotide, amino acid, and fatty acid synthesis through increased glycolysis.

Question 25

Fill in the blank: Insulin is released from pancreatic ___ cells in response to ____ blood glucose.

Answer 25

β; high

Question 26

Which enzyme is the better sensor of glucose concentration?

Answer 26

Glucokinase

Question 27

What happens to GLUT4 in muscle cells upon insulin binding?

Answer 27

GLUT4 translocates to the cell surface, increasing glucose transport.

Question 28

Which organ has the capacity to generate glucose through gluconeogenesis?

Answer 28

Liver

Question 29

Which cycle functions to transfer nitrogens to the liver?

Answer 29

The glucose-alanine cycle.

Question 30

Which cycle transfers nitrogens to the liver?

Answer 30

The Cori cycle ## Footnote The Cori cycle is involved in the conversion of lactate to glucose in the liver.

Question 31

What is the purpose of the glucose-alanine cycle?

Answer 31

Returns alanine from the liver to the muscle ## Footnote The glucose-alanine cycle is important for nitrogen transport and gluconeogenesis.

Question 32

Which cycle synthesizes glucose in the liver to replenish glucose in muscle?

Answer 32

The Cori cycle ## Footnote This process helps maintain energy levels during anaerobic metabolism.

Question 33

Glycogen phosphorylase is allosterically ______ by ATP.

Answer 33

inhibited ## Footnote High levels of ATP signal that energy is sufficient, thus inhibiting glycogen breakdown.

Question 34

The hormone ______ stimulates the liver to generate glucose by glycogenolysis and gluconeogenesis.

Answer 34

glucagon ## Footnote Glucagon is released when blood glucose levels are low to increase glucose availability.

Question 35

The hormone ______ stimulates lipolysis in adipocytes.

Answer 35

epinephrine ## Footnote Epinephrine plays a key role in mobilizing energy stores during stress or exercise.

Question 36

The hormone ______ stimulates muscle to generate glucose by glycogenolysis.

Answer 36

epinephrine ## Footnote This hormone helps provide energy during physical activity by promoting glycogen breakdown.