Metabolism Review - Skildum

Question 1

What accounts for the majority of the stored chemical energy in your body

Answer 1

triacylglycerol

most dense form of energy in the body

Question 2

24 hours after a meal, what is the major source of blood glucose?

Answer 2

Gluconeogenesis in the liver

Question 3

How does muscle change its use of fuel as the body fasts from 1 day to 1 week.

Answer 3

muscle adapts to use fatty acid in order to preserve ketone bodies for use in the brain

Question 4

Why can’t RBC’s use fatty acids for energy?

CHECK THIS ONE

Answer 4

RBC’s do not have mitochondria

Question 5

What is the difference in how much energy is packed into glucose, fatty acids, or amino acids?

Answer 5

Glucose: 4 kCal/g

Fatty Acids: 9 kCal/g

Amino Acids: 4 kCal/g

Question 6

Most important hormone regulating glucose storage pathways in the fed state?

What does it directly respond to?

Answer 6

Insulin

Directly responsive to concentration of glucose in the blood

(Insulin also inhibits glucagon release)

Question 7

Does the relative amount of carbs to protein affect the amount of insulin release in the fed state?

Answer 7

High carbs = more insulin

High protein = less insulin, more glucagon

Question 8

What is the general overview of the mechanism between insulin binding to its receptor and gene transcription to promote glucose uptake?

Answer 8

• Insulin binds tyrosine kinase receptor
• MAP-kinase pathway is activated
• Transcription in cells creates proteins that form glucose uptake channels

Question 9

What organ is primarily responsible for maintaining glucose homeostasis?

What happens after you eat a carb-rich meal?

Answer 9

Liver responsible

After carb-rich meal:

• Pathways producing glucose are shut down (Glycogenolysis, gluconeogenesis)
• Pathways storing glucose are activated (fatty acid biosynthesis, protein synthesis, glycogenogenesis)

Question 10

Organ responses to feeding:

Intestinal Epithelium:
Colonocytes:

Answer 10

Intestinal epithelial cells
Convert glutamine, glutamate and aspartate from the diet to a-ketoglutarate.

Colonocytes
Use short chain fatty acids produced by gut bacteria.

Question 11

Organ responses to feeding:

Brain:
RBC’s:
White adipose Cells:

Answer 11

Brain:
Oxidizes glucose to CO2 to make ATP

Red blood cells:
Ferments glucose to pyruvate; exports lactate.

White adipose cells:
Ferments glucose to glycerol 3-phosphate, for triacylglycerol synthesis.

Question 12

Organ responses to feeding:
Cardiac Muscle:
Skeletal Muscle:

Answer 12

Skeletal muscle
Glycolysis, fatty acid beta oxidation, glycogenogenesis, protein synthesis

Cardiac muscle
Fatty acid beta oxidation
Oxidation of glucose and lactate

Question 13

Describe the glucagon receptor and the mechanism by which it promotes glycogenolysis:

Answer 13

Glucagon receptor = 7 trans-membrane domain G-protein coupled receptor

Binding activates adenylyl cyclase, cAMP, and PKA

Inactivates glycogen synthase
Activates glycogen phosphorylase

Question 14

Where does the body get the ATP used to power gluconeogenesis?

Answer 14

FADH2 and NADH that is reduced by fatty acid oxidation

Question 15

What does skeletal muscle use as fuel in the fasting state?

Answer 15

Branch chain amino acids.

As fast prolongs, skeletal muscle can also use ketone bodies for energy

Question 16

What do gut epithelial cells use for fuel in the fasted state compared to the fed state?

Answer 16

Fed - use glutamine primarily, from gut lumen

Fasted - use glutamine primarily, from blood

Question 17

What does white adipose tissue to in the fasted state?

Answer 17

Lipolysis of triacylglycerols to produce fatty acids and glycerol
(fatty acids fuel for heart and liver) (glycerol used by liver for gluconeogenesis)

Question 18

During starvation state, what changes does your body make

Answer 18

• Lipolysis of Triacyclglycerols increases
• The liver makes more ketone bodies
• Skeletal muscle stops using ketone bodies so the brain can use them
• Cardiac muscle continues to use fatty acids because it doesn’t use ketones
• Skeletal muscle breakdown stops, the liver stops gluconeogenesis
• Glucose saved for RBCs

Question 19

What will happen to urea cycle activity after:

• overnight fast
• prolonged starvation

Answer 19

overnight - urea cycle activity increases

starved - urea cycle deceases, because you have switched to fatty acid metabolism

Question 20

What hormone is responsible for muscle breakdown?

Answer 20

Cortisol!

Question 21

What hormone is responsible for mobilizing fatty acids from adipose tissue?

Answer 21

Epinephrine

Question 22

Maintaining a positive nitrogen balance is an important nutritional goal for all recovering patients.

What is the general equation used to insure your patient is in positive balance?

Answer 22

Grams of protein per day x .16 will give you the amount of ingested nitrogen

Nitrogen balance =
Nitrogen intake - (urinary urea nitrogen + 2)

Change the 2 to a 3 in pediatrics, 4 if kids are receiving total parenteral nutrition

Question 23

What does gut epithelial cells and lymphocytes have in common that would make them both use gluatmine as a fuel source?

Answer 23

Both have VERY rapid turnover. By not using glucose for energy they can use glucose for other things like ribose synthesis

Question 24

Creatinine tests can be used to measure kindey function. What is another use for the test?

Answer 24

Can test for a person’s muscle mass.

Combined with height, creatitine height index is used to measure nutritional status

Question 25

Accounts for majority of chemical energy in the body:

Answer 25

Triacyglycerol

Question 26

24 hours after a meal, which one of the following is most likely to occur?

• Fatty acids released from adipose tissue provide carbon for synthesis of glucose.
• Gluconeogenesis in the liver will be the major source of blood glucose.
• Ketone bodies provide carbon for gluconeogenesis.
• Muscle converts amino acids to blood glucose.
• Muscle glycogenolysis provides glucose to the blood.

Answer 26

Gluconeogenesis in the liver will be the major source of blood glucose.

Question 27

In a well nourished individual, as the length of fasting increases from overnight to one week, which one of the following is most likely to occur?

• Adipose triacylglycerol stores are nearly depleted
• Blood glucose levels decrease by approximately 50%
• Brain begins to use fatty acids as a major fuel
• Muscle decreases its use of ketone bodies, which increase in the blood
• Red blood cells switch to using ketone bodies

Answer 27

Muscle decreases its use of ketone bodies, which increase in the blood

Why?

Because it let’s the brain use the ketones when starvation occurs

Question 28

A hospitalized patient had low levels of serum albumin and high levels of blood ammonia. His creatinine – height index (CHI) was 98% and his body mass index (BMI) was 20.5. Blood urea nitrogen (BUN) was not elevated. The diagnosis most consistent with these findings is. . .

• Anorexia nervosa
• Decreased absorption of amino acids by intestinal epithelial cells (e.g. celiac disease)
• Kwashiorkor (protein malnutrition)
• Loss of hepatic function (e.g. alcohol induced cirrhosis)
• Marasmus (protein & calorie malnutrition)

Answer 28

Loss of hepatic function (e.g. alcohol induced cirrhosis)

Question 29

Which molecule is least oxidized?
alanine
fructose
glucose
oleate
stearate

Answer 29

stearate

Question 30

When a person is burning fat for the majority of his energy, his RQ will be lower than if he were using mostly carbohydrates. This is because fat is more. . .

Answer 30

reduced!

also delicious?

Question 31

A healthy woman ate a meal of mixed carbohydrates, fat and protein on monday evening, then had her respiratory quotient (RQ) measured by indirect calorimetry. She did not eat anything for three days, and had her RQ measured again on Thursday. What happened to her RQ from Monday to Thursday?

Answer 31

DECREASED
Correct answer is ‘decreased’ because she is switching from oxidizing carbs in the fed state to oxidizing fat in the starved state.