MMT: metabolic fuels

Question 1

List the four common dietary fuels.

Answer 1

carbs, fats, proteins, alcohol

Question 2

Describe how dietary carbohydrates are processed and absorbed.

Answer 2

• amylase (salivary and pancreatic) begin to break down polysaccharides
• disaccharidases in the small intestine break down disaccharides into monosaccharides.
• we can absorb and use the monosaccharides!

Question 3

Describe the fates of glucose in the liver after a meal.

Answer 3

Forming glycogen for stored energy, making fatty acids, making cholesterol/lipids, making amino acids

Question 4

describe what dietary fuel(s) the brain uses

Answer 4

major consumer of glucose, 120-150 mg a day. Cannot use fatty acids for energy, making their primary source glucose. They can use ketone bodies under fasting conditions

Question 5

describe what dietary fuel(s) RBCs uses

Answer 5

RBCs can only use glucose for energy, largely because they have no mitochondria and thus can’t process ketone bodies, fatty acids, or ethanol

Question 6

describe what dietary fuel(s) skeletal muscle uses

Answer 6

can use glucose and fatty acids. Uses glycogen when glucose is low, and makes glycogen when glucose is high

Question 7

Describe the fates of dietary amino acids

Answer 7

We cannot store amino acids; we use them to make proteins, heme, hormones, neurotransmitters, purine and pyrimidine bases, ketone bodies, and glucose if needed

Question 8

what is kwashiorkor disease

Answer 8

taking in enough calories but not enough protein. This causes significant edema in the abdomen

Question 9

what is marasmus

Answer 9

not taking in enough calories; emaciated and developmental delays

Question 10

State the products of ethanol metabolism.

Answer 10

Ethanol > acetaldehyde > acetate

Question 11

Explain why more energy can be stored as fat than as glycogen.

Answer 11

Oxidizing carbons! Because of this, fat has slightly more potential for energy than carbs

Question 12

Explain the role of liver glycogen in buffering blood glucose.

Answer 12

Insulin promotes forming glycogen, glucagon promotes breaking down glycogen; the amount of glucose in the blood stream can be altered via building or breaking glycogen in the liver

Question 13

Summarize the metabolic fates of carbohydrates, fats, and proteins during the fed state.

Answer 13

Fats: fats get stored in adipose tissue

Glucose: muscle uses glycogen for its own purpose, liver uses it to buffer our blood glucose

Proteins: used to make other proteins, but cannot be stored

Question 14

Specify the 3 non-carbohydrate sources utilized for gluconeogenesis.

Answer 14

Lactate, glycerol, glucogenic amino acids

Question 15

What cells do or don’t need insulin to bring glucose into their cells?

Answer 15

Skeletal muscle cells and adipose tissue require insulin for uptake of glucose

BRICKLIPS (brain, RBCs, intestine, cornea, kidneys, liver, islet beta cells, placenta, and spermatocytes) do not require insulin to take glucose into the cell

Question 16

What is VLDL

Answer 16

Lipoprotein particles that take lipids out of the liver to various tissues

Question 17

Which two amino acids are strictly ketogenic?

Answer 17

Leucine and lysine

Question 18

When we have an ischemic event, what is the only fuel source we can use?

Answer 18

Glucose

Question 19

describe what happens with various metabolic fuels in the fed state

Answer 19

-glucose goes into the liver to make glycogen, triglycerides, or energy. These are insulin dependent. Also goes to the brain, red blood cells, and skeletal muscle. Glucose will be used for energy and storage in skeletal muscle

-fat gets released in chylomicrons and can be stores in adipose

-proteins can be used to make other proteins and biomolecules. Otherwise, it is used for energy

Question 20

describe what happens with various metabolic fuels in the brief fasting state

Answer 20

-glucose: glucagon rises to break down glycogen to create free glucose. The glucose can then be used in the brain and red blood cells

-fats: triglycerides get broken down. The glycerol backbone re-enters the blood stream and the fatty acids can be used by the tissues. Some ketone bodies can be made from these in the liver.

-Protein: used to make energy

Question 21

describe what happens with various metabolic fuels in the prolonged fasting state

Answer 21

-Glucose: very low levels. Glycogen stores are gone. Any remaining glucose is saved for red blood cells.

-Fats: major source of energy; used in skeletal muscle primarily, also brought to the liver to produce ketone bodies, which will be used by the brain

-Proteins: we barely break these down