Biochem

Question 1

Daily Energy Expenditure

Answer 1

The components of the DEE are basal metabolism, physical activity, and the thermic effect of food.

Question 2

Basal metabolism expressed as

Answer 2

Basal Metabolic Rate (BMR) or the closely related Resting Metabolic Rate (RMR).

Question 3

Basal metabolism includes

Answer 3

the energy needed to sustain cellular and organ function while at rest.

Question 4

factors that affect BMR

Answer 4

Gender, body temp, environmental temperature, thyroid hormone, reproduction, age

Question 5

DIT/TEF

Answer 5

The energy required to digest, absorb, distribute and store nutrients is referred to as diet induced thermogenesis (DIT) or the thermic effect of food (TEF).

BMR x 0.1

Question 6

DEE

Answer 6

Daily Energy Expenditure (DEE) kcal/day

DEE is the REE plus energy expended in physical activity, wound repair, etc.

Question 7

RQ

Answer 7

volume CO2 exhaled/ volume O2 inhaled

Question 8

Fat = _______ oxidized fuel, requires more/less O2, RQ = _____

Answer 8

LEAST
most reduced
Requires MORE o2 inhaled for each CO2 exhaled
RQ = 0.70

Question 9

Protein = _______ oxidized fuel, requires more/less O2, RQ = _____

Answer 9

intermediate

RQ = 0.8-ish

Question 10

Carbs = _______ oxidized fuel, requires more/less O2, RQ = _____

Answer 10

MOST oxidized (lease reduced)
Requires LESS O2 per CO2
RQ highest = 1.0

Question 11

4 important metabolic states

Answer 11

Fed (2-4 hours after meal)
Fasted (overnight w/o eating)
Starved (prolonged fasting)
Hypercatabolic (trauma, sepsis, etc.)

Question 12

What body wants in fed state

Answer 12

After eating, the body wants to store calories that exceed its immediate energy needs, so that it can withstand periods of nutrient unavailability. The body stores excess calories as carbohydrate, fat, and protein.

Question 13

Mechanistically what happens in fed state

Answer 13

After eating, nutrients stimulate the release of specific hormones, such as insulin, that upregulate biosynthetic pathways in different tissues.

Question 14

Most important hormone regulating storage pathways in fed state

Answer 14

insulin

Question 15

insulin release from ___ in response to ____

Answer 15

Insulin release from pancreatic beta cells is directly responsive to the concentration of glucose in the blood.

Question 16

Insulin inhibits release of

Answer 16

glucagon, the major regulator of catabolism in the fasted state.

Question 17

Relative amount _____ in meal determines ratio of _____ to _____

Answer 17

CARBS
Insulin to glucagon

ie. high carbs –> more insulin

Question 18

liver response to carb meal

Answer 18

inhibit biosynthetic pathways that produce glucose (glycogenolysis, gluconeogenesis)

activate metabolic pathways that store glucose

Question 19

liver response to protein meal

Answer 19

elevated amino acids in blood –> glucagon (pancreatic alpha cells) –> AA used for gluconeogenesis

Question 20

brain response to feeding

Answer 20

oxidizes glucose to CO2 to make ATP through OP

Question 21

RBCs response to feeding

Answer 21

Ferments glucose to pyruvate, exports lactate

Question 22

White adipose cells response to feeding

Answer 22

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

Question 23

skeletal muscle response to feeding

Answer 23

Glycolysis, fatty acid beta oxidation, glycogenogenesis, protein synthesis

Question 24

cardiac muscle response to feeding

Answer 24

Fatty acid beta oxidation (60-80%); Oxidation of glucose and lactate (20-40%).

Question 25

intestinal epithelial cells response to feeding

Answer 25

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

Question 26

colonocytes response to feeding

Answer 26

Use short chain fatty acids produced by gut bacteria.

Question 27

what body wants during fasting

Answer 27

In between meals, the body wants to mobilize stored energy so that it can continue to perform work.

Question 28

mechanistic during fasting

Answer 28

Low carbohydrates in the blood promote the release of glucagon, a major regulator of hepatic fuel mobilization, from pancreatic alpha cells. Furthermore, intracellular enzymes that activate fuel mobilization pathways are directly regulated by energetic imbalance. E.g., AMP-K.

Question 29

Glucagon binding to receptor causes

Answer 29

causes activation of adenylate cyclase, production of cAMP, and activation of PKA.

Question 30

REE and BMR are measured in ______ state

Answer 30

fasted

Question 31

liver response to fasting

Answer 31

increases production of export and glucose for use by other tissues
glycogenolysis, gluconeogenesis

Question 32

gluconeogenesis uses ______ to produce glucose

Answer 32

carbon skeletons from amino acids, lactate, and glycerol

Question 33

ATP to power gluconeogenesis comes from

Answer 33

FAD2H, NADH reduced by FA b-ox

Question 34

acetyl CoA produced by FA b-ox is a substrate for

Answer 34

ketone body synthesis

Question 35

skeletal muscle response to fasting

Answer 35

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 by the liver.
As the fast prolongs, skeletal muscle can use ketone bodies for energy.

Question 36

cardiac muscle response to fasting

Answer 36

Fatty acid beta oxidation increases; glycolysis decreases.

Question 37

Gut epithelial cell response to fasting

Answer 37

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 38

white adipose tissue response to fasting

Answer 38

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

Question 39

what body wants in starvation

Answer 39

mcchickens

During famine, the body preserves body structure by degrading only tissue with the most caloric density (fat) to provide energy.

Question 40

mechanisticly how body responds to starvation

Answer 40

Adipose triacylglycerol is mobilized for fuel and to synthesize ketone bodies; muscle protein breakdown is minimized; glucose is spared for red blood cells.

Question 41

Changes that occur with prolonged fasting

Answer 41

More lipolysis, less muscle breakdown
More ketone bodies - brain uses these, cardiac muscle still uses FAs
Less gluconeogenesis

Question 42

rapid mobilization of stored fuels to provide energy for wound repair and immune system function.

Answer 42

Hypercatabolism

Question 43

hypercatabolism is characterized by

Answer 43

characterized by sustained muscle and organ protein breakdown.

Question 44

hormone responses in hypercatabolism

Answer 44

epinephrine activates hormone sensitive lipase –> fatty acids mobilized from adipose

cortisol activates muscle proteolysis –> amino acids mobilized from muscle

glucagon activates hepatic glycogenolysis and gluconeogenesis

Question 45

hypercatabolism response mediated by

Answer 45

CNS (not nutrient levels in blood)

Question 46

nitrogen balance

Answer 46

= nitrogen intake – (total urinary nitrogen** + 2-4)

Total urinary nitrogen ≈ (total urea nitrogen) / 0.85

2 normal
3 pediatric TPN
4 peds eating normally

Question 47

CHI is a measure of

Answer 47

nutritional state

creatinine height index

Urine creatinine is measured over 24 hours and compared with values obtained from healthy, well nourished subjects.