Nutrition

Question 1

GI System

Answer 1

extracts chemical energy from food and makes it available for work in tissues

Question 2

Glucose energy content

Answer 2

4 kcal/gram
oxidized for energy
stored as glycogen or TAG
synthesize MANY compounds

Question 3

Fatty acid energy content

Answer 3

9 kcal/gram
oxidized for energy
stored as TAG
synthesis of membrane lipids

Question 4

Amino Acid energy content

Answer 4

4 kcal/gram
oxidized for energy
protein synthesis
synthesis of nitrogen compounds

Question 5

Fed state

Answer 5

lasts 2-4 hrs after a meal

Question 6

Fasted state

Answer 6

overnight without eating
PRIMARILY AA metabolism
Glucagon is released and binds to its receptor, causing activation of AC –> cAMP –> activation of PKA –> phosphorylates things that were dephosphorylated by PP1

Question 7

Starved state

Answer 7

prolonged fasting

Question 8

Hypercatabolic state

Answer 8

trauma, sepsis, etc

not related to meals

Question 9

Teleological statement

Answer 9

after eating, body wants to store calories that exceed its immediate energy needs so it can withstand nutrient unavailability periods

Question 10

Mechanistic statement

Answer 10

nutrients stimulate release of specific hormones that upregulate biosynthetic pathways in different tissues

Question 11

Insulin

Answer 11

Most important hormone regulating storage pathways in fed state
Released from pancreatic beta cells –> directly responsive to [ ] of glucose in blood
Inhibits release of glucagon –> which is major regulator of catabolism in fasted state

Question 12

Insulin released?

Answer 12

proportional to amount of carbs in meal
high carbs = high insulin
high protein = low insulin

Question 13

Insulin receptor

Answer 13

tyrosine kinase –> 2 pathways

1. MAPK –> increases transcription
2. PKB –> PP1 –> dephosphorylates

Question 14

Liver

Answer 14

primary organ responsible for maintaining glucose homeostasis
After eating carb meal…..
1. biosynthetic pathways that produce glucose are inhibited
2. metabolic pathways that store glucose are activated

Question 15

Brain

Answer 15

oxidizes glucose to O2 to make ATP

Question 16

RBCs

Answer 16

ferment glucose to pyruvate –> exports lactate

Question 17

White adipose cells

Answer 17

ferments glucose to glycerol 3-phosphate –> backbone for TAG

Question 18

Muscle

Answer 18

Skeletal muscle –> glycolysis, FA beta-oxidation, glycogenolysis
Cardiac Muscle –> FA beta-oxidation, oxidation of glucose and lactate

Question 19

Gut

Answer 19

intestinal epithelial cells –> convert gluatmine, glutamate, and aspartate to alpha-ketoglutarate

Question 20

Liver response to fasting

Answer 20

increases production/export of glucose for use by other tissues
ATP to power gluconeogenesis is expensive and comes from FA beta-oxidation
Acetyl CoA produced by FA beta-oxidation is substrate for ketone bodies

Question 21

Muscle response to fasting

Answer 21

Skeletal muscle –> proteolysis produces AA, branched chain AA are used by muscle
Cardiac muscle –> FA beta-oxidation increases, glycolysis decreases

Question 22

Gut response to fasting

Answer 22

Gut epithelial cells rely on glutamine, glucose, and BCAA from blood

Question 23

Adipose response to fasting

Answer 23

lipolysis to TAG produces FAs and glycerol

Question 24

Prolonged fasting responses

Answer 24

Lipolysis increases in adipose tissue
Liver increases production of ketone bodies
Ketone body utilization by skeletal muscle decreases and ketone body utilization by brain increases
Cardiac muscle uses FAs
Skeletal muscle breaks down

Question 25

What happens to urea cycle during prolonged fasting?

Answer 25

decreases because body stops using AA metabolism, so less nitrogen produced

Question 26

Hypercatabolism

Answer 26

rapid mobilization of stored fuels to provide energy for wound repair and immune system function
- characterized by sustained muscle and organ protein breakdown

Question 27

Epinephrine

Answer 27

activates hormone sensitive lipase –> FAs mobilized from adipose tissue

Question 28

Cortisol

Answer 28

activates muscle proteolysis –> AA mobilized from muscle

Question 29

Glucagon

Answer 29

activates hepatic glycogenolysis and gluconeogenesis

Question 30

Organ response to hypercatabolism

Answer 30

maintaining POSITIVE NITROGEN BALANCE is nutritional goal for all recovering patients
Nitrogen Balance = nitrogen intake - (urinary urea nitrogen + 2)
0.16 g of N/ 1 g of protein

Question 31

Creatine

Answer 31

synthesized in kidney and liver, serves as buffer of high energy phosphate bonds to replenish ATP in skeletal, cardiac and brain
- breakdown product is creatinine and is not metabolized –> gets excrete in urine (constant excretion and proportional to muscle mass)

Question 32

Creatinine-Height Index

Answer 32

measure of nutritional status –> measured over 24 hrs

100% is “normal”

Question 33

Basic Metabolic Rate

Answer 33

kcal/day

measured under standardized conditions

Question 34

Resting Metabolic Rate

Answer 34

kcal/unit of time

measured under less standardized conditions

Question 35

Resting Energy Expenditure

Answer 35

kcal/day

RMR + TEF

Question 36

Total Energy Expenditure

Answer 36

kcal/day

REE plus energy expended in physical activity, wound repair, etc

Question 37

Indirect Calorimetry

Answer 37

RQ = volume of CO2 exhaled/volume of O2 inhaled

Question 38

Fat RQ

Answer 38

lowest ~ 0.7

least oxidized dietary fuel –> more O2 inhaled for each CO2 exhaled

Question 39

Protein RQ

Answer 39

oxidation state in between carb and fat

RQ ~ 0.8

Question 40

Carb RQ

Answer 40

highest ~ 1.0
most oxidized dietary fuel
requires less O2 inhaled for each CO2 exhaled