Energy Metabolism

Question 1

what is the cellular source of energy

Answer 1

ATP

Question 2

what does ATP do/ where does it come from? `

Answer 2

• sustains physical energy, anabolism, active transport

- supplied by the macronutrients in the diet

Question 3

how many chemistry calories are in a food calorie

Answer 3

1000 chemistry calories = 1 food calorie

Question 4

how many KJs are in 1 food calorie

Answer 4

1 food calorie = 4.18 KJ

Question 5

describe positive energy balance

Answer 5

• weight gain/ obesity
• infertility
• increased blood lipids
• insulin resistance

Question 6

describe negative energy balance

Answer 6

weight loss

• infection
• loss of performance
• reduced bone mass

Question 7

what did Antoine Lavoisier do?

Answer 7

• compared heat produced by a genie pot with the production of co2
• ice calorimeter (heat produced estimated by the amount of ice that melts
• CO2 formed from the reaction between oxygen and organic matter

Question 8

what did Justin Liebig recognize?

Answer 8

Justin Leigib recognized that protein, carbohydrates, and fats are oxidized by the body

Question 9

what did max rubner do?

Answer 9

max rubner measured energy values of certain foods to determine caloric content

Question 10

what is calorimetry

Answer 10

it is the measurement of heat production

- uses heat as an indicator of the amount of energy stored in the chemical bonds of food

Question 11

what are the steps when carrying out bomb calorimetry

Answer 11

1. dry and weight sample and place in enclosed chamber- with oxygen
2. ignite the sample
3. heat released is absorbed by the water and measured

Question 12

what are the potential sources of error in terms of bomb calorimetry

Answer 12

• overestimate energy (we dont digest like a bomb calorimeter)
• doesn’t take into account energy needed for digestion/ absorption

Question 13

what is the Atwater value for CHO

Answer 13

4 kcal/g

Question 14

what is the Atwater value for fat

Answer 14

9 kcal/g

Question 15

what is the Atwater value for protein

Answer 15

4kcal/g

Question 16

what are Atwater values

Answer 16

physiological fuel values

- take into account incomplete digestion

Question 17

why does fat provide more kcal per gram vs CHO or protein

Answer 17

the chemical structure of CHO, fat, and protein indfluence the heat combustion for macronutrients

Question 18

describe the chemical structure of CHO

Answer 18

ratio of hydrogen to oxygen= 2:1

Question 19

describe the chemical structure of protein

Answer 19

• has nitrogen, which contributes to gross energy

however, our bodies dont use nitrogen for energy

Question 20

describe the chemical structure of lipids

Answer 20

• less oxidized than CHO and protein
• ratio of hydrogen to oxygen I much greater than 2:1
• lipids have lots of hydrogen atoms available for cleavage and oxidation for energy

Question 21

what does the bomb calorimeter measure

Answer 21

the bomb calorimeter measures gross energy of a compound

Question 22

what are the factors that affect heat combustion of fatty acids

Answer 22

• unsaturation (the more double bonds, the less energy provided by that molecule)
• chain length (the longer the chain, the more energy provided)

Question 23

what is the heat increment of feeding (HIF)

Answer 23

• thermic effect of food
• energy used for digestion, absorption, distribution, and storage of nutrients
• is about 5-30% of daily energy usage
• used to determine net energy

Question 24

what is net energy

Answer 24

net energy= metabolized energy - HIF

- supports basal metabolism, physical activity, growth, pregnancy, etc

Question 25

how much energy is partitioned towards HIF

Answer 25

5-30% of the metabolized energy is used for basic digestion mechanisms

Question 26

what are the 4 primary components to energy expenditure?

Answer 26

1. basal metabolic rate (BMR) 2. Thermic effect of food (HIF) 3. physical activity energy expenditure (PAEE) 4. thermoregulation (a minor contribution)

Question 27

what tissued are most reflective of the BMR

Answer 27

muscle and bone

Question 28

what is the equation used when calculating BMR

Answer 28

BMR= A * [M^0.75] kcal/day - A= metabolically active tissue (for humans, A=70) - M = body weight in Kg

Question 29

what is kleibers law

Answer 29

(0. 75) | - a constant used for all vertebrates, invertebrates, and unicellular organisms when calculating BMR

Question 30

what are the factors that can affect BMR

Answer 30

- genetics - age - sex - tissue proportions - temperature

Question 31

how does genetics affect BMR

Answer 31

inheritance of a fast or slow metabolic rate

Question 32

how does exercise affect BMR

Answer 32

exercise changes body tissue proportions | muscle uses more energy than fat

Question 33

what does indirect calorimetry measure?

Answer 33

O2 intake, CO2 output | - energy- releasing reactions in the body depends on the use of oxygen

Question 34

what does direct calorimetry measure?

Answer 34

Heat output | - measures the heat a person generates (total heat loss)

Question 35

what is the issue with indirect calorimetry?

Answer 35

this method can not account for anaerobic processed (ie- production of lactic acid) - hyperventilation - masks are impractical

Question 36

what is the issue with direct calorimetry

Answer 36

- expensive | - impractical

Question 37

compare direct vs indirect calorimetry

Answer 37

<1% difference | very comparable

Question 38

what is the respiratory quotient (RQ)

Answer 38

a ratio of metabolic gas exchange provides information about: - energy expenditure - biological substrate being oxidized

Question 39

what is the equation used when calculating RQ (respiratory quotient)

Answer 39

RQ= (CO2 produced)/(O2 consumed)

Question 40

why do RQ values for macronutrients vary

Answer 40

differentiations in chemical composition mean that each macronutrient required a different amount of oxygen intake in relation to CO2 produced ie- fats require almost three times as much oxygen (in comparison to carbs) to complete the digestion