Lab 2: Metabolic Rate

Question 1

What does the term metabolism reflect?

Answer 1

all chemical and cellular reactions, as well as mechanical work that occurs in living cells

Question 2

What type of reactions yield energy?

Answer 2

catabolic

Question 3

What type of reactions require energy input?

Answer 3

anabolic

Question 4

What is the second law of thermodynamics?

Answer 4

two isolated systems in contact with each other, which differ in any way (temp, density, or pressure) will equalize if given the opportunity

Question 5

How can the rate of heat loss be measured when humans transform energy to do work?

Answer 5

as a reflection of the metabolic rate of an organism

Question 6

How is metabolic rate measured?

Answer 6

direct or indirect calorimetry

Question 7

What variable does a calorimeter measure (and in what unit)?

Answer 7

heat in calories

Question 8

What is a calorie?

Answer 8

the amount of heat required to raise the temperature of 1 gram of water by 1 degree celsius

Question 9

How does a direct calorimeter work?

Answer 9

1) subject placed in chamber surrounded by insulated water jacket
2) thermometers in the water jacket measure temperature changes in the water
3) knowing the specific heat of water ( 1cal/deg*g) and the mass of water in the jacket (g), the heat loss (C) from the subject to the walls of the chamber can be calculated

Question 10

What does the direct calorimeter procedure provide a measurement of?

Answer 10

all heat production in the body including both aerobic and anaerobic metabolism

Question 11

When can indirect calorimetry be used?

Answer 11

when metabolism is predominantly aerobic

Question 12

How does an indirect calorimeter work?

Answer 12

measures oxygen uptake to indirectly determine metabolic rate

Question 13

What factor changes the relationship between oxygen consumption and energy production?

Answer 13

the substrate utilized (carb, fat, or protein)

Question 14

What is open circuit spirometry?

Answer 14

determines the rate of oxygen uptake (VO2) by subtracting the amount of oxygen expired (VEO2) from the amount of oxygen inspired (VIO2)

Question 15

What is the Douglas bag technique?

Answer 15

subject breathes through mouthpiece attached to a two-way valve (Daniel’s valve) that permits the entry of atmospheric air on the inspired side and the removal of expired air through the other

Question 16

How is the volume of expired air collected via the Douglas bag technique?

Answer 16

collected into plastic douglas bags and analyzed for the concentrations of fractional expired oxygen and carbon dioxide using gas analysis machines (PARVO)

Question 17

How is the volume of expired air determined in the douglas bag technique?

Answer 17

using a volumeter

Question 18

How is the inspired minute ventilation calculated?

Answer 18

by assuming the amount of nitrogen inspired equals the amount of nitrogen expired

Question 19

What factors do we need to determine the rate of oxygen consumption?

Answer 19

-volume of expired air (pulmonary ventilation in L/min)
-fraction of expired oxygen (FeO2)
-fraction of expired carbon dioxide (FeCO2)
-room temperature and barometric pressure (required for standardization of different environmental conditions)

Question 20

What variables are always known by the technician when measuring oxygen consumption?

Answer 20

-fraction of inspired oxygen (FiO2) = 0.2093
-fraction of inspired carbon dioxide (FiCO2) = 0.0003

Question 21

How is the expired minute ventilation measured and what problem does it pose?

Answer 21

expired minute ventilation is measured as it comes out of mouth from the lungs, it is saturated with water vapor and is at ambient temperature and pressure (ATPS)

Question 22

To fix the problem posed by minute ventilations collected in Douglas bags, what is done?

Answer 22

all expired minute ventilations collected in a Douglas bag are corrected to a dry gas and standard temperature and pressure (STPD) using a correction factor based on ambient conditions

Question 23

Ve(STPD) =

Answer 23

Ve(ATPS) x STPD correction factor

Question 24

what is gross mechanical efficiency (ME)

Answer 24

the ratio of mechanical power (mechanical work rate) to metabolic power (rate of energy expenditure required to maintain this specific mechanical work rate)

Question 25

normal values of ME for humans

Answer 25

0-30%

Question 26

what does ME depend on?

Answer 26

intensity, exercise modality, contraction type, muscle fiber type, etc.

Question 27

what is the main component of total daily energy expenditure (TDEE)

Answer 27

basal metabolic rate (BMR)

Question 28

what does BMR include? what proportion of TDEE does this account for?

Answer 28

energy used to sustain all cellular, chemical, and mechanical work at rest (60-70% of TDEE)

Question 29

what is the thermic effect of food (TEF)? what proportion of TDEE does this account for?

Answer 29

energy cost for the digestion of food and absorption of nutrients (10% of TDEE)

Question 30

what are the two subcomponents of total daily activity thermogenesis (TDAT)?

Answer 30

exercise activity thermogenesis (EAT) and non-exercise activity thermogenesis (NEAT)

Question 31

what does EAT account for?

Answer 31

the energy expenditure associated with sport-specific exercising

Question 32

what does NEAT account for?

Answer 32

energy cost of all other forms of physical activity

Question 33

what is the dynamic energy balance equation?

Answer 33

rate of change of energy stores = rate of change of energy intake -rate of change of energy expenditure