LESSON 7 - energy expenditure Flashcards
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all metabolic processes ultimately result in _____ production
heat
what are the two outcomes of substrate metabolism efficiency ?
ATP and heat
what percentage of substrate energy is ATP ?
40%
what percentage of substrate energy is heat ?
60%
what essentially defines metabolic rate ?
heat
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_______ production rate from cells, tissues, and the whole body operationally defines metabolic rate
heat
when does heat production increase ?
with energy production
what represents the basic unit of heat measurement ?
calorie (kcal)
what refers to measurement of heat transfer ?
calorimetry
what is a kilocalorie ?
unit of energy
what is the amount of heat energy needed to raise the temperature of 1 kg of water by 1 degree Celsius ?
kilocalorie
1 kcal =
4.184 kilojoules
how do we measure a kilocalorie ?
measured with bomb calorimeter
is oxygen highly flammable ?
yes
what will give us an indicator of energy expenditure ?
how much heat is released
what occurs within the sealed thick walled reaction chamber ?
energy is transferred into the water so the surrounding water absorbs the heat from the combustion
1g = how many calories ?
4 calories
1g = how many proteins ?
4 calories
1g = how many fats ?
9 calories
what are the two ways we quantify human energy expenditure ?
indirect and direct calorimetry
what is indirect calorimetry ?
- O2 uptake and CO2 production
- how heavy their breathing
what is direct calorimetry ?
- heat
- direct measure of how hard someone is working
what type of calorimetry measures heat production ?
direct calorimetry
what type of calorimetry measures oxygen consumption and carbon dioxide production ?
indirect calorimetry
what are the three indirect heat measurements ?
- O2 uptake
- CO2 production
- N2 balance
what is a human calorimeter ?
direct measure of heat production and thus kcal expended
is a human calorimeter indirect or direct ?
direct
does measuring a persons rate of oxygen uptake provide an indirect or direct (but accurate) estimate of energy expenditure ?
indirect
what are the two types of indirect calorimetry ?
closed-circuit and open-circuit spirometry
is it indirect or direct which measures the uptake/consumption of oxygen from the product side of the catabolic reaction ?
indirect
what is closed-circuit spirometry ?
how much volume of O2 has gone down
rate of volume reduction =
VO2 in L/min
what does the open-circuit spirometer measure ?
inspired and expired O2 volume
magnitude of difference divided by time =
VO2 in L/min
what is the term defined as “oxidative metabolism of glucose and fat uses O2 and produces CO2 and water”
indirect calorimetry
energy expenditure can be estimated by measuring what two variables at the mouth ?
VO2 and CO2 inspired and VO2 and CO2 expired
what is the formula for indirect calorimetry rate ?
difference in volume divided by time = rate
what are the two formulas we are “familiar” with ?
oxygen uptake (L/min) and carbon dioxide production (L/min)
what is Douglas bag VO2 ?
calculation for estimating O2 uptake (VO2) during exercise in normoxia
to estimate the amount of energy used by the body what is necessary ?
to know the type of food substrate being oxidized
what does the amount of O2 used during metabolism depend on ?
the type of fuel being oxidized
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we can use VCO2 and VO from indirect calorimetry to determine __________ and __________
substrate utilization and quantify energy expenditure
between fat and carbs which require more oxygen for ATP ?
more ATP per oxygen in glucose
between fats and carbs which would you prefer in regards to oxygen consumption ?
prefer carbs since you need more O2 to break up fatty acids
what is the average RER for fats ?
0.70
what is the average RER for carbs ?
1.00
what is better for RER in regards to oxygen ? higher or lower number ?
higher number (the more its being oxidized)
between fats and carbs which is the less efficient storage of energy ?
carbs
between carbs and fats which is more kcal dense ?
fat
between carbs and fats which is less kcal dense ?
carbs
what does RER stand for ?
respiratory exchange ration
what is RQ ?
cell respiration
what is RQ and RER ?
the same measurement but are obtained differently
what is the maximal range of RQ ?
0.70 to 1.00
what is the maximal range of RER ?
<0.70 to >1.20
how many scenarios are there where RER and RQ may not equal each-other ?
4
name the four scenarios where might RER not equal RQ ?
- hyperventilation
- metabolic acidosis
- non-steady state exercise
- prolonged exercise
define hyperventilation :
excrete CO2 to increase O2
define metabolic acidoses :
- respiratory compensation
- maintain nice level of pH
- kidney failure
define non-steady state exercise :
- VO2 varies
- steady state = keeping a steady pace (marathon ex)
what scenario is it when
“increases CO2 output in excess of metabolically produce CO2; increased VCO2”
hyperventilation
what scenario is it when
“buffering of H ions via bicarbonate yields additional, non metabolic CO2 which is also breathed out at the mouth ; increased VCO2”
metabolic acidosis
what scenario is it when
“VCO2 takes longer to attain steady-state compared to VO2 at exercise onset; temporal distortion”
non-steady-state exercise
what scenario is it when
“if CHO nutrition is poor and glycogen stores low, longer exercise duration could result in a amino acid oxidation”
prolonged exercise
what scenario is RER > RQ ?
hyperventilation
what scenario is RER > 1.0 ?
metabolic acidosis
what scenario is RER < RQ ?
non-steaduy-state exercise
what scenario is RER doesn’t equal RQ ?
prolonged exercise
what is the term used to define
“the rate at which the body used energy or the rate at which ATP must be resynthesized to satisfy bodily demand”
metabolic rate
what two things work interchangeably? if were measuring ____ ; were measuring _________
VO2 and metabolic rate
what does BMR stand for ?
basal metabolic rate
what is BMR ?
the minimal amount of energy required to carry out essential physiological functions
what is the formula for measuring energy balance for BMR ?
energy intake - energy output = energy balance
what is energy intake in regards to calories ?
calories consumed
what is energy output in regards to calories ?
calories extended
if we have a positive energy balance what does this mean ?
increased body mass
if we have a negative energy balance what does this mean ?
decrease body mass
what type of energy balance is “storing more energy than released”
positive
what type of energy balance is “ used more than we have taken in/mass will fall”
negative
