Topic 65 - Calorimetryc methods, the definition and importance of the respiratory quotient Flashcards
1
Q
Words to include in calorimetryc methods
A
- Direct calorimetry
- Method of Lavoiser and Laplace
- Complex direct caloirmetry
- Compensation calorimetry
- Gradient calorimetry
- Indirect calorimetry
- Open system
- Closed system
Direct calorimetry
- Method of Lavoiser and Laplace
- Chamber
- Animal
- Surrounded by ice
- Heat generation
- Amount of melted ice
- Expired air and evaporation (ø measured)
- Chamber
- Complex direct calorimetry
- Emission of water vapor
- Heat isolated chamber
- Adiabatic calorimeter
- Total heat production
- Water evaporated
- Increase in weight (calculated)
- Water absorbing substances
- Water evaporated
- Compensation calorimeter
- 2 chambers of identical thermal capacity
- Constant temperature
- 1 chamber: animal
- 1 chamber: electric bulb of known output
- Animal heats up chamber = bulb warms up the other chamber for equal temperatur
- 1J = 1Ws (Watt-secundum)
- 2 chambers of identical thermal capacity
- Gradient calorimeter
- Double walled chamber
- Inner wall: heat conducter
- Outer wall: constant temperature
- Heat difference between wall
- Amount of heat dissipated
- Double walled chamber
Indirect calorimetry
- Open system
- Environmental / atmospheric O2 inspired
- Expired air measured
- Douglas bag
- Gas-storing bag
- Exhalation
- Inhalation
- Closed system
- No atmospheric O2 inhaled
- Oxygen added to system
- Amount of consumed O2
Complex indirect and direct calorimetry
- Atwar-Rose Respiratory Calorimetry
- Closed, heat-isolated chamber
- Measure water temperature ↑
- Velocity of water outflow
2
Q
Words to include in respiratory quotient (RQ)
A
- RQ = CO2 [vol./time] / O2 [vol./time]
- Respiratory quotient = respiratory exchange rate
- Range of RQ: 0.7-1.0
- Hyperventilation: RQ ↑ (2.0)
- Metabolic acidosis: RQ ↑
- After exercise: RQ ↓ (0.5)
- Fattening: RQ > 1
- Starving RQ < 0.5
- Oxidized carbohydrate, protein and fat:
- Expired CO2
- Inspired O2
- Qualitiative composition of energy sources
- Chemical reaction of metabolism
- Stoichiometric
3
Q
Calorimetryc methods
Name the different calorimetryc methods
A
-
Direct calorimetry
- Method of Lavoiser and Laplace
- Complex direct calorimetry
- Compensation calorimetry
- Gradient calorimetry
-
Indirect calorimetry
- Open system
- Closed system
- Complex indirect and direct calorimetry (Atwater-Rose respiratory calorimeter)
4
Q
Calorimetryc methods
Direct calorimetry
A
Method of Lavoiser & Laplace
- Chamber containing the animal surrounded by ice
- The amount of melting ice and the water being produced was used to estimate heat generation
-
Disadvatages:__
- Expired air and evaporation off the body are not measured
- High humidity in the chamber
Complex direct calorimetry
- Emission of water vapor from the body
- Water of known temperature enters the outer casing of the heat isolated chamber (containing the animal)
- Heat emitted from the animal heats up the water
- Temperature of the water leaving the casing is measured
- From this value and velocity of flow, heat production can be calculated (adiabatic calorimeter)
Compensation calorimeter
- 2 chambers of identical thermal capacity are connected
- Chamber 1: animal inside
- Chamber 2: electric bulb of known output inside
- Animal heats up tis chamger → the bulb will warm up its chamber to keep the temperature equal in both chambers
- Energy used by the bulb = output of heat produced by animal
- 1 J = 1 Ws (watt-secundum)
Gradient calorimeter
-
Double walled chamber
- Inner wall: good heat conduction
- Outer wall: constant temperature
- The heat difference between the two walls is measured to calculate the amount of heat dissipated
- It detects the heat loss occuring by means of:
- Radiation
- Conduction
- Convection
5
Q
Calorimetryc methods
Indirect calorimetry
A
Open system
- Environmental / atmospheric O2 inspired
- Expired air is measured
-
Douglas bag
- Gas storing bag
- Exhalation
- Inhalation
Closed system
- On atmospheric O2 inhaled
- Oxygen is added to the system
- Indicator directly shows amount of consumed O2
- Advantage of indirect calorimetry:
- Animal can move freely in its natural environment
- Disadvantage of indirect calorimetry:
- Restricted ability to measure the O2-dependant energy production only
6
Q
Calorimetryc methods
Complex indirect and direct calorimetry
A
- Atwar-Rose respiratory calorimeter
- The experimental animal is placed into a closed, heat-isolated chamber. The degree of heat production of the animal can be calculated from data collected by measuring:
- Water temperature ↑
- Velocityof thewater outflow
- O2 consumption and CO2 production of the animal can also be determined
7
Q
Respiratory quotient
A
- Respiratory quotient = respiratory exchange rate
- Definition: the volume of production of CO2 within a time unit divided by the volume of consumed O2 during the same period
- Range of RQ: 0.7 - 1.0
- Hyperventilation: RQ ↑ (2.0)
- Metabolic acidosis: RQ ↑
- After exercise: RQ ↓ (0.5) - paying back of O2 debt
- Fattening: RQ > 1
- Starving: RQ < 0.5
- The amount of oxidized carbohydrate, protein and fat can be approximated from the amounts of:
- Expired CO2
- Inspired O2
- Nitrogen excretedin theurine
- RQ values can provide information about the qualitative composition of energy sources (carbohydrate, protein & fat)
- Chemical reactions of metabolism are stoichiometric