Version 2007
Dr. Puntarica Suwanprathes
1) Thermodynamics
2) Caloric value of Food
3) Caloric equivalent of Oxygen
4) Respiratory Quotient (R)
5) Metabolic pool
6) Calorimetry
7) Metabolic rate (MR)
8) Basal metabolic rate (BMR)
Energy Balance
Thermodynamics
“Law of conservation of energy”
chemical bonds
High energy bond
inorganic
muscle contraction
nerve impulses
secretion
absorption
growth
etc.
inorganic
ATP
(adenosine triphosphate)
net processes
Metabolism
(change)
energy
Where does the chemical energy
come from?
ECF
metabolic pool
cell
Chemical energy
Transformation of Energy
1
FOODS
Chemical energy
in ECF:
metabolic pool
Electrical energy
Mechanical energy
Osmotic energy
Chemical energy
“Work energy”
2
Chemical energy
in ECF:
stored energy
Liver
Muscle
Fatty tissue
Thermal energy
Energy unit
standard unit for Heat energy: calorie (cal.)
1 cal = heat that increase temp. of
1 gm H2O 1 oC
Heat
e.g. from 15 oC to 16 oC
c = gram calorie or standard calorie
Physiology
Kilogram-calorie or Kilocalorie ***
Kcal or Cal or C
1 Kcal = 1000 cal
1 Kcal = 4187 Joules
Metabolic rate
“MR”
= energy release per time unit
Kcal / min
Kcal / hr
Kcal / day
Caloric value of Food
Caloric equivalent of Oxygen
Respiratory Quotient
Energy balance
Caloric value of Food
Bomb Calorimeter
Temp.
volume
p.589
“Caloric value of Food”
Cal/gm (food)
O2
Caloric value of Food
Energy (Cal/gm-food)
Carbohydrate
Bomb
calori
meter
Human
oxidation
Physiologic
value
4.1
4.1
4
?
Protein
5.4
4.2
4
Lipid
9.3
9.3
9
Ethanol
7.1
7.1
7
Caloric requirement
@steady state:
food intake
•age
•gender
•size
•activity
= energy expenditure
sedentary:
2800 Cal/day
labor:
3600 Cal/day
Caloric equivalent of Oxygen
use O2 1 Liter
energy ?
(Cal / L. O2)
Example: Glucose
C6 H12 O6 + 6O2
Glucose
1 Mole
6CO2 + 6H2O + 686 Cal
oxygen
6 Mole
686 Cal (Heat)
(1 Mole = 22.4 Liters)
6 Mole = 6 x 22.4 Liters
= 134.4 Liters
1 Liter O2
686 Cal = 5.10 Cal / L. O )
2
134.4 Liters
Caloric equivalent of Oxygen
water
Lipid
(4.58 Cal / L. O2)
Protein
(4.5 Cal / L. O2)
Vitamin & mineral
Carbohydrate
(5.10 Cal / L. O2)
***Mixed food: 4.825 Cal / L. O2
Caloric equivalent of Oxygen
“mixed food”
Caloric equivalent of O2 = 4.825 Cal / 1 L. O2
VO2
? Cal (Heat)
_____
“Closed-circuit technique”
Respiratory Quotient
food + ? O2
oxidation
? CO2 + ? H2O + ? Cal
CO2 production
O2 consumption
CO2 production
=
O2 consumption
Respiratory Quotient
“RQ”
CO2 production
=
O2 consumption
=
VCO2
VO2
Carbohydrate
1
Protein
0.8
Lipid
0.7
Mixed diet
0.85
Energy balance
“Thermodynamics”
foods
energy input = energy output
chemical energy = heat + work
+ stored chemical energy
−
+ stored energy
− stored energy
positive energy balance
negative energy balance
4 factors
chemical energy = heat + work 2
1
+ stored chemical energy
−
Standard setting:
1 post absorptive state
= 12-14 hrs after meal
2
no voluntary movements
= at rest (physical and mental resting,
but not sleeping)
“Basal state”
@Basal state
- stored chemical energy = heat
*** at rest, 12-14 hrs after meal
using chemical energy
in ECF: metabolic pool
Heart pumping
breathing
Brain activities
Heat
production
energy
“Heat production”
1. Direct calorimetry
2. Indirect calorimetry
Direct calorimetry
Human calorimeter
Thermometer
H2O
chamber
evaporation
Oxygen
radiation
insulators
H2O
CO2
H2O
absorb
absorb
absorb
Heat of evaporation
1 gm H2O
0.58 Kcal
Indirect calorimetry
Caloric equivalent of O2
***mixed food: 4.825 Cal / L. O2
Indirect calorimetry
O2
- stored chemical energy = heat
“O2 consumption”
1 liter O2
Heat ~ 4.825 Kcal
glucose
fat or
protein
1 liter O2
Heat ~ 4.825 Kcal
KNOW: O2 consumption
in time unit
metabolic rate
= VO2 (4.825)
@ rest
Oxygen consumption ~ 250 ml/min
or ~ 15 L/hr
1 liter O2
in 1 hour:
Heat ~ 4.825 Kcal
= 15 L /hr
x 4.825 Kcal
= 72 Kcal /hr
Indirect calorimetry
1. Closed-circuit technique
Lab
2. Opened-circuit technique
Closed-circuit technique
VO2
Benedict-Roth spirometer
Benedict-Roth spirometer
p.593
6 min
normal breathing
100%
? mm
X
(20.72 ml O2 /mm)
= _____ ml/ 6 min
= x10 (_____) ml/ hr
20.72 ml O2 /mm (paper)
X ml/hr
Oxygen consumption = ___
VO2
x STPD factor (Appendix IV)
X L /hr
____
@ STPD
1 liter O2
in 1 hour:
Metabolic rate
Heat ~ 4.825 Cal
(mixed food, RQ=0.82)
= VO2 X Caloric equivalent of O2
= VO2 X 4.825 / L. O2
= ____ Cal /hr
=…? Cal / hr
x STPD factor (Appendix IV)
volume
? mm
time
1 mm = 20.72 ml
1 cm
= 1 min
? mm
6 min
Metabolic rate
Basal Metabolic rate
O2 consumption
ml / unit time (@ATPS)
X
(STPD correction factor)
@STPD
(dry gas, O oC, 760 mmHg)
(Standard Temperature and Pressure, Dry)
Caloric equivalent of O2 = 4.825 Cal / L. O2
MR = O2 consumption (@STPD) x 4.825
Metabolic rate: MR
Basal Metabolic rate: BMR
normal?, high?, or low?
Compare with
“Standard value”
Standard condition
“Basal state”
Basal Metabolic rate: BMR
Basal Metabolic rate: BMR
Report
%
Normal range:
+ 15 % of normal value
+ = higher than normal value
- = lower than normal value
***Note: age, gender
Basal Metabolic rate: BMR
Unit: Kcal / m2 / hour
“Body Surface Area”
BSA
Body surface area: BSA
weight (kg)
height (cm)
BSA (m2) = 71.84 x W0.425 x H0.725
Nomogram
Nomogram
“Dubois Body surface chart”
1.7
50
50
50
50
50
I
III
weight
1.4
BSA
140
(cm)
1.5
height
150
(m2)
1.6
II
(Kg)
160