Whole-Animal Metabolism
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Transcript of Whole-Animal Metabolism
Whole-Animal Metabolism
Animals require chemical energy for:• activity (muscular work)• synthetic activities• heat production (in endotherms)
How can we determine how much energy anorganism requires and uses for these activities?
Look at heat production:
Burn 1 mol (180g) of glucose in a calorimeter*:
1 mol glucose + 6 mol O2 6 mol CO2 + 6 mol H2O +686 kcal (heat)
Metabolize 1 mol of glucose aerobically in an animal:
1 mol glucose + 6 mol O2 + 38 mol ADP + 38 mol Pi 6 mol CO2 + 42 mol H2O + 38 mol ATP + 423 kcal heat
266 kcal
www.umr.edu/-gbert/animation.html
Eventually, all the chemical energy in theorganism will be released as heat -
regardless of the food source.
Therefore, Rate of heat production = Metabolic rate = Em
Holds for all organisms that are not growing
Again, assuming an organism is respiringaerobically, what alternative measures
might we use to approximate the metabolic rate?
Hint:
1 mol glucose + 6 mol O2 + 36 mol ADP + 36 mol Pi 6 mol CO2 + 42 mol H2O + 36 mol ATP + 423 kcal
Answer?
Oxygen consumption
Carbon dioxide expiration
Carbohydrates C6H12O6 + 6 O2 6 CO2 + 6 H2O
Ratio of CO2 prod. / O2 consumed = respiratory quotient = R.Q.
Fat 2 C51H98O6 + 145 O2 102 CO2 + 98 H2O
R.Q. = 102 CO2 / 145 O2 = 0.70
ProteinR.Q. = 0.80
R.Q. = 6 CO2/ 6 O2 = 1.00
Oxygen/carbon dioxide relationships
1 Joule = 0.239 cal
Kcal/liter O2______
5.0 4.7
4.5
if you wish, you can use 4.8 kcal • l O2-1)
Assumes a mixed diet
• size• temperature & season• hibernation & torpor• salinity• photoperiod & tidal cycle• pressure of oxygen• activity
Numerous physical and behavioral factorsaffect metabolic rate:
Definitions:
Basal metabolic rate (BMR) - minimal rate of metabolism
for a fasting, inactive individual (with no heat prod.for homeotherm).
Standard metabolic rate (SMR) - rate for an individualat rest at a given temperature.
Active metabolic rate (AMR) - rate for forced, maximalactivity at a given temperature.
Activity vs. VO2
•
Locomotion is expensive:
In humans, VO2 can increase 15-20 X during exercise
In insects, VO2 can increase 50-200 X during flight:•
activity (e.g. swimming speed)
VO2’•
SMR
Metabolic Scope for Activity = AMR / SMR
Goldfish (ml O2 • kg-1 • h-1)
280
40
VO2’•
Temp. (°C)
0 40
AMR
SMR
Expressed as dimensionless value (e.g., 8)
Cost of Locomotion
VO2 liters O2 • kg-1 • h-1
C.L. = = = liters O2 • kg-1 • km-1
velocity km • h-1
•
C.L.
Salmon
velocity (lengths • s-1)0 1 2 3 4
C.L.
Body Mass (kg)
0.1 1 10 100 1000 10000
runningflying
swimming