Whole-Animal Metabolism Animals require chemical energy for: activity (muscular work) synthetic activities heat production (in endotherms) How can we determine how much energy an organism 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 the organism 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

Carbon dioxide expiration Again, assuming an organism is respiring aerobically, 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

Oxygen/carbon dioxide relationships Ratio of CO2 prod. / O2 consumed = respiratory quotient = R.Q. Carbohydrates C6H12O6 + 6 O2 6 CO2 + 6 H2O R.Q. = 6 CO2/ 6 O2 = 1.00 Fat 2 C51H98O6 + 145 O2 102 CO2 + 98 H2O R.Q. = 102 CO2 / 145 O2 = 0.70 Protein R.Q. = 0.80

if you wish, you can use 4.8 kcal • l O2-1) 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

Numerous physical and behavioral factors affect metabolic rate: size temperature & season hibernation & torpor salinity photoperiod & tidal cycle pressure of oxygen activity

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 individual at rest at a given temperature. Active metabolic rate (AMR) - rate for forced, maximal activity at a given temperature.

Locomotion is expensive: • 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 activity (e.g. swimming speed)

Expressed as dimensionless value (e.g., 8) Metabolic Scope for Activity = AMR / SMR Expressed as dimensionless value (e.g., 8) Goldfish (ml O2 • kg-1 • h-1) 280 40 VO2’ • Temp. (°C) 0 40 AMR SMR

velocity (lengths • s-1) 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

running flying C.L. swimming 0.1 1 10 100 1000 10000 Body Mass (kg)