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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 an organism requires and uses for these activities?. Burn 1 mol (180g) of glucose in a calorimeter*:

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Whole-Animal Metabolism

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  1. 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?

  2. 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 Look at heat production: www.umr.edu/-gbert/animation.html

  3. 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

  4. 1 mol glucose + 6 mol O2 + 36 mol ADP + 36 mol Pi 6 mol CO2 + 42 mol H2O + 36 mol ATP + 423 kcal Again, assuming an organism is respiring aerobically, what alternative measures might we use to approximate the metabolic rate? Hint: Answer? Oxygen consumption Carbon dioxide expiration

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

  6. 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

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

  8. 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.

  9. In humans, VO2 can increase 15-20 X during exercise • In insects, VO2 can increase 50-200 X during flight: • Activity vs. VO2 Locomotion is expensive:

  10. SMR • VO2’ activity (e.g. swimming speed)

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

  12. • VO2 liters O2 • kg-1 • h-1 C.L. = = = liters O2 • kg-1 • km-1 velocity km • h-1 Salmon C.L. 0 1 2 3 4 velocity (lengths • s-1) Cost of Locomotion

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

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