• Direct
  • Calorimety
• Indirect
  • Radioisotopes
  • ingestion/excretion
  • gas exchange (O₂ consumed)
    • most common
    • only aerobic metabolism

Respirometry

Closed system

• Air does not flow through system
• O₂ use causes fluid in manometer to rise
• O₂ is injected to brng level back to start

• Ratio of CO₂ produced/O₂ consumed
• "R" when measured at gas exchange site (lungs)
• "RQ" when measured at the level of cell
• can be used as a gross indicator of diet

Effects of body size on MR

Isometry

Effects of body size on MR

Allometry

• systematic changes in proportions with increasing size

• Different parts of the body grow/change at different rates
• y=ax^b (b≠1)

• mass-specific MR
  • O₂ uptake/gram
• Whole-animal MR
  • MR per gram decreases with increasign size

1. Glycolysis
2. Kreb/citric acid cycle
3. electron transport chain
4. oxidative phase

• splitting of glucose into pyruvic acid
• ATP yield of 2
• does not involve O₂

• makes electron carriers NADH and FADH₂
• 1 mole of glucose gives:
  • 6 moles of CO₂
  • 8 NADH₂ and 2 FADH₂
  • 2 GTP=2 ATP
• no O₂ involved yet, but Krebs cycle would stop without it
• Why? NADH and FADH need to be regenerated

• mitocondrial matrix electron flow, movement of H⁺
• passes electrons (H) from NADH₂ and FADH₂ along to O₂
• O₂ is the final electron acceptor

• Complexes I, III, and IV can make ATP
• uses energy from proton gradient
• each pair of electrons can lead to 1 ATP in each complex

• Lactic acid accumulation
• acid/base imbalances
• inadequate supplies of glucose
• overheating

• Anaerobic: ATP produces at high rates
• Aerobic: ATP production at low rates
• Lipids: ATP production at 2/3 rate of sugars