Chapter 8 Outline
Mechanisms of ATP Production and Their Implications
- Aerobic catabolism consists of four major sets of reactions
- BOX 8.1 Reactive Oxygen Species (ROS)
- O2 deficiency poses two biochemical challenges: Impaired ATP synthesis and potential redox imbalance
- Certain tissues possess anaerobic catabolic pathways that synthesize ATP
- Anaerobic glycolysis is the principal anaerobic catabolic pathway of vertebrates
- What happens to catabolic end products?
- The functional roles of ATP-producing mechanisms depend on whether they operate in steady state or nonsteady state
- Phosphagens provide an additional mechanism of ATP production without O2
- Internal O2 stores may be used to make ATP
Comparative Properties of Mechanisms of ATP Production
- Question 1: What is each mechanism’s total possible ATP yield per episode of use?
- Question 2: How rapidly can ATP production be accelerated?
- Question 3: What is each mechanism’s peak rate of ATP production (peak power)?
- Question 4: How rapidly can each mechanism be reinitialized?
- BOX 8.2 Genetic Engineering as a Tool to Test Hypotheses of Muscle Function and Fatigue
- Conclusion: All mechanisms have pros and cons
Two Themes in Exercise Physiology: Fatigue and Muscle Fiber Types
- Fatigue has many, context-dependent causes
- The muscle fibers in the muscles used for locomotion are heterogeneous in functional properties
The Interplay of Aerobic and Anaerobic Catabolism during Exercise
- Metabolic transitions occur at the start and end of vertebrate exercise
- The ATP source for all-out exercise varies in a regular manner with exercise duration
- Related species and individuals within one species are often poised very differently for use of aerobic and anaerobic catabolism
Responses to Impaired O2 Influx from the Environment
- Air-breathing vertebrates during diving: Preserving the brain presents special challenges
- Animals faced with reduced O2 availability in their usual environments may show conformity or regulation of aerobic ATP synthesis
- BOX 8.3 Peak O2 Consumption and Physical Performance at High Altitudes in Mountaineers Breathing Ambient Air
- Water-breathing anaerobes: Some aquatic animals are capable of protracted life in water devoid of O2