Metabolic scope

Figure 2.5. Metabolic scope for activity (defined as the difference between maximum metabolic rate and the SMR) and the metabolic scope for survival (defined as the difference between the SMR and maximally suppressed metabolic rates). Hummingbird estimates shown for normothermic conditions and for torpor metabolic rates (the latter gives the full biological scope for activity). Suppressed metabolic rates for the aquatic organisms assume temperatures of about 20°C (except for the pumpkinseed, where suppressed metabolism occurs during overwintering hibernation at about 4°C). (Modified from Hochachka (1990.)...

ANAEROBIC METABOLIC SCOPES IN HIGH-PERFORMANCE TUNAS... 

It is important to note that this model predicts the hydrolysis of one ATP for every cross-bridge cycle of every myosin head there is evidence that, in high-speed contractions at least, there may be multiple attachments and detachments per hydrolysis. Thus, our understanding is obviously not complete. Nevertheless, the ATP consumption associated with contraction can be enormous. The metabolic scope (ratio of maximal to resting energy consumption) of skeletal muscle can reach 100 1, and there must necessarily be metabolic specializations to meet this peak demand and to do so quickly. Energy metabolism is discussed in Chapters 13-15 and 18. 

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