Matching O₂ Delivery to O₂ Demand in Muscle: I. Adaptive Variation

Abstract

This paper and the following one by C.R. Taylor et al. report an attempt to look at the conditions for O₂ delivery from the atmosphere to the mitochondria in muscle cells in an integrated approach, and this in a double sense: 1) we look at all steps in the transfer pathway that leads from the lung through the circulation and the microvasculature to the O₂ consumption site in the mitochondria; 2) we consider both the structural design and the functional performance at each step. In addition, we are interested mostly in what is happening at very high levels of O₂ consumption, first because under these conditions 90-95% of $\rm\dot{v}$ O₂ occurs in the muscles, so we know the target for O₂ entering the system at the lung, and second because the limit to VO₂ is of particular interest in this context. We would like to know at what level in the respiratory system is this limit set and for what reasons, physiological or structural.