Aerobic Metabolism and the Steady-State Concept

摘要: This chapter contains an analysis of the steady-state concept, as it is applied during light exercise. In this case, oxygen consumption increases upon exercise onset to attain a steady level, which can be maintained for long period time. The proportional exerted mechanical power. Under these circumstances, there neither accumulation lactate in blood nor changes muscle phosphocreatine concentration: aerobic metabolism sustains entire energy requirement exercising body. Once state has been attained, flow same at all levels along respiratory system. quantitative relations determining across alveoli and are discussed. Special attention given effects ventilation—perfusion inequality diffusion—perfusion interaction equations. cardiovascular responses analysed context equilibrium between systemic delivery return. relationship power discussed, with distinction external internal work cycling. concepts efficiency cost locomotion analysed. Concerning latter, aerodynamic frictional introduced. roles cross-sectional surface area on frontal plane air density To end with, equation linking ventilation, circulation tight manner developed, around notion that homeostasis system values constant tells that, we normoxia, any increase metabolic rate requires ventilation only if pulmonary quotient stays invariant does not change, cardiac output corresponding consumption. At intense exercise, when also occurs hyperventilation superimposes, new would attained \( P_{A}{\text{CO}}_{2} \) lower than 40 mmHg: modified. state, however, never fact, reasons discussed Chap. 3.