Exercise alveolar ventilation during

During exercise, the increase in minute ventilation results from increases in tidal volume and breathing frequency. Initially, the increase in tidal volume is greater than the increase in breathing frequency. As discussed earlier in this chapter, increases in tidal volume increase alveolar ventilation more effectively. Subsequently, however, as metabolic acidosis develops, the increase in breathing frequency predominates. 

Cardiovascular Effects. Men exposed in an experimental setting to up to 2,500 mg/m (476 ppm) of vaporized white spirits (83% aliphatic and 17% aromatic components) for 30 minutes had no compound-related changes in electrocardiograms, oxygen uptake, cardiac output, alveolar ventilation, or heart rate measured at rest or during exercise (Astrand et al. 1975). A retrospective cohort study showed no changes in blood pressure in house painters who were exposed to unspecified levels of various solvents for 4-42 years as compared to unexposed workers from other industries (Hane et al. 1977). 

Oxygen makes up 21% of air, with a partial pressure of 21 kPa (158 mm Hg) at sea level. The partial pressure drives the diffusion of oxygen thus, ascent to elevated altitude reduces the uptake and delivery of oxygen to the tissues. air is delivered to the distal airways and alveoli, the PO2 decreases by dilution with carbon dioxide and water vapor and by uptake into the blood. Under ideal conditions, when ventilation and perfusion are well matched the alveolar PO2 will be -14.6 kPa (110 mm Hg). The corresponding alveolar partial pressures of water and CO2 are 6.2 kPa (47 mm Hg) and 5.3 kPa (40 mm Hg), respectively. Under normal conditions, there is complete equilibration ( alveolar gas and capillary blood. In some diseases, the diffusion barrier for gas transport may be increased during exercise, when high cardiac output reduces capillary transit time, full equilibration may not occur, and the alveolar-end-capillary Po gradient may be increased. 

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