The lung is exquisitely sensitive to gravity, which induces gradients in ventilation, blood flow, and gas exchange. Studies of lungs in microgravity provide a means of elucidating the effects of gravity. They suggest a mechanism by which gravity serves to match ventilation to perfusion, making for a more efficient lung than anticipated. Despite predictions, lungs do not become edematous, and there is no disruption to, gas exchange in microgravity. Sleep disturbances in microgravity are not a result of respiratory-related events; obstructive sleep apnea is caused principally by the gravitational effects on the upper airways. In microgravity, lungs may be at greater risk to the effects of inhaled aerosols.
Division of Physiology, Department of Medicine, University of California—San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0931, USA
This work was supported in part by NASA contract NAS9-98124 and NASA cooperative agreement NCC9-168.
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