Microgravity

Abstract

Gravity profoundly affects the overall mechanics of the respiratory system. Functional residual capacity, when measured in sustained microgravity, is intermediate to that present in the standing and supine postures in 1G, consistent with early modeling studies. This change occurs almost exclusively through changes in the abdominal compliance and thus in the volume of the abdominal compartment, with the rib cage being relatively unaffected by gravity. Microgravity leaves vital capacity unaltered once the initial translocation of blood into the thorax is corrected by homeostatic mechanisms, but residual volume is reduced, likely through a more uniform distribution of alveolar size permitting deflation to a lower overall lung volume. Expiratory flows are unaffected by microgravity provided they are measured following normalization of the intrathoracic blood volume. During sleep in microgravity, there is an almost complete abolition of obstructive sleep apnea events.

Extraterrestrial CPR and Its Applications in Terrestrial Medicine

“…This expansion can be explained by a decrease in weight of the abdominal wall, which allows the sternum to move in a cranial direction. As well as expanding the ribcage, this induces subsequent relaxation of parasternal intercostal muscles, further increasing the AP distance [33]. The effect of microgravity on chest anatomy was also observed during parabolic flights, whereby a displacement of the sternum in the cranial direction was found in microgravity, accompanied by an increase in diameter of the lower rib cage.…”

Gravitational effect on the cell in bio-fluid suspension

“…The effects of microgravity (10 −6 g; g = 9.81 m/s 2 ) on the human body have been thoroughly studied, with body fluids recognized as a significant source of concern. Prisk [7] states that body fluids collect in the thorax before redistribution and eventual balance. While immune cells can be found as resident cells in tissues, their primary mechanism of movement to their site of action is via hematic or lymphatic streams [8].…”

“…The effects of microgravity (10 -6 g; g = 9.81 m/s 2 ) on the human body have been thoroughly studied, with body fluids recognized as a significant source of concern. Prisk [7] states, body fluids collect in the thorax before redistribution and eventual balance.…”