[Physiological changes in microgravity].

Microgravity affects the different organ systems to various degrees. In particular, a thoracocephalic fluid shift occurs through suppression of the hydrostatic gradient. Sensory conflict leads to space motion sickness, which is frequent early in the flight, and the musculo-skeletal system is perturbed by the lack of stimuli. The respiratory system seems to be less affected. These changes do not seem to impair health or performance. Humans seem able to adapt to long-term exposure to microgravity, but disorders can occur on return to Earth. In-flight preventive measures need be developed.