[Phenomenology and mechanisms of changes in the basic functions of the human body in weightlessness].

In the course of the space era the duration of manned flights increased from 108 minutes to 326 days. During the flights a large number of biomedical investigations were carried out to study the phenomenology and mechanisms of space flight effects on the human body. It was demonstrated that exposure to microgravity produced most significant changes. Short-term effects include space adaptation syndrome changes associated with fluid shifts and changes in movement coordination. Long-term effects involve various changes in the musculoskeletal system, cardiovascular system, metabolism and its regulation, endocrine system, blood and immunity system. This paper describes symptom-complexes that are consistently observed in space flight, discusses mechanisms of changes and adaptation of vital physiological systems, and outlines main periods of changes during and after flight.