Systems Investigation on Self—Adaptation Characteristics of Human Body System During Head Down Tilt Bed Rest

Eight to twenty—three day bed—rest tests with head down tilt (HDT) 0—6°in 40 healthy young men (in 5 groups) were carried out. Sixteen to twenty—eight physiological and biochemical parameters were observed and analyzed before、during and after bed rest. Macro integral system analysis was performed. For every subject, all of the multiple original observed parameters were substituted with 2—4 comprehensive parameters which provided more than 70% information. The locations and traces of physiological functional state points were found to reflect whole body system functional state in the 2—4 dimensional system phasic space composed by these comprehensive parameters. The system struc tural characteristics of self—organization and self—adaptation of various individual body systems during bed—rest tests could be understood from the main physiological meanings of comprehensive parameters. There were individual differences in the traces (directions, distances, undulations and fluctuations) of physiological functional state points during bed—rest tests. The characteristics of regulations and the degree of recovery would be reflected by them.