adaptation biologicaltransport blood cardiovascularphysiologicalphenomena cardiovascularsystem carotidbody chemoreceptorcells chemoreceptors clinicalmedicine congresses diseases effectofspaceflighton erythrocytes evidence-basedmedicine exercise fitness general genetics health internalmedicine medical metabolism oxygen oxygeninthebody physiological physiologicalaspects physiologicaltransport physiology qv312i6131981o qv312o96852000 reducedgravityenvironments respiration respiratoryphysiologicalphenomena spacemedicine sports tissuerespiration weightlessness wf110o982009 wg102