. "\"The series of events in which a stimulus indicating lowered oxygen tension is received by a cell and converted into a molecular signal. Hypoxia, defined as a decline in O2 levels below normoxic levels of 20.8 - 20.95%, results in metabolic adaptation at both the cellular and organismal level.\" [GOC:BHF, GOC:mah]" . . "detection of hypoxia" . "detection of reduced oxygen levels" . . .