Delivery of oxygen to tissues depends on adequate ventilation,
gas exchange and circulatory distribution. At atmospheric
pressure, most of the oxygen is bound to hemoglobin and only a
very small amount is dissolved in the plasma. On exposure to
hyperoxia, hemoglobin becomes completely saturated with
oxygen. While the amount of physically dissolved oxygen also
increases, oxygen has a low solubility in blood and the amount of
dissolved oxygen in blood during normobaric exposures to 100%oxygen can provide only a third of the resting tissue oxygen
requirements