The cells have no capability to store oxygen, yet all cells require it as an essential metabolic fuel. Without constant delivery, tissue hypoxia and anaerobic metabolism ensue. Tissue hypoxia is defined as inadequate critical oxygen tension to meet the needs of the cell. It is not synonymous with, but closely related to, arterial hypoxaemia which is decreased Po, in the arterial blood.
Blood requires an oxygen carrier because of the limited solubility of oxygen. At a Po, of 100 mmHg, one litre of plasma will contain only about 3.03 mL of dissolved oxygen (0.136 mmoVL). At rest the cardiac output is -5 Limin giving a delivery of dissolved oxygen to the tissues of15 mL/min a grossly inadequate amount considering that tissue require- ments for oxygen are -250 mL/min at rest and -4L/min during exercise. This problem is overcome by haemoglobin which enables the blood to carry up to 200 mL of oxygen per litre.
Blood requires an oxygen carrier because of the limited solubility of oxygen. At a Po, of 100 mmHg, one litre of plasma will contain only about 3.03 mL of dissolved oxygen (0.136 mmoVL). At rest the cardiac output is -5 Limin giving a delivery of dissolved oxygen to the tissues of
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