Blood gas tension Blood gas tension Blood gas tension refers to the partial pressure of gases in blood. There are several significant purposes for measuring gas tension; the most common gas tensions measured are oxygen tension (PO), the carbon dioxide tension (PCO) and carbon monoxide tension (PCO). The subscript "x" in each symbol represents the source of the gas being measured; ""a"" meaning arterial, ""A"" being alveolar, ""v"" being venous, ""c"" being capillary. Blood gas tests (such as arterial blood gas tests) measure these partial pressures. PO – Partial pressure of oxygen at sea level (765 mmHg) in arterial blood is between 75
Hemoglobin dioxide, which causes a conformational change in the protein and facilitates the release of oxygen. Protons bind at various places on the protein, while carbon dioxide binds at the α-amino group. Carbon dioxide binds to hemoglobin and forms carbaminohemoglobin. This decrease in hemoglobin's affinity for oxygen by the binding of carbon dioxide and acid is known as the Bohr effect. The Bohr effect favors the T state rather than the R state. (shifts the O-saturation curve to the "right"). Conversely, when the carbon dioxide levels in the blood decrease (i.e., in the lung capillaries), carbon dioxide and protons are released