Hemoglobin is a protein in your red blood cells that carries oxygen to your body's organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs.
Hemoglobin has three functions, Oxygen Transport, Carbon Dioxide transport, and the maintenance of blood pH.
The function of hemoglobin is to readily bind oxygen molecules in the lung, which requires high oxygen affinity; to transport oxygen, and to efficiently unload oxygen to the tissues,
which requires low oxygen affinity. The affinity of hemoglobin for oxygen relates to the partial pressure of oxygen (PO2), often defined in terms of the amount
of oxygen needed to saturate 50% of hemoglobin, called the
P50 value.
A second crucial function of hemoglobin is the transport of carbon dioxide. In venous blood, the carbon dioxide diffuses into the red blood cells and combines with water to form carbonic acid (H2CO3). This reaction is facilitated by the RBC enzyme carbonic anhydrase. Carbonic acid then dissociates to release H1 and bicarbonate.
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