Why haemoglobin in our blood is never 100% saturated?
Answers
The ability of haemoglobin to bind with oxygen is a function of the partial pressure. So if it's a 100% saturated,haemoglobin carries 4 units of oxygen but this can theoretically only happen in the lungs when the partial pressure is a 100mmHg. The thing is,partial pressure in the normal (active) tissues is around 40mmHg which means that haemoglobin gives up around 1/4th of its oxygen due to the lower partial pressure and so at any point of time,haemoglobin can never actually be 100% percent saturated in the active tissues so this mechanism is basically designed to allow haemoglobin to deliver the bound oxygen molecules to the tissues.
Answer
The oxygen-hemoglobin dissociation curve is a plot of percent saturation of hemoglobin as a function of the partial pressure of oxygen (PO2). At a PO2 of 100 mmHg, hemoglobin will be 100% saturated with oxygen, meaning all four heme groups are bound. Each gram of hemoglobin is capable of carrying 1.34 mL of oxygen.
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