Under normal physiological conditions in human being every 100ml of...

Haemoglobin is a red coloured iron containing pigment present in the RBCs. It binds to oxygen in a reversible manner to form oxyhaemoglobin. Each haemoglobin molecule can carry a maximum of
four molecules of oxygen.

The amount of oxygen that binds to the hemoglobin within erythrocytes is primarily related to the oxygen tension which is expressed as the partial pressure of oxygen (pO₂). The relationship between the partial pressure of oxygen (pO₂) and percentage saturation of the hemoglobin with oxygen (O₂) is graphically represented by the oxygen hemoglobin dissociation curve which is sigmoidal under normal conditions.

Every 100 ml of oxygenated blood can deliver around 5 ml of O₂ to the tissues under normal physiological
conditions.