Oxygen Carrying Capacity of Hemoglobin

1 gram of hemoglobin carries how many ml of oxygen?

Correct Answer: 1.34 ml

1 gram of hemoglobin (Hb) carries 1.34 ml of oxygen. This is known as the Hüfner's constant.

Calculation

• Normal Hb concentration in blood = 15 g/dl
• O₂ carried = 15 × 1.34 = ~20 ml O₂ per 100 ml of blood
• This 20 ml/dl is the normal oxygen-carrying capacity of blood.

Forms of Oxygen Transport in Blood

• 98.5% as Oxyhemoglobin (HbO₂)
• 1.5% dissolved in plasma

Hemoglobin Structure

• One Hb molecule = 4 subunits (2α + 2β chains) + 4 heme groups
• Each heme group contains 1 iron (Fe²⁺) atom
• Each Fe²⁺ can carry 1 molecule of O₂
• So 1 Hb molecule carries 4 molecules of O₂