Transport of Gases - Oxygen Transport

Description:

RBCs contain a red coloured pigment called haemoglobin. Oxygen can bind with haemoglobin in a reversible manner. Oxygen bound haemoglobin is called oxyhaemoglobin. A molecule of haemoglobin can bind to four molecules of oxygen.

Factors affecting formation of oxyhaemoglobin

• Partial pressure of O₂.
• Partial pressure of CO₂.
• Hydrogen ion concentration.
• Temperature.

Oxygen Dissociation Curve

• Percentage saturation of haemoglobin with O₂ is plotted against pO₂.
• A sigmoid curve is obtained.
• Used to study the effect of factors like pCO₂, hydrogen ion concentration etc.

• In alveoli, pO₂ is high, pCO₂ is low, lower H⁺ and low temperature are favourable for the formation of oxyhaemoglobin.

• In tissues, pO₂ is low, high pCO₂, high H⁺ and higher temperature make it a favourable environment for the dissociation of oxygen from oxyhaemoglobin.

• Oxygen gets bound to haemoglobin in the lung surface and gets dissociated at the tissues.

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