Explain the transport of O 2 and CO 2 between alveoli and tissue with diagram.

The following diagram shows the transport of O 2 and CO 2 between alveoli and tissue fluid: ∙ In alveoli, pO 2 is 104 mm Hg and pCO 2 is 40 mm Hg. In deoxygenated blood, pO 2 is 40 mm Hg: which is less than the partial pressure of oxygen in alveoli. Due to this it enters the blood in alveoli. ∙ In deoxygenated blood, pCO 2 is 45 mm Hg: which is more than the partial pressure of CO 2 in alveoli. Due to this, carbon dioxide exits from tissue cells and enter the alveoli. ∙ Once blood reaches the tissues, the partial pressure of oxygen in oxygenated blood is 95 mm Hg which is more than partial pressure of oxygen in deoxygenated blood ( 40 mm H g ) . Hence, oxygen from blood enters the tissues. ∙ At the tissue level, the partial pressure of carbon dioxide in deoxygenated blood is more than that in oxygenated blood. Hence, carbon dioxide exits from the tissues.