Where does gas exchange in the respiratory system occur?

Gas exchanges between Alveolar Spaces and Capillaries.

The function of the is to exchange two gases: ##O^2## and ##CO^2##. The exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. This can be explained as follows-

Inhalation

1. The##O^2## gas which is inhaled by us reaches to the lungs from the Wind/Respiratory pipe.

2. In the lungs it reaches the Alveolar Structures through the bronchioles. The layers of cells lining the alveoli and the surrounding capillaries are each only one cell thick and are in very close contact with each other.

3. So ##O^2## gas passes quickly through this Air-Blood Barrier .

4. It reaches the to the blood in the capillaries. And from there It is transferred to the Heart through the Pulmonary Veins.

5. It enters Heart through the left side of the heart, which pumps the blood to the rest of the body.

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Exaltation

6. Now, Deoxygenated Blood or ##CO^2## rich Blood enters the Heart through from the right side of the Heart.

7. Then the blood is pumped through the pulmonary artery to the lungs.

8. Here again the ##CO^2## Rich blood passes through the Air-Blood Barrier and ##CO^2## gas reaches lungs from where it is released and ##O^2## gas is again Inhaled.