Transportation of oxygen:

1. When oxygen is inhaled it reaches the alveoli (tiny balloon like structures which are in close proximity of various thin capillaries).

2. Now, the partial pressure of oxygen is more in the alveoli than the capillaries .

3. This causes the diffusion of oxygen into the capillaries

4. After which oxygen combines with Haemoglobin to form oxyhaemoglobin

5. This oxygenated blood reaches the organs which have low partial pressure than the capillaries.

6. In these organs the bond between oxygen and haemoglobin becomes unstable and breaks releasing oxygen into the organs.

Transportation of Carbon Dioxide:

Carbon dioxide is transported by three different methods which are :

3. Blood carries released carbon dioxide from various organs to the alveoli via capillaries which have lower intra pulmonary pressure than the organs.

4. Now, carbon dioxide is then diffused into the alveoli from the capillaries due to lower intra pulmonary pressure in the alveoli than the capillaries

5. In Red blood cells carbon dioxide combines with water and forms carbonic acid. It is an unstable form and gets disassociated into hydrogen and bicarbonate ion.

6. Carbon dioxide is also transported through plasma in the form of bicarbonate ions.