Question

How are oxygen and carbon dioxide transported in the blood?

Answer 1

Once the oxygen diffuses into the alveoli, it reaches the circulation and is transferred to the tissues where it is unloaded. To be expelled from the body, carbon dioxide diffuses from the blood and through the alveoli. The primary function of the lungs includes the transfer into the blood of oxygen from the inhaled air and the transfer into the exhaled air of carbon dioxide from the blood.

Complete answer:
Oxygen transport in the blood takes place via RBCs. Oxygen is released by the body through inhalation, and oxygen diffuses from the lungs into the circulation. As soon as it enters the blood, it binds to the haemoglobin in the RBC. 3 percent of oxygen is dissolved in the blood where 97 percent of transported oxygen is bound to haemoglobin. In the tissues, this oxygen then diffuses.

As a result of transpiration within the cells of the body, carbon dioxide is released. The carbon dioxide diffuses from the cell into the blood where it is transferred as:
1. Bound to haemoglobin in the form of carbaminohemoglobin.
2. Dissolved in plasma
3. in the form of bicarbonate ions

It is maximally transported as bicarbonate ions by carbon dioxide which is returned to the lungs with the aid of blood where the diffusion of these gases takes place due to their partial pressures and is released back into the environment.

Note: A property of haemoglobin first described by John Scott Haldane is the Haldane effect. Blood oxygenation of the lungs substitutes haemoglobin with carbon dioxide, which improves the removal of carbon dioxide. The Haldane effect is this property. Oxygenated blood, however, has a diminished affinity for carbon dioxide.