Question

explain the relationship between gas partial pressure, diffusion, and respiration through the mammalian respiratory/ circulatory systems.

Answer 1

Partial pressure of a particular gas is the pressure of that gas in a mixture of gases. It is the notational pressure of that particular gas if it had occupied the entire volume of that mixture of gases at the same temperature. This comes to mean that the total pressure of an ideal gas mixture is the sum of the partial pressures of all the gases in the mixture.

Diffusion is a phenomena where molecules move from where they are in higher concentration to the area of lower concentration. It is affected by pressure and temperature.

The partiakl pressure of CO2 and O2 helps in exchange of gases between the inhaled air and blood and then between the blood and the cells of the tissues.

The inhaled air reaches the alveoli. The partial pressure of O2 is more in the air than in the blood in the alveolar capillaries, so the O2 diffuses into the blood. At the same time, the partial pressure of CO2 is more in the alveolar capillaries than in the inhaled air, so CO2 diffuses into the alveoli.

Now, the blood, rich in oxygen is pumped to the body parts. As the blood moves through the tissues, O2 diffuses into the cells because the partial pressure of O2 is higher in the blood than in the tissues. By the same law CO2 diffuses from the tissues into the blood because its partial pressure is lower in the blood than in the tissues.

The CO2 rich blood flows to the heart and then into the lungs and the whole process is repeated again.