Question

Explain what partial pressure is. List the partial pressures of O2 and CO2 in alveolar air and explain what determines their values (discuss each gas separately). List the partial pressures of O2 and CO2 in systemic arterial blood and explain what determines their values. List the partial pressures of O2 and CO2 in systemic venous blood and explain what determines their values.

Answer 1

Partial pressure is definited as a pressure that the specific gas would have produced if it was alone instead of a mixture of gases .

At alveoli

In the alveoli partial pressure of oxygen is 104 mmHg . This value is determined by the oxygen intake by tissue . The atmospheric pressure is 159. So a pressure gradient will develop and O2 will move in

Co2 in alveoli

Partial pressure of co2 in alveoli is 40. . This is determined by the amount of co2 Thein atmospher . partial pressure of co2 in blood is 46 so this pressure gradient will force the movements of co2 to alveoli

O2 in systemic arterial blood

Partial pressure of O2 is 95 mmHg in systemic artery and is determined by the diffusion pressure gradient between alveoli and atmosphere oxygen . The tissue po2 is 40mmhg so O2 moves in

Pco2 of arterial blood

Pco2 of arterial blood is 40 mmHg . This is determined by the pressure Gradient and exchange of co2 between alveoli and blood . The pco2 in tissue is 46 mmHg which cause the movement of co2 outside to blood vessels

Partial pressure if venous blood

Partial pressure of O2 is 40 mmHg in venules . This is determined by the consumption of O2 by the tissue . This low po2 is for the creation of pressure gradient in alveoli to create O2 movement into blood from alveoli

Partial pressure of co2 is 46 mmHg . This will be determined by the production of co2 by the cells . It helps in creation of pressure gradient such that co2 moves into alveoli