Partial pressure of O2

What is partial pressure of oxygen? (pO2)

Measure of oxygen concentration

How does partial pressure work?

The greater the concentration of dissolved oxygen in cells, the higher the partial pressure

What is partial pressure of carbon dioxide? (pCO2)

The measure of the concentration of CO2 in a cell

How does haemoglobin’s affinity for oxygen vary, depending on the partial pressure of oxygen?

• Oxygen loads onto haemoglobin to form oxyhaemoglobin when there is a high pO2

• Oxyhaemoglobin unload its oxygen when there is a low pO2

How does the transport of oxygen work in terms of pO2?

• O2 enters blood capillaries at the alveoli in the lungs

• It has a high pO2 so oxygen loads onto haemoglobin to form oxyhaemoglobin

• When cells respire, they use up O2 so it lowers pO2.

• Red blood cells unload O2 at respiring cells