Byproduct now, these carbon dioxide molecules diffuse across the cell membrane into the extracellular matrix, and they travel into the blood plasma of the nearby capillary. So this is the wall of our capillary. Now, when the CO2 molecules enter the blood plasma then travel into the red blood cell. Now, the majority of the carbon dioxide in the red blood cells is transformed into bicarbonate ions and hydrogen ions. So by increasing the amount of CO2 inside the red blood cell, we also in turn increase the amount of hydrogen ions inside our red blood cells. And because hydrogen ions, the concentration of hydrogen ions, determines the PH of our blood plasma, and what that means is a higher concentration of hydrogen ions means a more acidic environment and so a lower PH.