Principle Chloride Shift

The gist is that the CO2 in blood becomes H2CO3 thanks to carbonic anhydrase, and later to HCO3, and leaves the cell (goes extracellularly), which basically leaves a void in the cell in the form of negative charge or something lol, so chloride goes in its place. This also happens in the Kidney. In respi, opposite happens, where hco3 goes in and chloride goes out, maintaining Hb-O2 dissociation curve.

by Fatima Nabi