In regards to CO2 transport by RBC:

Explanation:

The CO2 dissociation curve is affected by the level of O2 saturation and governed by the Haldane effect which is : Deoxygenation of the blood increases its ability to carry carbon dioxide, and vice versa.

HCO3- diffuses out more easily than the H+ because the cell membrane is relatively impermeable to cations. Thus, to maintain electrical neutrality, Cl- ions move into the cell from the plasma, the so-called chloride shift. Some of the H+ ions liberated are bound to — haemoglobin:

                                                                                    (H+)+ HbO2 -----> H+. Hb + O2

This occurs because reduced Hb is less acid (that is, a better proton acceptor) than the oxygenated form. Thus, the presence of reduced Hb+ in the peripheral blood helps with the loading of CO2 whereas the oxygenation that occurs in the pulmonary capillary assists in the unloading. The fact that
deoxygenation of the Hb increases its ability to carry - is known as the Heldene effect.

These events associated - the uptake of - by 2 increase the osmolar content of the red cell, and, consequently, water enters the cell, thus increasing its volume. When the cells pass through the lung, they shrink a little.

Note that for each CO2 molecule added to a red cell, there is an increase of one osmotically active particle in the cell— either an HCO3– or a Cl– in the red cell. Consequently, the red cells take up water and increase in size. For this reason, plus the fact that a small amount of fluid in the arterial blood returns via the lymphatics rather than the veins, the hematocrit of venous blood is normally 3% greater than that of the arterial blood. In the lungs, the Cl– moves out of the cells and they shrink.