Question

How would you best describe the chloride shift in gas exchange?

a. Chloride is taken out of the blood to counterbalance the inflow of carbon dioxide.
b. Chloride rushes into RBCs to counterbalance the outflow of bicarbonate.
c. Chloride binds to bicarbonate, allowing more of it to be carried in the bloodstream.
d. Chloride is removed from hemoglobin when carbon dioxide binds to it.

Answer 1

The chloride shift refers to the exchange of bicarbonate ions within red blood cells for chloride ions from the blood plasma, facilitating carbon dioxide transport and maintaining electrical neutrality in blood.

Step-by-step explanation:

The chloride shift is a critical process in the transport of carbon dioxide in the blood. When carbon dioxide diffuses into red blood cells, it is transformed into carbonic acid (H₂CO₃) by an enzyme called carbonic anhydrase. This carbonic acid then rapidly dissociates into bicarbonate (HCO₃⁻) and hydrogen ions (H+).

As bicarbonate ions accumulate inside red blood cells they are exchanged for chloride ions (Cl⁻) from the blood plasma, thus maintaining electrical neutrality. This ion exchange mechanism is termed the chloride shift. At the lungs bicarbonate re-enters red blood cells in exchange for chloride ions, which helps to reverse the reactions and release carbon dioxide that is then expelled during exhalation.