VPY-0047
QUESTION
The principle behind chloride-bicarbonate shift is?
OPTIONS
(A) Diffusion
(B) Osmosis
(C) Donnan’s equilibrium
(D) Ex-osmosis
ANSWER
(C) Donnan’s equilibrium
EXPLANATION
Donnan’s equilibrium is the correct option because the chloride-bicarbonate shift in erythrocytes reflects ionic redistribution across the RBC membrane in relation to intracellular charged proteins and changes in bicarbonate/chloride distribution, a phenomenon related to Gibbs-Donnan principles. Diffusion is the physical movement process involved but does not state the physiological principle underlying the equilibrium, osmosis concerns water movement, and ex-osmosis is not the relevant principle.