Every cell is selectively permeable to different molecules. This type of selectively is caused by a semi-permeable membrane, which allows the movement of certain molecules across it. Water exchange can be measured in two ways: RBC osmotic permeability is measured, and diffusional water permeability is measured (Benga and Borza 1995). Diffusion is the movement of high concentration to low concentration. The diffusion of water across a permeable membrane is called osmosis. …
