What principle describes the movement of water across a membrane from an area of lower solute concentration to higher solute concentration?

The principle that describes the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration is known as osmosis. This process occurs to achieve equilibrium in the concentration of solutes on either side of the membrane. Water, which is a solvent, will move through the membrane to dilute the area with a higher concentration of solutes. This movement continues until the concentrations on both sides are equal or until the osmotic pressure balances the concentrations, preventing further movement of water.

Understanding osmosis is especially important in the context of hemodialysis, as the process is fundamental in regulating fluid balance and solute concentrations in patients undergoing treatment. In dialysis, osmotic gradients are used to remove waste products from the blood and balance electrolytes, demonstrating the critical role osmosis plays in renal function and dialysis therapy.