Water (circle)Solute (diamond)Aquaporin channelThis idealized animal cell has no cell wall, pumps, or hydrostatic pressure. Water crosses the selectively permeable membrane through aquaporin channels; nonpenetrating solute cannot pass. Equilibrium relative volume = 300 ÷ bath concentration (mOsm/L). At 150 mOsm/L the cell swells to 2.0×; at 300 mOsm/L it stays at 1.0×; at 600 mOsm/L it shrinks to 0.5×. Real animal cells may lyse in very hypotonic solutions. Time units are illustrative. This is not medical advice.