1. Water Movement: Due to the concentration gradient, water molecules move into the RBCs through osmosis. The hypotonic environment causes water to enter the cells in an attempt to equalize the solute concentrations on both sides of the cell membrane.
2. Swelling and Expansion: As water enters the RBCs, they swell and expand in size. The cell membrane stretches and becomes thinner due to the influx of water.
3. Loss of Shape: The biconcave shape of healthy RBCs is lost, and the cells start to become spherical. This change in shape is a result of the increased internal pressure caused by the water influx.
4. Hemolysis: If the hypotonic solution is sufficiently dilute or the exposure time is long enough, the RBCs can swell and burst, a process called hemolysis. The cell membrane can no longer withstand the internal pressure, and it ruptures, releasing the cell's contents into the surrounding solution.
5. Release of Hemoglobin: As a consequence of hemolysis, hemoglobin, the oxygen-carrying protein in RBCs, is released into the extracellular fluid. This can have implications for oxygen transport and may lead to anemia if a significant number of RBCs are lysed.
The extent of swelling and hemolysis depends on the tonicity of the hypotonic solution and the duration of exposure. In physiological settings, RBCs encounter variations in osmotic conditions as they navigate through different body compartments, but they maintain their structural integrity due to various protective mechanisms and regulatory systems.
