What happens to red blood cells in a hypertonic solution?

In a hypertonic solution, the concentration of solutes outside of the red blood cells is higher than that inside the cells. This creates an osmotic gradient where water moves out of the cells in an attempt to balance the solute concentrations. As water leaves the red blood cells, they lose volume and become smaller, a process known as crenation. This shrinking occurs because the cells are essentially dehydrating due to the osmotic pressure exerted by the surrounding hypertonic solution.

Understanding the behavior of cells in different tonicities is crucial in medical settings, especially in the administration of IV fluids and understanding conditions that lead to cell damage due to osmotic imbalances.