Tonicity

Tonicity is a measure of the concentration of solutes in a solution relative to the concentration of solutes in another solution. It is an important concept in biology and medicine, as it determines the movement of water molecules across a cell membrane. When two solutions have the same tonicity, there is no net movement of water. If one solution is hypotonic compared to the other, water molecules tend to move into the hypotonic solution. Conversely, if one solution is hypertonic compared to the other, water molecules move out of the hypotonic solution. Knowing the tonicity of fluids can help health care providers determine the best treatment for patients, such as intravenous fluid administration for dehydration.