What is the difference between isotonic and hypotonic solutions?

Isotonic solutions are characterized by having the same osmolarity as body fluids, which means they do not cause water to move into or out of cells. This equilibrium is crucial for maintaining cell shape and function, as it ensures that there is no net movement of water that could lead to cell swelling or shrinking. On the other hand, hypotonic solutions have a lower osmolarity compared to body fluids, which can lead to water moving into the cells. This influx of water can cause the cells to swell and potentially burst, a process known as lysis.

This understanding of osmolarity is essential in clinical settings, particularly when administering intravenous fluids. Isotonic solutions are commonly used to replace fluids since they maintain balance, while hypotonic solutions may be used with caution, often in specific situations where cellular hydration is needed. It's important for healthcare providers to recognize these differences to prevent complications related to cellular fluid shifts.