What do hypotonic solutions do to body fluids?

Hypotonic solutions have a lower concentration of solutes compared to the fluid inside the body's cells. When a hypotonic solution is introduced into the body, it causes water to move from the solution into the cells. This movement occurs through the process of osmosis, where water flows from an area of lower solute concentration (the hypotonic solution) to an area of higher solute concentration (inside the cells). As a result, this influx of water shifts body fluids out of the blood vessels and into the cells, leading to cellular swelling.

The other choices are not aligned with the properties of hypotonic solutions. For example, hypotonic solutions do not retain fluids within blood vessels; instead, they promote fluid movement into cells. They also do not increase blood pressure — in fact, they may lead to a decrease in blood pressure if there’s significant fluid shift from the vascular space. Lastly, while hypotonic solutions can potentially cause cells to swell, they do not rapidly dehydrate cells; rather, they hydrate them by increasing intracellular fluid. This understanding is crucial for managing fluid and electrolyte balance in various medical situations.