Final answer:
An isotonic solution has the same concentration of nonpenetrating solutes as normal body cells, ensuring no net water movement across the cell membrane and keeping cells' shape and function normal.
Step-by-step explanation:
A solution that has the same concentration of nonpenetrating solutes as normal body cells is known as an isotonic solution. In an isotonic solution, the solute concentration is equal both inside the cell and in the extracellular fluid, which results in no net movement of water across the cell membrane. Therefore, the cells maintain their normal shape and function because the osmotic pressure inside the cells is balanced with the osmotic pressure outside the cells.
Isotonic solutions are crucial for maintaining cellular integrity and function, especially when administering intravenous fluids in a medical setting to ensure they have the same osmotic pressure as the body fluids.