Final answer:
The term for when the concentration of solutes is equal on both sides of the cell membrane is 'isotonic,' resulting in no net water movement in or out of the cell.
Step-by-step explanation:
When the concentration of solutes in a solution is equal on both sides of the cell membrane, it is called an isotonic situation. In an isotonic solution, the extracellular fluid has the same osmolarity as the fluid inside the cell, leading to no net movement of water into or out of the cell. This balance is crucial as it ensures that cells maintain their normal shape and function, since the osmotic pressure on either side of the semipermeable cell membrane is equalized.
The concept of an isotonic environment also applies to the body's fluids, including blood plasma, cytosol, and interstitial fluid. These fluids must maintain isotonic conditions with cells to prevent cell shrinkage or swelling which could result in cellular damage or dysfunction.