Final answer:
If the intracellular ion concentration is greater than the extracellular concentration, fluid will move into the cell due to osmosis. The sodium-potassium pump contributes to maintaining ion balance, but in isotonic solutions, no net water movement will occur. In hypotonic solutions, water can enter the cell, potentially causing it to swell.
Step-by-step explanation:
If the intracellular concentration of ions is greater than the extracellular concentration, fluid will move into the cell to balance the concentrations. This movement is due to osmosis, where water moves from an area of lower solute concentration to an area of higher solute concentration. The sodium-potassium pump plays a key role in maintaining ion gradients by pumping sodium out and potassium into the cell, utilizing ATP as energy. However, in an isotonic solution, no net water movement will occur since the extracellular fluid has the same osmolarity as the cell.
In a hypotonic solution, where the intracellular osmolarity is higher than that of the extracellular fluid, water will enter the cell. This can lead to swelling or even bursting of the cell if excessive. The balancing of ion concentrations is critical for the proper function of cells and to maintain the membrane potential necessary for cellular processes.