Red blood cells are placed into a hypertonic saline solution (higher solute concentration than inside the cells). What will occur and why?

• A. Water will move out of the RBCs into the surrounding solution, causing the cells to shrink (crenate) because water follows the higher extracellular solute concentration
• B. Solutes will diffuse into the RBCs through the membrane lowering intracellular osmolarity and thereby drawing additional water into the cells until both compartments have equal solute content
• C. There will be no net water movement because osmotic pressure is always perfectly counterbalanced by hydrostatic pressure in isolated cell suspensions
• D. Water will move into the RBCs causing them to swell and potentially lyse because cells always take on water when placed in any solution that contains electrolytes

Answer: (A)