When red blood cells (RBCs) are placed in solutions of varying concentrations of sodium chloride (NaCl), the effects on the cells can differ significantly based on the concentration of the salt in the solution.
a) RBC in 10% NaCl: When RBCs are placed in a 10% NaCl solution, which is a hypertonic solution, water will move out of the cells into the surrounding fluid to balance the concentration of solutes. This causes the RBCs to shrink (a process known as crenation) as they lose water. The high concentration of NaCl outside the RBCs creates an osmotic gradient that drives water out of the cells.
b) RBC in 0.9% NaCl: A 0.9% NaCl solution is considered isotonic to human RBCs. In this scenario, there is no net movement of water into or out of the cells; the concentrations of solutes inside and outside the RBCs are balanced. As a result, the shape and function of the RBCs remain normal, and they can effectively carry oxygen throughout the body.
c) RBC in 0.1% NaCl: When RBCs are exposed to a 0.1% NaCl solution, which is hypotonic, water moves into the cells from the surrounding fluid. This happens because the concentration of solutes is lower outside the RBCs, creating an osmotic pressure that draws water in. As a consequence, the cells may swell and potentially burst (hemolysis) if too much water enters.
In summary, the effects on RBCs in these three different NaCl concentrations illustrate the principles of osmosis and how various solute concentrations can impact cell shape and integrity.