Question

in healthy people, it is good practice to use isotonic solutions for injections into veins of the circulatory system because ______
hypertonic solutions cause red blood cells to swell and lyse
isotonic solutions maintain the normal volume and function of red blood cells
hypotonic solutions cause red blood cells to crenate

Explanation:

• Analyze the first option: Hypertonic solutions have a higher solute concentration outside the cell, so water leaves red blood cells, causing them to shrink (crenate), not swell and lyse. So this option is incorrect.
• Analyze the second option: Isotonic solutions have the same solute concentration as red blood cells' cytoplasm. This means there is no net movement of water across the cell membrane, so the normal volume and function of red blood cells are maintained. This matches the reason for using isotonic solutions for injections.
• Analyze the third option: Hypotonic solutions have a lower solute concentration outside the cell, so water enters red blood cells, causing them to swell and lyse, not crenate. So this option is incorrect.

Answer:

B. isotonic solutions maintain the normal volume and function of red blood cells