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How do low-salt and high-salt solutions affect red blood cells?
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blood
Blood sediment in test tubes, showing plasma (clear fluid), red blood cells (red), and the release of hemoglobin into the surrounding plasma (pink).
Red blood cells are highly sensitive to the osmotic concentration of their surrounding environment due to the permeability of their membranes to water.2
- Low-salt (hypotonic) solutions: When red blood cells are placed in a dilute solution, they take in water through osmosis. This causes the cells to increase in volume and become more spherical. If the influx of water is sufficient, the membrane may stretch and rupture, a process known as hemolysis, which releases hemoglobin into the surrounding medium.12
- High-salt (concentrated) solutions: In a concentrated salt solution, the osmotic gradient causes the red blood cells to lose water. As a result, the cells shrink, a process that leads to the formation of notched or scalloped margins known as crenation.23
Maintaining the proper balance of solutes is essential for the structural integrity of these cells, as excessive stretching or shrinking can lead to cell damage or destruction.2