The reason why hospitals use saline solutions as drip Instead of water is

Step 1: Analyze the question We're asked why hospitals use saline (salt) solutions for drips rather than plain water.

Step 2: Explain the concept (Osmosis and isotonic solutions) Body cells, especially red blood cells, are surrounded by fluid with a particular concentration of dissolved salts (about 0.9% NaCl). Water moves across cell membranes by osmosis, from a region of higher water potential (dilute) to a region of lower water potential (concentrated).

• If pure water is dripped into the blood, the blood becomes hypotonic (too dilute). Water rushes into the red blood cells, and they swell and may burst (haemolysis).
• If a solution is too concentrated, water leaves the cells and they shrink (crenation).
• Normal (0.9%) saline is isotonic with body fluids. It has the same concentration as blood plasma, so there is no net movement of water in or out of cells.

Step 3: Evaluate the options

• A. Salt is a preservative: True in food, but it is not the reason for use in a drip. Wrong.
• B. To prevent contamination: Sterility prevents contamination, not the salt itself. Wrong.
• C. To maintain the composition of body fluids: Saline is isotonic, so it replaces lost fluid without disturbing the salt and water balance of blood and tissue fluid. Correct.
• D. To increase the number of blood cells: Saline does not produce blood cells. Wrong.

Step 4: Answer

Exam tip: Whenever you see "saline", "drip", or "intravenous", think isotonic = same concentration as body fluids = no osmotic damage to cells. Remember: pure water makes red blood cells burst; strong salt makes them shrink.