Why do hospitals inject saline into your bloodstream instead of just water?

Question

Why do hospitals inject saline into your bloodstream instead of just water?

In: 110

Answer 1

Because your cells have stuff in them. Ions, molecules, hormones, hemoglobin, all the things they use to do work and reproduce. Water travels down a concentration gradient until the concentration equalises. Put a red blood cell into water and the water will travel into the cell until it bursts and the concentration of hemoglobin equalises. We don’t want to do this inside your body, hence using isotonic solutions.

We do the same when we take your blood out of your body, I always wash blood cells, or dilute blood using 0.8% saline.