Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 29

On your next placement take a few minutes to examine the saline drip bags at the side of your patients’ beds; pay close attention to the chemical composition specified.

What do you notice?

Now that you have an understanding of the composition of isotonic saline, we can explore why these are routinely used in clinical practice.

Human cells are stable in isotonic solutions because the concentrations of dissolved materials (solutes) are equal on both sides of the plasma membrane and so no net movement of water is occurring.

In health, the blood is a near-perfect isotonic medium kept at the same concentration as the cytosol of our cells by a multitude of homeostatic mechanisms. However, in certain diseases human cells can be taken out of their isotonic comfort zone, which can cause damage and in some circumstances become life-threatening.