Perhaps one of the most evocative signs of sudden ill health or damage to the human body is the sight of red streams flowing from a fresh skin cut. Yet this very action, as we shall learn in a moment is just part of the body's many defence mechanisms. In this article, we shall look at key aspects of normal healthy human blood, and with the aid of small images, learn how to identify a few of the more serious diseases of the blood system. Although a serious topic of study, this short article is intended for both students of Biology and general public interest. It is designed to be fairly light and easy to read without the reader requiring previous in-depth knowledge of Biology.
Blood consists mostly of red blood cells with a smaller number of white blood cells.
Several different staining methods are used to make the cells more readily seen under an optical microscope. In Fig.1x you can see a sample of human blood cells. These have been stained to make red blood cells appear as pink or red, and white blood cells appear as dark blue or purple. A quick glance at Fig.1x should demonstrate that all the cells visible are in fact red blood cells. It should be remembered that these colours have been produced artificially.