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Blood Cells 101

Posted by Frederick Wasti
Apr 01 2012

Blood Cells

For anyone interested in knowing something about blood cells (something of considerable interest to me, especially over the last year-and-a-half - <g>), here is Fred's "Reader's Digest" treatise on 'em. (Please note that the numbers I've provided below are only approximate values, just to try to keep things simple, and that they can and do vary somewhat from my stated "typical" values, even in a person with "normal" blood.)

[I have tried to keep this as brief as possible, limiting it to ten main points, and the last three are included here primarily for completeness, so, if you're looking for the easiest way out of this blog entry (<g>), please just try to pay attention to the first seven points.] [And there'll be no pop quiz, either...]

1. Blood is made up of a liquid component (plasma, about 55% of the blood volume) and a solid component (blood cells, or corpuscles, about 45% of the blood volume).

2. There are three main types of blood cells - red blood cells (or erythrocytes, filled with hemoglobin, for transporting oxygen and carbon dioxide), white blood cells (or leukocytes, which protect against infections and foreign substances), and platelets (or thrombocytes, which help in blood clotting).

3. Blood cells are generally manufactured in bone marrow tissue, with the rate of production of each usually properly regulated by the body to replace the cells that die (but the rate can increase or decrease as a response to various conditions).

4. Red blood cells normally make up over 99% of the cells in blood, and there normally are about 5,000,000 or so per cubic millimeter. White blood cells are of approximately the same general size range as the far more numerous red cells, but there are normally "only" about 5,000 to 10,000 per cubic millimeter, Platelets are much smaller than either red or white cells, and are intermediate in quantity, there being typically about 300,000 per cubic millimeter.

5. Since leukemia involves certain of the white cells running amok (although leukemia can indeed affect red cells and platelets), let's take a closer look at the five main types of white blood cells or leukocytes (which, by the way, are found not only in the blood, but can also be found in lymph and in body tissues).

6. Neutrophils normally make up about 60% of the white cells, and therefore are easily the most numerous leukocytes. Neutrophils engulf and destroy pathogens (especially bacteria and fungi) and debris.

7. Lymphocytes normally make up about 30% of the white cells, and therefore are generally the second most numerous leukocytes. Lymphocytes, common in both the blood and in lymph tissues (and, unlike all the other blood cells, manufactured not just in bone marrow but also in the lymph tissues), are themselves of several types, but, as an example of one type of lymphocyte, B-lymphocytes are involved with labeling (or "tagging") the surface of foreign invaders and foreign proteins with chemicals called antibodies. (Since lymphocytes are the type of aberrant white cell involved in my type of leukemia, I will certainly have more to say about them later.)

8. Monocytes normally make up about 6% of the white cells. Monocytes engulf and destroy pathogens and debris, especially in body tissues.

9. Eosinophils normally make up about 3% of the white cells. Eosinophils help destroy pathogens (such as larger parasites) and foreign debris that have been marked with antibodies by B-lymphocytes.

10. Basophils normally make up about 1% of the white cells, and therefore are generally the least numerous of the leukocytes. Basophils release histamine into damaged body tissues in order to stimulate inflammation.

I know that the above may be a lot to digest at once, but you can always come back to this and look at it again. Perhaps, though, better than that would be to check other online sources of information - a good source (including excellent pictures) is at http://www.funsci.com/fun3_en/blood/blood.htm

Categories: Leukemia