Patrolling phagocytes, the body’s “eating cells”, often intercept foreign substances that find their way into the body’s lymph, blood, or tissues. The two most common typer of phagocytes, the smaller, short-lived neutrophils, and the larger, tougher macrophages, seek out viruses, bacteria, fungi, protozoa, and other invaders. Doesn’t this make you feel good to know that this kind of wonderful system is working within you right now?
Each day, some 100 billion neutrophils leave the bone marrow and enter the bloodstream Nearly half of them circulate with the blood; the rest, known as the marginal pool, cling to the walls of the blood vessels.
Almost any kind of stress to tissues in the body triggers a rise in the number of blood-borne neutrophils. During severe infections, their number may increase more than fivefold, some originating from the marginal pool, others arising fresh from the bone marrow.
At the appropriate signal from the innate intelligence of the body, the neutrophils leave the bloodstream and migrate into the tissues to pursue invading microorganisms.
AMAZING ISN’T IT?