Once pathogens have penetrated the non-specific barriers, they are confronted by macrophages and natural killer cells. how do these cells contribute to maintaining homeostasis?

             When a pathogens cross non-specific barriers (skin) they disturb the homeostasis of the body. however inside body they are confronted by different types of white blood cells which are responsible for bringing homeostasis again in the body. these are described below.

Role of macrophages in maintaining homeostasis

Macrophages are white blood cells (phagocytes) constantly patrolling in the body and destroy other cells by engulfing and ingesting them through the process of phagocytosis. These are produced in bone marrow cells as monocytes which have short life of only 10-20 hours. Once monocytes leave the blood they become macrophages. From bone marrow to the blood, macrophages are transported to the area of the body where they are needed. Macrophages engulf the whole body, after digesting particles (bacteria) can extrude the residual particles. Thus, provide protection by trapping and destroying microorganisms entering the tissue. They also secrete different proteins. Some of these proteins trigger the maturation of monocytes into macrophages, thereby increasing their numbers. Another protein interleukin-1 signals the brain to raise the body temperature, producing fever. The higher temperature aids the immune response and inhibit the growth of invading microorganisms.

Role of natural killer cells in maintaining homeostasis

They are another class of white blood cells that don’t directly attack invading microbes. Instead they strike at the body’s own cells that have been invaded by viruses. Virus infected proteins bear viral proteins on their surfaces. Natural killer cells recognize and kill cancerous cells. They secrete proteins into plasma membrane of the infected or cancerous cells. They also secrete enzymes that break up some of the molecules of the target cells, as a result the target cell soon dies.

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