instead of attacking the invaders, they attack the body’s own cells that have become infected by viruses
they also attack potential cancer cells, often before they form tumors
they bind to cells using an antibody “bridge”, then kill it by secreting a chemical (perforin) that makes holes in the cell membrane of the target cell. With enough holes, the cell will die, because water rushing inside the cell will induce osmotic swelling, and an influx of calcium may trigger apoptosis.
Unlike other body systems, Immune System is NOT contained within a single set of organs or vessels
Action depends on structures from lymphatic, cardiovascular, and Integumentary systems
Works primarily through antigen-antibody reaction
Organs of The Immune System The organs of the immune system are stationed throughout the body. They are known as lymphoid organs because they are concerned with the growth, development, and deployment of lymphocytes white blood cells that are key operatives of the immune system.
Plays an active role in defending the body from pathogens
Adenoid Tonsil Lymph nodes Spleen Peyer’s patches (small intestine) Appendix Lymphatic vessels Masses of lymphocytes and macrophages Tissue cells Lymphatic vessel Blood capillary Lymphatic capillary Interstitial fluid Lymph node Interstitial fluid bathing the tissues, along with the white blood cells in it, continually enters lymphatic capillaries. 1 Figure 43.5 Fluid inside the lymphatic capillaries, called lymph, flows through lymphatic vessels throughout the body. 2 Within lymph nodes, microbes and foreign particles present in the circulating lymph encounter macro- phages, dendritic cells, and lymphocytes, which carry out various defensive actions. 3 Lymphatic vessels return lymph to the blood via two large ducts that drain into veins near the shoulders. 4