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31.6 Diseases that Weaken the Immune System KEY CONCEPT When the immune system is weakened, the body cannot fight off disease.

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Presentation on theme: "31.6 Diseases that Weaken the Immune System KEY CONCEPT When the immune system is weakened, the body cannot fight off disease."— Presentation transcript:

1 31.6 Diseases that Weaken the Immune System KEY CONCEPT When the immune system is weakened, the body cannot fight off disease.

2 31.6 Diseases that Weaken the Immune System Leukemia is characterized by abnormal white blood cells. –characterized by immature B-cells –causes weakened immune system Leukemia is cancer of the bone marrow.

3 31.6 Diseases that Weaken the Immune System Leukemia leads to opportunistic infections. –occur because white blood cells cannot fight infections –if immune system were healthy, it would fight these infections

4 31.6 Diseases that Weaken the Immune System HIV targets the immune system. The human immunodeficiency virus (HIV) is a RNA retrovirus. –attacks and weakens the immune system –is transmitted by mixing infected blood with a bodily fluid

5 31.6 Diseases that Weaken the Immune System HIV infection leads to AIDS. HIV T cell dead T cell antibody activated B cell –HIV reproduces in and destroys T cells. –The body cannot replace T cells fast enough. –T cells cannot help in immune responses.

6 31.6 Diseases that Weaken the Immune System AIDS is acquired immune deficiency syndrome. –several opportunistic infections = infections succeed because T cells are gone—they take opportunity to survive –very low amount of T cells (less than 200 T Cells)


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