ZIZ 034 Immunabwehr / immune defense

siehe Ton when the skin as the barrier is injured bacteria can enter. Macrophages migrate from the blood vessels into the tissue. and start their job as big eater. Beside unripe dendritic cells which are existing in the tissue are also eating some of the invaders and go to the lymphnodes to do their job: they fragment the bacteria and bind harmless parts of it to the MHC. These complexes, the so called antigens are presented on the cell surface. All white blood cells are flushed in periodic intervals through the lymphnodes. The T cells are binding accidential. If the MHC with the antigen fits to the T cells receptor like lock and key the T cell is activated and starts to divide. Meanwhile the macrophages are sending second messengers that helps the Th cellsand B cells to find the damage spot.. The b cells can ingest invaders and present the antigen. the activated Th cells are attracted and bind to the complexes. That stimulates the b-cell to divide and produce antibodys which bind to the bacteria and initiate their ellimination

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