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5 marker first question: phagocytosis stages
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Terms in this set (11)
1. Phagocyte recognises foreign antigens on a pathogen
2. cytoplasm of the phagocyte moves around the pathogen, engulfing it
3. pathogen now contained in a phagocytic vacuole in the cytoplasm of the phagocyte
4. lysosome fuses with the phagocytic vacuole and releases lysozymes that break down the pathogen
5. phagocyte presents the pathogens antigens: it sticks the antigens on its surface to activate other immune system cells
- T cells activate B cells
- white blood cells covered in antibodies that secrete antibodies
- each B cell has a different shaped antibody on its membrane
- when the antibody on the surface of a B cell meets a complementary shapes antigen, it binds to it
- activated by clonal selection
- activated B cells divide into plasma cells
First stage: primary response
- not many B cells that can make the antibody needed to bind to it. The body produces enough of the tight antibody to overcome infection while the infected person shows symptoms of a disease.
- T&B cells produce memory cells that remain in the body and remember the specific antigen for the second time exposed.
- Memory B cells record specific antibodies needed to bind to the antigen.
Second stage: secondary response
-if the same pathogen enters the body again, the immune system will produce a quicker, stronger immune response
- clonal selection speeds up and memory B cells are activated and divide into plasma cells that produce the right antibody for the antigen
- memory T cells are activated and divide into the correct type of T cells to kill the cell carrying the antigen
how a T cell activates a B cellB-cells are activated by the binding of antigen to receptors on its cell surface which causes the cell to divide and proliferate. Some stimulated B-cells become plasma cells, which secrete antibodies. Others become long-lived memory B-cells which can be stimulated at a later time to differentiate into plasma cells. - phagocytes activate T cells - receptor proteins on T cell's surface bind to complementary antigens presented by phagocytes - helper T cells: release chemical signal that activate and stimulate phagocytes and cytotoxic T cells - cytotoxic T cells: kill abnormal and foreign cells