Immunity
Teacher recommended
?- Created by: Sophie Gibbons
- Created on: 05-01-13 15:53
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- Immunity
- Defence mechanisms
- Specific
- DO distinguish between pathogens.
- Less rapid response but long lasting.
- Involves white blood cells called lymphocytes.
- Cell-mediated involving T lymphocytes.
- Humoral response involving B lymphocytes.
- Non-specific
- Do NOT distinguish between pathogens but responds in the same way.
- Act IMMEDIATLY
- A barrier to pathogens and phagocytosis.
- Lymphocytes
- White blood cells
- Over 10 million different types.
- Proteins on surface have complimentary to shape to proteins on pathogens.
- T lymphocytes involved in cell-mediated immunity, mature in the thymus gland.
- B lymphocytes involved in humoral immunity, mature in the bone marrow.
- How lymphocytes recognise own cells.
- In fetus lymphocytes collide with own cells, those who have receptors that fit those of the body die so the only remaining ones respond to non-self material.
- Specific
- Phagocytosis
- Phagocyte is attracted to pathogen by chemoattractants
- The phagocyte binds to the pathogen
- Phagocyte engulf pathogen forming a vesicle called a phagosome.
- Lysosomes migrate towards the phagosome and fuse with it.
- Lysosomes produce lytic enzymes which break down the pathogen
- Soluble products from the pathogen are absorbed into the phagocyte.
- Lysosomes produce lytic enzymes which break down the pathogen
- Lysosomes migrate towards the phagosome and fuse with it.
- Phagocyte engulf pathogen forming a vesicle called a phagosome.
- The phagocyte binds to the pathogen
- Phagocyte is attracted to pathogen by chemoattractants
- Barriers to entry
- Protective covering - the skin creates continuous layer which is hard to penetrate.
- Epithelia covered in mucus - pathogens stick to mucus and are destoryed.
- Hydrochloric acid in the stomach - enzymes of pathogens are denatured.
- Cell -mediated immunity
- T lymphocytes respond to an organisms own cells which have been invaded by non-self material
- Only respond to antigens that are attached to a body cell.
- Respond to a virus, cancer cell or transplanted material.
- Antigen presenting cells - able to present antigens from other organisms on its surface.
- How lymphocytes distinguish between invader and normal cells.
- Phagocytes present antigens from pathogens on their surface.
- Invaded cells present antigens on their surface.
- Cancer cells present antigens on their surface.
- Pathogen enters body or taken in by phagocytosis, receptors on T helper cells fit the antigens, activates other T cells to divide by mitosis, clone either...
- Develop into memory cells
- Stimulate phagocytes
- Stimulate B cells
- Kill infected cells
- How T cells kill infected cells
- Produce protein which creates holes in cell surface membrane.
- Cell becomes freely permeable to substances and die.
- Antigens
- Any part of an organism which is considered non-self and triggers an immune response.
- Proteins on the surface of pathogens.
- Humoral immunity
- Involves antibodies
- Occurs in blood and tissue fluid.
- Untitled
- Defence mechanisms
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