View mindmap
  • Immunity
    • Non-specific
      • Not specific to individual pathogens
        • Phagocytosis
          • pathogens are destroyed by intracellular digestion involving lysosomal enzymes
          • 1. chemotaxis: Phagocyte moves towards the pathogen, attracted by the chemicals it produces
            • 2. Adherence: Phagocyte membrane invaginates to begin to enclose the pathogen. The phagocyte attaches to the microbe
              • 3.ingestion: The cell membrane of the phagocyte extends projections called pseudopods that engulf the microbe. when pseudopods meet the pathogen the fuse and form a vesicle called phagosome
                • 4. Digestion: the phagosome in the cytoplasm merges with lysosomes forming phagolysosome. The hydrolytic enzymes from lysosomes are released into the phagosome onto the pathogen to hydrolyse it.
                  • 5.Killing: the soluble digested products are absorbed into the cytoplasm of the phagocyte by exocytosis.
        • Rapid as it is carried out by many WBC polymorphs, first to arrive & macrophages develop from monocytes in blood
        • leaky capillaries: plasma seeps into surrounding areas inflammation: swollen with phagocytes, dead pathogens & cell debris(pus). Increased blood flow and hot
    • Specific
      • Distinguishes between individual pathogens & the response is tailored to the pathogen
        • Response is triggered by the body recognising self and non-self cells.
          • Non-self cells aren't recognised by the body hence produce immune response. molecules on cell surface membrane recognise foreign cells known as antigens
            • Antigens: chemicals capable of producing an immune response when comes into contact with complementary lymphocytes
          • Lymphocytes in foetus make contact with each other self cells which are complementary to foetal cells and so are switched off. when baby is born functional lymphocytes aren't complementary to self cells.
        • Slower as there are million functional lymphocytes remaining there are only a few of each type.
        • Lymphocytes- WBC
          • T cells formed from stem cells in the bone marrow and mature in the thymus gland for cell mediated immunity. They respond to antigens and attach to body cells affected by viral infection.
            • cell mediated immunity: t cells are produced as of stimulation by the body's own cells that have been changed due to the presence of non-self material within them called antigen-presenting cells. Each t cells have different roles to battle infection.
              • Antigen-presenting cells cause sensitised t cells to divide to produce a clone.
                • killer t cells: cytotoxic t cells attach to antigen of the infected cell & destroy it by direct enzyme action ie protein perforin punches holes in cell surface membrane & nitric acid destroys it
                • Helper t cells: they stimulate other cells involved in the immune response. B cells divide to produce plasma cells that produce antibodies. They also attach special chemicals ie opsonins and secrete protein interferon that limit viruses from replication.
                • Memory cells: They circulate the body fluid inactively if a subsequent infection occurs the memory cells are already sensitised to rapidly produce a large clone of t lymphocyte cells.  secondary responce
                • suppressor t cells: regulate the immune response of other immune cells by switching off the immune responce after invading microbes when no more antigens are present therefore prevent autoimmune responses.
          • B cells- formed from stem cells in bone marrow where they mature for antibody-mediated(humoral) immunity. They're activated and lead to production of antibodies that respond to antigens in the body fluids. usually bacterial and viral infections.


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Health, illness and disease resources »