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Immunity - Coggle Diagram

- - - - form about 60% of all white cells in body
      - travel throughout the body, engulfing pathogens that they find
      - short-lived cells
    - - larger than neutrophils
      - found in organs such as lungs, liver, spleen, lymph nodes, rather than remaining in blood.
      - travel in the blood as monocytes, which develop into macrophages once they leave the blood and settle in organs
      - long-lived cells
      - they cut the pathogens up to display antigens that can be recognised by lymphocytes
    - - chemotaxis > recognition and attachment > endocytosis> pathogen within phagocytic vacuole > fusion of lysosomes and phagocytic vacuole > killing and digestion.
  - - - also called B-cells
      - immature cells divide in the bone marrow by mitosis. They mature in the bone marrow: B cell receptors are formed in the cell surface membranes. Mature cells circulate in the body, concentrating in lymph nodes and the spleen.
      - have the ability to make just one type of antibody molecule, which combines with only one specific antigen. Their shapes are complementary to each other.
      - when a pathogen is detected, clonal selection occurs first. Then, the selected cell divides by mitosis.
        
        plasma cells
        
        secrete antibodies
        
        antibodies
        
        globular proteins, with a quaternary structure
        
        for the group of plasma proteins, called immunoglobulins
        
        four polypeptide chains: 2 light/short and 2 heavy/long. Disulphide bonds hold the chains together. Each molecule has 2 identical variable regions, and a constant region. The amino-acid sequences in the variable regions give specific 3D shapes. The "hinge region" gives flexibility.
        
        memory cells
        
        stay in the body for a very long time, and divide by mitosis in case of another invasion by the same pathogen. They are the basis of immunological memory
    - - Immature T-cells divide by mitosis in the bone marrow. In the thymus, each T-cell matures to form T-cell receptors in the cell surface membrane. The cells then differentiate into T-helper or T-killer/ T-cytotoxic cells
        
        T-helper
        
        Release cytokines (any signalling molecule that influences the growth and differentiation of a cell), which stimulate the appropriate B-cells to divide, develop into plasma cells and secrete anitibodies.
        
        Some release cytokines that stimulate T-killer cells to divide by mitosis and to differentiate by producing vacuoles full of toxins.
        
        Some cytokines stimulate macrophages to carry out phagocytosis more vigorously.
        
        T-killer
        
        Recognise antigens, attach themselves to the surface of infected cells, and secrete toxic substances, killing the body cell along with the pathogen.