Acquiring immunity Flashcards
Lymphatic system
It acts as a transport network and works closely with the circulatory systems, monitoring the body for signs of infection. The lymphatic system has several functions:
- production and maturation of immune cells
- allowing for the process of antigen recognition by T and B lymphocytes.
Lymph
is the fluid in the lymphatic system that gets squeezed out of blood vessels.
Primary lymphoid organs
Bone marrow - site of maturation for B cells
Thymus - site of maturation for T cells
Secondary lymphoid organs
sites where mature B cells and T cells are activated by meeting their complementary antigens and developing into effector cells.
- Spleen - contains T and B cells
- Lymph nodes - site where antigen recognition occurs (adaptive immune response) where APC display their antigens to their specific T and B lymphocyte
Adaptive immunity
- Specificity - Adaptive immune cells have unique receptors that recognise specific antigens.
- Immunological memory - ability of adaptive immune cells to remember antigens after primary exposure. It enables a more rapid and stronger response in the case of future infections from the same pathogen
Humoral adaptive immunity (extracellular)
- Extracellular pathogens are phagocytosed by APC, processing and present foreign antigens on their MHC 2 class marker
- APC interact with selected T helper cells (when bind = clonal selection)
- T helper cells produce cytokines to stimulate selected B cells (when bind = clonal selection)
- B cells undergo clonal expansion followed by differentiation into plasma and B memory cells which produce antibodies
- The antibodies travel to the pathogen and bind to the antigen
- B memory cells contribute to immunological memory by rapidly dividing and forming new antibody-producing plasma cells when they encounter an antigen that matches their receptor
Cell mediated adaptive immunity (intracellular)
- Intracellular pathogens or damaged cells are phagocytosed by APC and present foreign antigens on their MHC 2 class marker
- APC interact with selected T helper cells(when bind = clonal selection)
- T helper cells produce cytokines to stimulate selected T cells
- T cells undergo clonal expansion followed by differentiation into T memory cells and cytotoxic T cells
- Cytotoxic T cells travel from the lymph nodes to the entire body. They release chemicals such as perforin to induce apoptosis in the cell
- T memory cells proliferate rapidly into T memory and cytotoxic T cells
Antibody
- Specific protein produced by lymphocytes in response to a particular antigen with which it binds to
- All antibodies have same basic structure of four polypeptide chains (2 heavy, 2 light)
Light chains have constant region (same for all antibodies) and
Variable region (where antibody binds to its specific antigen)
Antibody PIANO
Precipitation, inflammation, aggulation, neutralisation of pathogen, neutralisation of toxins, opsonization
Precipitation
Antibodies bind to soluble antigens, making them insoluble.
Inflammation
Antibodies can trigger the release of histamine, causing inflammation.
Agglutination
Antibodies bind to the surface antigens on pathogens to form antigen–antibody complexes. By doing this to various pathogens, it can cause them to clump together and be more visible to the immune system.
Neutralisation of pathogens
Antibodies bind to surface antigens on pathogens and form a coating that neutralises pathogens by blocking their receptors so the pathogens cannot attach to healthy body cells and infect them.
Neutralisation of toxins
Antibodies bind to bacterial toxins, animal toxins and venoms. The antibodies bind to and neutralise the harmful effects of the toxin or venom.
Opsonisation
Antibodies bind to the surface antigens on pathogens to form antigen–antibody complexes and tag the pathogen for destruction.
