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WEEK 7:
How the body responds to infection:
| Question | Answer |
|---|---|
| 3 layers of defence | barriers, innate immune system, adaptive immune system |
| what kind of barriers are there | mechanical (skin), chemical and biological (microbes) |
| what do the innate and adaptive immune systems use to sense threats | cell surface, soluble receptors |
| innate system receptors | limited pattern recognition receptors (PRR) |
| adaptive system receptors | many different somatically generated receptors |
| routes of infection (4) | aerosol, direct mucosal contact, faeco-oral route, blood to blood |
| faeco-oral route | trace of feces in food due to contamination eg no wash hands |
| what does the respiratory tract epithelium have | mucous secreting cells + cilia |
| eye innate defense | nerve reflex to close eyelids + lacrimal gland secretes tears to wash away pathogens and contain lysozyme to break down bacterial cell walls |
| what is used to prevent infection from ingested source | HCL, enzymes, secretions from the small intestine, and a layer of protective mucus |
| what does the layer of protective mucus make in the gut | immunoglobins (IgA) which disable many bacteria |
| how can the balance of gut biome be ruined | antibiotics kills one type of bacteria so other can survive (natural selection) |
| pseudomembranous colitis | a bacteria that proliferates when antibiotics kill another species of bacteria, caused by clostridium difficile |
| general approaches to prevent death + disease (3) | isolate organism, disrupt organism, consume organism |
| example of isolating an organism | eg granuloma formation in tuberculosis |
| how can you disrupt an organism | physically damage membrane/ activate apoptosis in cancer cells eg natural killer cells in virally infected/ cancerous cells |
| how can you consume organisms | phagocytosis of bacteria via macrophages |
| give 2 examples of innate and adaptive immunity mediators | cytokines (eg IL-1) + complement proteins and complement regulatory proteins (eg decay accelerating factor) |
| cytokines | small polypeptides released by cell in order to change function of same or another cell |
| main immune cytokines | interferons (IFNs) and interleukins (IL) |
| types of IFNs | alpha, beta, gamma |
| how many types of INL are there | 35 |
| chemokines | activate immune cells and stimulate chemotaxis (attract cells along chemical concentration gradient from the blood into tissues and tissues into lymphatics) |
| what does IL-6 act on | liver |
| what does IL-8 and alpha chemokine act on | vascular endothelium |
| what does IL-6 do | production of acute phase proteins (eg c-reactive protein) and elevate temperature (fever) |
| what does IL-8 and alpha chemokine do | activate vascular endothelium and attract/activate neutrophils |
| complement | assortment of macromolecules circulating the blood which precipitates in specific sequence to form MAC on pathogen cell membranes |
| MAC | membrane attack complex |
| how does complement act as a opsonin | C3b receptors on the surface of neutrophils and macrophages induce phagocytosis (act as tags) |
| how does complement act as a chemotaxant | attracts immune cells to infection site |
| main functions of complement (4) | promote inflammation, recruit cells via chemotaxis, kill targeted cells, solubilise and remove antigen-antibody complexes |
| how do complement promote inflammation | through actions of anaphylatoxins C3a, C4a and C5a |
| failure to remove immune complexes (antibody-antigen complexes) can lead to what | immunopathology in the joints, kidney and eye |
| diapedesis | migration between endothelial cells |
| describe the transport of leukocytes (WBCs) | leave capillaries/venules via diapedesis and enter connective tissue compartment |
| types of leukocytes | granulocytes and agranulocytes |
| granulocytes | leukocytes with specific granules |
| agranulocytes | leukocytes that do not have specific granules |
| types of agranulocytes | lymphocytes and monocytes |
| types of granulocytes | neutrophils, eosinophils, basophils |
| percentage of neutrophils in WBC count | 60-70% |
| neutrophil nucleus | 2-3 lobules |
| neutrophil cell membrane | Fc receptor, complement receptor for C3b, L-selectin and integrins |
| what are the L-selectin and integrins used for in neutrophils | adhesion to endothelial lining |
| how do neutrophils kill pathogens | release enzymes from specific granules, phagocytosis using Fc and C3b receptors |
| percentage of lymphocytes in WBC count | 20-25% |
| lymphocyte nucleus | acentric nucleus occupying most of cytoplasm |
| types of lymphocytes | B cells, T cells and null cells |
| B cells | 15%- humorally mediated immune response, become immunologically competent in bone marrow and when antigenically stimulated they become antibody producing plasma cells |
| T cells | 80%- cell mediated immune response, become immunologically competent in thymic cortex (thymus) |
| null cells | 5%- stem cells and Nk cells |
| monocyte nucleus | kidney shaped |
| transport of monocytes | released from bone marrow into circulation after a few days and enter connective tissue compartment to differentiate into macrophages |
| function of monocytes | phagocytose dead + disrupted pathogen cells (especially Ig/complement marked ones),release cytokines + chemokines inducing inflammation AND act as APC |
| what do monocytes do if the substance is too large for a single macrophage | fuse to form large foreign body |
| epitopes | smaller antigenic units |
| where are epitopes placed | membrane bound major histocompatibility complex antigens II (MHC II also known as class II human leukocyte antigens/ class II HLA) |
| difference between neutrophils and monocytes | neutrophils are short term but monocytes are long term |
| dendritic cells function (DC) | activate naive T lymphocytes to initiate adaptive immune response |
| characterisation of dendritic cells (DC) | ability to process + present antigens to CD4+ and CD8+ T lymphocytes, activate T lymphocytes from naive state and the ability to dictate T lymphocytes future function and differentiation |
| clusters of differentiation (CD) | surface molecules defining the origin and function of cells |
| how do WBCs travel through the body | lymphoid system |
Created by:
kablooey
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