Stage 4 - Inflammatory Oedema

• Definition of Inflammatory Oedema

  abnormal fluid accumulation (swelling is caused by the histamine released during the inflammation process) in body tissue cavities by increased filtration of fluid into the tissues
• Role of Osmotic Pressure in Swelling

  the norm pressure grads increase + outside the capillary, balance the flow of fluid leaving + entering the vessel

  the capillary membrane is permeable to water + so water will be driven out into the interstitial fluid

  during inflammation, the capillary bed opens + blood flow increases (heat + redness)

  the larger blood vol causes an increase in bp

  the tissue fluid contains large amounts of albumin, which spikes the osmotic pressure, which along w the increased pressure forces fluid out into the interstitial fluid causing swelling
• Contibution to Tissue Clean-Up

  oedema contributes to tissue clean-up

  the swelling compresses veins + reduces venous drainage, whilst it forces open the valves of lymphatic capillaries + promotes lymphatic drainage which can collect + remove bacteria, dead cells, proteins + tissue debris better than capillaries

  = during inflammation, lymphatic vessels open up + assist in the removal of excess fluid + protein

  muscular contraction causes a pumping action of the lymph vessels + the excess fluid is removed to the subclavian veins in the neck
• Pathological Process

  can be localised swelling or generalised herat failure

  in severe cases it accumulates w in large bodily cavities - pleural cavity
• Clinical Features of Inflammatory Oedema

  general - swelling around base of spine + ankle if body fluid has increased by 15%

  local - injury, pain etc
• Inflammatory Oedema Advantages

  fluid increase in damaged tissue dilutes + modifies the action of toxins

  proteins levels increase in the tissue - inc antibodies + fibrins

  the formation of a fibrin net acts as a scaffold for inflammatory cells, preventing the spread of MOs

  circulation of the exudates into the lymphatic system assists in the development of a specific heightened immune response
• Cellular Agents of Inflammation - Neutrophils

  first responders to acute inflammation

  phagocytises pathogens + debris

  releases antimicrobial enzymes + extracellular proteins that breaks down tissue barriers to allow neutrophil migration
• Cellular Agents of Inflammation

  monocytes circulate in blood - migrate into tissues + differentiate into macrophages

  = phagocytosis + transformation into APCs to tag in T cells

  releases cytokines

  critical for both initiation + resolution of inflammation

  central to chronic inflammation
• T Lymphocytes

  originate from bone marrow

  mature in the thymus of the bone = T cells

  each T cell has a unique T cell receptor that recognises specific antigens presented by MHC mols
• Helper T Cells

  recognise antigens from all APCs

  releases cytokines to activate B cells, macrophages + cytotoxic T cells
• Cytotoxic T Cells

  recognises antigens on all nucleated cells

  kills infected/cancerous cells directly using perforin + granzymes
• Regulatory T Cells

  suppresses immune responses to maintain tolerance + prevents autoimmunity
• Memory T Cells

  persists after infection + responds quickly upon re-exposure to the same antigen
• B Lymphocytes

  originate + mature in the bone marrow

  each B cell has a unique B cell receptor = a membrane-bound antibody

  upon activation, they can differentiate into plasma cells/memory B cells
• B Lymphocytes - Plasma Cells

  produce large amounts of antiodies
• B Lymphocytes - Memory B Cells


  provide long-term immunity + rapid response on re-exposure
• Chemical Agents of Inflammation

  mols that initiate, regulate + resolve the inflammatory response

  they can be produced locally by cells or come from the plasma

  act thru receptors + often have short half-lives to tightly control inflammation
• Cell-Derived Mediators - Histamine

  released by mast cells, basophils + platelets

  function - vasodilation, increases vascular permability + bronchoconstriction
• Cell-Derived Mediators - Serotonin

  released by platelets

  function - vasoconstriction, increase vascular permeability
• Cell-Derived Mediators - Cytokines

  released by macrophages, lymphocytes ...

  evokes fever, strong neutrophil chemoattactant
• Plasma-Derived Mediators - Coagulation Factors

  activate inflammation via thrombin + fibrin degradation products

  help contains infection + tissue damage