Acute inflammation Flashcards
Signs of acute inflammation
- Heat
- Redness
- Swelling
- Pain
- Loss of function
Morphologic hallmarks of acute inflammation
- Dilation of blood vessels
- Activation and recruitment of leucocytes
- Active exudation of fluid in the extravascular tissues
Stages of acute inflammation
- Recognition of the injurious agent
- Reaction of blood vessels
- Recruitment of leucocytes
- Removal/clearance of the agent
- Regulation of the response
- Repair/resolution
Possible outcomes of acute inflammation
- Complete resolution: clearance of the offending agent and regeneration.
- Scarring/fibrosis: connective tissue growth into the area of damage or exudate. This occurs after substantial tissue destruction.
- Progression to chronic inflammation: unresolved inflammatory process due to either persistence of the injurious or some interference with the normal process of healing.
Mediators in acute inflammation
- Vasoactive amines
- Inflammatory lipids
- Complement
- Cytokines
- Others: kinins, chemokine, nitric oxide, coagulation cascade, PAF.
Vasoactive amines
e.g. histamine, serotonin
Produced/released by mast cells, basophils and platelets
Inflammatory lipids
e.g. prostaglandins, leukotrienes
Produced by mast cells and leucocytes
Complement
e.g. C5a, C3a
Plasma proteins produced in the liver
Cytokines
e.g. IL-1, TNF, IL-6
Produced by macrophages, endothelial cells, mast cells
Role of mediators in acute inflammation
- Vasodilation is caused by inflammatory lipids
- Increased vascular permeability is caused by vasoactive amines, complement, inflammatory lipids and cytokines
- Leucocyte recruitment and activation is caused by inflammatory lipids, complement and cytokines
- Pain is caused by inflammatory lipids
- Tissue damage is caused by neutrophil granula content e.g. enzymes and reaction oxygen species (ROS) produced by neutrophils and leucocytes
Acute phase response
characterised by different systemic effects of acute inflammation (and other conditions) including pyrexia, leucocytosis, metabolic changes
Acute phase proteins
Biomarkers of inflammation
How pyrexia arises
Transudate
extravascular filtrate of protein and cell poor fluid.
- This is due to increased hydrostatic pressure/decreased colloids-osmotic pressure or a combination of both.
- Transudate accumulations in body cavities and extracellular compartments.
- The fluid appears grossly clear and watery.
Describe the nature of this fluid, seen in a dog with ascites
Transudate
Exudate
extravascular fluid that has a high protein concentration and can contain leucocytes.
- Its presence implies the existence of an inflammatory process that has increased the permeability of blood vessels.
Serous inflammation
inflammation with exudation of fluid with a low conc. of plasma protein and no-low numbers of leucocytes
Fibrinous inflammation
inflammation with exudation of fibrinogen and fluid, and formation of thick, friable, loosely adherent fibrin.
Purulent inflammation
inflammation with production of pus, viscous to creamy liquid; an exudate consisting of degenerated and necrotic neutrophils, debris and fluid.
Typically associated with bacteria infection.
Haemorrhagic inflammation
inflammation with vascular damage, loss of integrity of endothelium and/or extensive tissue necrosis with leakage of red blood cells.
This type of acute inflammation reflects a severely inciting stimulus e.g. parvovirus
