Acute Inflammation Flashcards
Define acute inflammation
immediate/early response to injury (minutes/days)
What are the common causes of acute inflammation?
- infection
- physical agents e.g. burns
- chemical agents
- immune responses
- tissue death from any cause
What are the consequences of acute inflammation?
- may be beneficial (e.g. bacterial killing, removal of dead tissue)
- also potential harmful effects (e.g. lung damage in pneumonia, kidney damage in acute pyelonephritis)
- may precede chronic inflammation, healing and repair
What are the main components of acute inflammation?
- Vascular response
- Inflammatory cell infiltration
- Vascular response
- vasodilation –> increased blood flow (redness, warmth)
- increased permeability –> oedema (swelling) - Inflammatory cell infiltration
- mainly neutrophils
- macrophages (during later stages)
- lymphocytes may also be involved
What are the 3 components of vascular changes in acute inflammation?
- vasodilation of arterioles
- increased blood flow through capillary bed - increased permeability (capillary bed, venules)
- protein-roch fluid escapes into intravascular space
- increased concentration of erythrocytes (congestion)
- increased blood viscosity
- reduced blood flow (stasis) - Leukocyte margination
- loss of axial streaming
- first stage in process of leukocyte migration
Describe the 4 stages of leukocyte migration and the adhesion molecules involved
Margination - movement to periphery of blood vessel - mainly related to stasis, loss of axial streaming Rolling - transient weak binding to endothelium - selectins Adhesion - firm adhesion to endothelium - integrins Transmigration - movement into extravascular space - PECAM-1, CD31
Describe the control of leukocyte migration
- interaction between receptors on leukocytes and ligands on endothelial cells
- regulation of receptor linage expression by cytokines and chemokines
What causes pain in acute appendicitis?
- neutrophils in serosa
- aggravatie nerve fibres on surface
What are the 4 bowel layers called?
mucosa
submucosa
muscularis
serosa
Define chemotaxis
List some chemotactic substances
What are the other effects of chemotactic molecules?
Chemotaxis = migration along chemical gradients Chemotactic substances - bacterial products - complement components - leukotrienes - chemotactic cytokines Other effects (facilitate migration) - leukocyte activation - endothelial cell activation
Describe the steps of phagocytosis
- recognition and attachment of particle to leukocyte
- opsonins (e.g. IgG, C3b) - engulfment
- pseudopods surround particle
- formation of phagocytic vacuole - killing and degradation
- production of reactive oxygen metabolites
- release of lysosomal enzymes
see chemical mediators table
see table
Define suppurative inflammation
also known as purulent inflammation
- formation of pus
- requires infection with pyogenic bacteria
What is pus?
- material composed of neutrophils, necrotic cells and bacteria
- complication of infection with pyogenic bacteria
What is an abcess?
- a localised collection of pus
List the 3 viral and 1 immune mediated diseases with lymphocytes rather than neutrophils
Viral infections
- acute viral hepatitis - Hep A, B, C
- viral meningitis - coxsackievirus, mumps
- viral myocarditis - coxsakievirus. echovirus
Immune mediated diseases
- autoimmune hepatitis (usually has a chronic course)
What are the 3 possible options for after acute inflammation?
- resolution
- limited/short-lived injury
- return of tissue to normal state - scarring/fibrosis
- more extensive tissue damage
- tissues with little capacity for regeneration
- abscess formation - progression to acute inflammation
What are the classical clinical features of acute inflammation?
Classical clinical features
- heat (calor)
- redness (rubor)
- swelling (tumor)
- pain (dolor)
Raised white cell count (mainly neutrophils)
- particularly high in pyogenic bacterial infection
- also present in non-infective causes (e.g. MI)
- neutrophil-rich leukocytosis in other body fluids e.g. CSG in bacterial meningitis
How can you clinically differentiate viral and bacterial meningitis?
lumber puncture
bacterial = neutrophils in CSF
viral = lymphocytes in CSF
What is the clinical application of defects in leukocyte function?
- hereditary (uncommon) e.g. chronic granulomatous disease
- acquired e.g. leukaemia
- -> predispose to bacterial infections, which may be life-threatening
Give examples of broad spectrum and targeted anti-inflammatory therapy
Broad spectrum
- NSAIDS inhibit cyclooxygenase enzymes (COX-1, COX-2) involved with arachidonic acid metabolism to produce prostaglandins
Targeted treatments
- therapies blocking specific chemical mediators or receptor-ligand interactions (e.g. anti-TNF antibodies, anti-ICAM-1)
