Acute Inflammation Flashcards
Define acute inflammation
Series of protective changes occurring in living tissue as a response to injury
Signs of inflammation
Redness
Heat
Swelling
Pain
Causes of acute inflammation
Pathogenic organisms e.g. bacteria, fungi, viruses, parasites
Trauma and injury to tissue
Chemical upset to stable environment
Extreme physical condition e.g. radiation
Dead tissue
Hypersensitivity
What is microcirculation
Capillary beds fed by arterioles and drained by venues
Extracellular space and fluid and molecules within it
Lymphatic channels and drainage
Steps in acute inflammation
Change in vessel radius
Change in permeability of vessel wall
Movement of neutrophils from vessel to extravascular space
Local changes in vessel radius
Arteriolar constriction
Arteriolar dilation
Relaxation of vessel smooth muscle
Why increase radius+flow?
Increased local tissue blood flow
Results in observed redness and heat
Brings more white blood cells
Effects of increased permeability
Rate of flow slows (stasis) which produces a change in flow characteristics
Fluid loss - increased viscosity
Exudation - net movement of plasma from capillaries to extravascular space
What is leaked is fluid rich protein which includes immunoglobulin ad fibrinogen, known as exudate
Effects of exudation
Oedema forms - an accumulation of fluid in extravascular space.
Swelling of tissue in acute inflammation, swelling causes pain and reduces function
Phases of emigration of neutrophils
Margination: Neutrophils move to endothelial aspect of lumen
Pavementing: neutrophils adhere to endothelium
Emigration: Neutrophils squeeze between endothelial cells to extravascular tissues (active process)
Ideal outcome of acute inflammation
Inciting agent isolated and destroyed Macrophages move in from blood and phagocytose debris; then fuck off Epithelial surfaces regenerate Inflammatory exudate filters away Vascular changes return to normal Inflammation resolves
Benefits of acute inflammation
Rapid response to non specific insult Transient protection of inflamed area Neutrophils destroy organisms and denature antigen for macrophages Plasma proteins localise process Resolution and return to normal
Outcomes of acute inflammation
Resolution
Suppuration
Organisation
Chronic Inflammation
What do neutrophils do?
Mobile phagocytes recognise foreign antigen, move towards it by process of chemotaxis, adhere to organism
Granules possess oxidants and enzymes, the contents are released and they phagocytose and destroy foreign antigen
Consequences of neutrophil action
They die when granule contents are released and produce a soup of fluid, bits of cell, organisms and endogenous proteins i.e. pus
Might extend into other tissues, progressing the inflammation
Role of plasma proteins in inflammation
Fibrinogen is a coagulation factor which forms fibrin an clots exudate.
Localises inflammatory process
Immunoglobulins in plasma specific for antigen, humour immune response
Mediators of acute inflammation
Molecules on endothelial cell surface
Molecules released from cells
Molecules in the plasma
Collective effects of mediators
Vasodilation Increased permeability Neutrophil adhesion Chemotaxis Itch and pain
Immediate systemic effects of inflammation
Pyrexia (raised temperature)
Feel unwell: malaise, anoexia, nausea, abdominal pain and vomiting in kids because they vomit at everything
Neutrophilia - raised white cell count
Longer term effects of acute inflammation
Lymphadenopathy (regional lymph node enlargement) as part of immune response
Anaemia
Weight loss
Outcomes of acute inflammation: suppuration
Pus formations and pyogenic membrane surrounding pus
Outcomes of acute inflammation: abscess
Collection of pus under pressure
Single local or multiloculated
Points and discharges
Collapses - healing and repair
Where else can you find pus?
Empyema - in a hollow viscus e.g. gall bladder
Pyaemia - discharge into blood stream
Outcomes of acute inflammation: organisation
Granulation tissue characteristic
Healing and repair
Leads to fibrosis and formation of a scar
