What is the Definition of acute inflammation?
•Series of protective changes occurring in living tissue as a response to injury.
What are the important signs of inflammation?
•Rubor - redness
•Calor - heat
•Tumor - swelling
•Dolor - pain
•Loss of function
What are the Causes - aetiology -
of acute inflammation?
•Mechanical - trauma - injury to tissue.
•Chemical - upset stable environment
•Physical - extreme conditions
Outline some feutures of acute inflammation?
•Series of microscopic events
•Localised to affected tissue
•Take place in the microcirculation
•Result in the clinical symptoms and signs of acute inflammation - the cardinal signs
What is the microcirculation?
•Capillary beds, fed by arterioles and drained by venules.
What are the overall steps in acute inflamation?
•Changes in vessel radius - flow
•Change in the permeability of the vessel wall - exudation
•Movement of neutrophils from the vessel to the extravascular space
Explain the changes in vessel radius in acute inflamation?
1. Transient arteriolar constriction.
2.Local arteriolar dilatation- causes increased local tissue blood flow
3. Relaxation of vessel smooth muscle
What is the advantage of increased permeability in acute inflamation?
•Locally produced chemical mediators cause an endothelial leak followed by the net movement of plasma from capillaries to extravascular space( Exudation).
What is the effect of exudation?
•Oedema is accumulation of fluid in the extravascular space
•Explains swelling of tissue in acute inflammation
•Swelling causes pain - reduce function
Describe the phases of emigration of neutraphils?
•Margination - neutrophils move to endothelial aspect of lumen
•Pavementing - neutrophils adhere to endothelium
•Emigration - neutrophils squeeze between endothelial cells - active process - to extravascular tissues.
What is the resolution of acute inflammation?
•Inciting agent isolated & destroyed
•Macrophages move in from blood and phagocytose debris; then leave
•Epithelial surfaces regenerate
•Inflammatory exudate filters away
•Vascular changes return to normal
What are the benefits of acute inflammation?
•Rapid response to non-specific insult
•Cardinal signs and loss of function
–transient protection of inflamed area
•Neutrophils destroy organisms and denature antigen for macrophages
•Plasma proteins localise process
- Resolution and return to normal
What are the outcomes of acute inflamation?
•Suppuration-formation of pus.
Inflammation at various anatomical locations
- appendix -appendicitis
•Pleural cavity -pleurisy
What do neutrophils do?
–recognise foreign antigen
–move towards it - chemotaxis
–adhere to organism
•Release granule contents
•Phagocytose & destroy foreign antigen
What are the Consequences of neutrophil action?
•Neutophils die when granule contents released.
•Produce a “soup” of fluid, bits of cell, organisms- pus.
•Might extend into other tissues, progressing the inflammation
What is the role of plasma proteins in inflammation?
•Fibrinogen - coagulation factor - forms fibrin and clots exudate - localises inflammatory process
•Immunoglobulins in plasma specific for antigen - humoural immune response
Where do mediators of acute inflmation come from?
• Endothelial cell surface membrane
• Released from cells
• In the plasma
What are the collective effects of mediators?
•Itch and pain
•Mediators had positive and negative effects
•Result is a dynamic balance
•Favours and inhibits acute inflammation
•relative to need
What are the immediate systemic effects of inflammation?
•Pyrexia - raised temperature
•Neutrophilia - raised white cell count
–bone marrow releases/produces.
What are the longer term effects?
- Lymphadenopathy which is a regional lymph node enlargement–immune response
- Weight loss - catabolic process
Explain suppuration as an outcome to acute inflamation?
–dead tissue, organisms, exudate, neutrophils, fibrin.
•pyogenic membrane(fibrin) surrounds pus
–capillary sprouts, neutrophils, fibroblasts
–Walls off pus
What is an abscess?
•Collection of pus (suppuration) under pressure
•Single locule, multiloculated
•“points” and discharges
•Collapses - healing and repair
Explain organisation as an outcome to acute inflamation?
•Granulation tissue characteristic
•Healing and repair
•Leads to fibrosis and formation of a scar
What is granulation tissue?
•“universal patch” – repair kit – for all damage
–new capillaries - angiogenesis
–fibroblasts and collagen
Explain dissemination as an outcome of acute inflammation ?
•Spread to bloodsteam - patient “septic”
•Bacteraemia - bacteria in blood
•Septicaemia - growth of bacteria in blood
•Toxaemia - toxic products in blood
What are the effects of systemic infection?
•Shock - inability to perfuse tissues
•Clinical picture of early septic shock
–tachycardia - high heart rate
–hypotension - low blood pressure
–sometimes haemorrhagic skin rash
What are the outcomes of septic shock?
•Tissue hypoxia - cell death
•Requires urgent intervention and support
–awareness and early recognition
–ability of young people to compensate
- admit to hospital and intensive care