Acute Inflammation Flashcards
How is inflammatory exudate formed?
Inflammatory exudate due to increased vessel permeability containing salts, water, small plasma proteins (fibrinogen)
What are leukocytes?
Neutrophils, monocytes & lymphocytes expressing l-selectin ligands on endothelium
How is a chemoattractant gradient formed?
Chemoattractants formed at site of infection /injury and diffuse into adjacent tissue forming a gradient
What are the signs of acute inflammation?
Redness due to increased blood flow (hyperaemia) to injury site
Swelling from fluid accumulation due to increased vessel permeability
Heat from increased blood flow and metabolic activity
Pain as release of pain mediators and pressure on nerve ends
Loss of function from excessive swelling and pain
Which factors prevent tissue healing?
Infection, Diabetes, Old Age, poor general health & nutrition
Protein / vitamin C deficiency
Drugs - corticosteroids
Extensive inury & haemorrhage, poor vascular supply
Foreign bodies, pressure, torsion, movement on wound edges (dehiscence)
Why is acute inflammation described as a local response?
All the symptoms and effects take place in the affected tissue
What is the role of selectins in acute inflammation?
Mediate rolling of neutrophils, expressed by activated endothelium
Which factors favour tissue regeneration?
Minimal destruction & cell death
Quick removal of dead tissue and foreign material
Immobilisation of wound edges
Fast infection clearance
What are the 5R’s of acute inflammation?
Recognition of injury Recruitment of leukocytes Removal of injurious agents Regulation and closure of inflammatory response Resolution / Repair of affected tissue
Which tissues have no regeneration ability?
Permanent tissues
neurons, myocardium, skeletal muscle
Heal with fibrosis, scarring and loss of function
What is haemorrhagic exudate?
Exudate formed when blood vessel rupture or trauma RBCs predominate
What is neutrophil chemotaxis?
Movement of cells through tissue, towards inflamed site guided by chemoattractants
What would be the consequence if no acute inflammation occurred?
There would be no infection control
Impaired wound and no tissue healing
Which tissues have an immediate regeneration ability?
In stable tissues
If in normal state quiescent cells are in G0/G1, injury leads to cell division, they may regenerate when injured
e.g. liver, kidney, pancreas, endothelial cells, fibroblasts
If an extensive injury, scarring is prevalent
What are the main features of fibrinuous exudate?
- Fibrin deposition derived from fibrinogen in plasma
- Large vascular leaks: fibrinogen exits blood entering
tissues - serous cavities : meningis, pleura & pericardium
- Can lead to scarring if not cleared as fibroblasts ->
collagen
What is the role of leukocytes?
Endothelial leukocytes bind to ligands on neutrophils
Low affinity interaction is disrupted by blood flow, causing repetitive binding and detaching
Rolling (mediated by sleectins) slows down
What is the purpose of acute inflammation?
Alters the body , limiting spread of infection / injury to rest of the body
Protects injured site from further infection by eliminating dead cells / tissues
Creates a healing environment
How is acute inflammation terminated?
Via antimicrobial mechanisms, inflammatory mediators
Not specific to microbes / dead tissues
Normal tissues can get damaged during inflammation - termination is vital
How is Sepsis caused?
In rare cases, systemic inflammatory reaction scan lead to sepsis which is a form of systemic inflammatory response syndrome (SIRS)
- can be widespread and have severe manifestations
Describe the vascular events of acute inflammation
- Vasodilation of small vessels due to histamine /
serotonin release by injured cells, mast cells &
macrophages - Increased blood flow to injured area results in an influx
of WBCs, fluid, oxygen, and nutrients - Increased vessel permeability (microvessels) due to
endothelial contractions results in fluid containing cells
leakage into injured tissue - Endothelial cells activated increasing adhesion
molecules