Inflammation Flashcards
What is inflammation?
A non-specific response to cellular injury designed to remove the cause and consequence of injury
What are the four main signs of acute inflammation?
Swelling/oedema
Redness
Heat
Pain
What is the immediate response to damaged tissue?
- Inflammatory signals:
- Non-apoptotic cell death
- Detection of foreign material - Vasodilators released:
- Histamine
- Nitric Oxide - Vascular changes:
- Increased permeability
- plasma leakage
What is exudate?
A fluid barrier:
Fluid, proteins and cells that have seeped out of a blood vessel
How does cell recruitment occur?
- Chemokines are produced
- Chemokines diffuse out and form a gradient
- Leukocytes expressing complementary chemokine receptors migrate to the site
What is neutrophil extravasation?
- Neutrophils detect damage by detecting cytokines which causes the upregulation of adhesion molecules
- Integrins on the surface of neutrophils become active which causes adhesion to the endothelial surface
- Diapedesis occurs after where neutrophils squeeze through the gaps produces in the endothelial lining by rearranging the shape of it’s exoskeleton
What do neutrophils do at the site of inflammation?
- They recognise the pathogen using TLR4 AND CD14 receptors to detect lipopolysaccharides present in gram-negative bacteria
- Pathogens are then cleared by phagocytosis or netosis (engulfing the pathogen in a net of DNA extruded from the neutrophil)
- Cytokines are then secreted to activate and recruit other immune cells
How is an acute inflammation resolved?
- Pathogens wont be detected by immune cells
- Nuetrophils and inflammatory mediators (Nitric oxide and histamine) have a short half life so degrade
- Macrophages come and engulf cellular debris
- The wound is finally healed/repaired
What are the benefits of macrophages?
- Phagocytic
- Cytotoxic (but can damage surrouding tissue)
- Anti-inflammatory
- Wound repair
What are the negatives of macrophages?
- Cytotoxicity damages cells surrounding pathogen
- Can be inflammatory
- Pro-fibrotic (causes scarring)
What are the positive and negative outcomes of acute and chronic inflammation?
Positives:
- Clear inflammatory agent
- Remove damaged cells
- Restore normal tissue function
Negatives:
- Excess tissue damage can occur -> scarring
- Loss of organ function -> organ failure
What are the consequences of inflammation?
- Broncho-pneumonia
- Scarring
- Wound healing in sensitive tissues