PP 2 Acute Inflammation Flashcards
Inflammation definition
Response of living tissue to injury
Features of acute inflammation
Immediate
Short duration
Innate/normal
Stereotyped - same regardless
Limits damage
Causes of acute inflammation
Trauma/foreign body
Micro organisms/infections
Hypersensitivity - allergies
Other illnesses e.g. cancer, necrosis
Clinical signs of acute inflammation
Rubor: redness
Tumour: swelling
Calor: heat
Dolor: pain
Loss of function
How long does vasoconstriction last and what is it?
Decreased diameter for a few seconds
How does calor arise?
Vasodilation
Increased diameter
More blood
How does rubor arise?
Vasodilation
Increased diameter
More blood
What occurs in vasodilatation?
1- arterioles dilate
2- flow accelerates into capillaries
3- capillary pressure increases
4- increases delivery of fluids tend leukocytes to injury site
What does increased permeability of walls cause?
- Fluid + cells to move out of vessel
- causing oedema
- increase the viscosity of blood > stasis
Stasis meaning
Reduced blood flow in vessels
Where does interstitial fluid drain to?
Lymph nodes
Stimulates adaptive immune response
Types of interstitial fluid
Exudate
Transudate
Difference between exudate and transudate
Exudate - protein rich that develops in inflammation
Transudate - lacks proteins + occurs in normal vessels
How does exudate form?
- Tissue injury > release of vasoactive mediators
- arteriolar dilation > ^ capillary hydrostatic pressure
- inflammatory mediators cause ^ permeability of walls
- fluid + plasma proteins diffuse into interstitial space
- osmotic pressure increase = holds fluid in the interesitial spae
Examples of proteins in exudate
Fibrin- mesh limits spread of toxin
Immunoglobulin- from adaptive immune response
What does exudate formation occur in?
Inflammation
Vascular permeability in exudate formation
Increased permeability
Vascular permeability in transudate formation
Unchanged
How does transudate form?
Fluid moves out due to:
Increased hydrostatic pressure
Decreased oncotic pressure
What does transudate formation occur in?
Hepatic failure
Heart failure
Renal failure
Causes of increased wall permeability
- Retraction of endothelial cells
- Direct injury e.g. burns, toxins, trauma
- Leukocyte dependent injury
What are the primary WBC in acute inflammation?
Neutrophil
How do neutrophils escape vessels
1- migration: cells pushed to vessel wall
2- rolling
3- adhesion
4- emigration/diapedesis: cells move out of vessel
What are responsible for rolling in the cellular phase?
Selectins
Where are selectins found?
On activated endothelial cells
What are activated endothelial cells?
Endothelial cells which are actively doing something
What are selectins activated by?
Chemical mediators
What is responsible for adhesion in the cellular phase?
Integrins
Where are integrins found?
On neutrophil surface
Chemotaxis meaning
Directional movements towards a chemical attractant
How do neutrophils move through the intersisitum?
Chemotaxis
Examples of chemoattractants
Bacterial peptides
Inflammatory mediators - C5a, LTB4
Rearrangement of neutrophil cytoskeleton
Opsonisation meaning
Adding opsonin to pathogen to make it visible to neutrophil for phagocytosis
Examples of opsonin
C3b
C4b
IgG antibody
IgM antibody
CRP
Collectins
List the order of events that neutrophil follow to capture and kill bacterium
Chemotaxis
Activation
Margination
Diapedesis
Recognition attachment
Phagocytosis
List the stages of acute inflammation
1- stimulus
2- vascular phase
3- cellular phase
4- resolution or persistence
Steps in the vascular phase
1- vasoconstriction of arterioles
2- vasodilation of arterioles, then capillaries
3- increased permeability of blood vessels
4- increased viscosity > stasis