Inflammation Flashcards
What 3 things happen in acute inflammation
- vascular changes
- increased flow
-increased permeability - cellular reactions
- extravasation of leukocytes
- migration of leukocytes to target area > recognition and phagocytosis - orchestration of chemical mediators of acute inflammation
What is the dominant cell type in acute inflammation
PMN
What is the aim of acute inflammation
To get PMN into the site of need and activation
How long does acute inflammation last for once stimulus is withdrawn
<2 days
Outline the vascular changes that occur in acute inflammation
Increased flow
1. initially, transient vasoconstriction of arterioles occurs
2. vasodilation follows, causing increased flow > accounts for heat and redness
* this is mediated by PGI2 & NO
3. eventually this slows down because of increased vascular permeability > leading to stasis > oedema
4. 4. with slowing, leukocytic margination appears, a prelude to the cellular events
What are the 4 main reasons there is an increase in permeability in acute inflammation
- Endothelial gap widening
- Cellular damage
- Increased transyctosis across endothelium
- Angiogenesis (leaky new vessels)
What 5 chemical mediators are involved in increasing permeability of venules during the acute inflammatory reaction
- platelet activating factor (PAF)
- bradykinin
- histamine
- leuokotrienes
- Substance P
In what 3 situations might vascular permeability account for oedema in
- acute anaphylaxis
- adult respiratory distress syndrome
- serum sickness
What mediates arteriolar dilatation in early stages of acute inflammation
- prostacyclin (PGI2)
- nitric oxide (NO)
How does endothelial gap widening occur
- mediated by histamine, bradykinin, PAF, leukotrienes, substance P ! only involves venules; capillaries & arterioles unaffected
- cytoskeletal reorganization ! mediated by IL-1 and TNF-a
How does cell damage contribute to increased permeability
- From direct injury > cell dies > release above mediators > affect the entire microcirculation
- From leukocytes aggregating and releasing toxic oxygen free radicals and proteolytic enzymes
How does transcytosis increase vascular permability
via vesicles and vacuoles of the vesiculovacuolar organelle
* some growth factors, e.g. vascular endothelial growth factor may cause vascular leakage by increasing number and size of these channels
