Inflammation and the Acute Inflammatory Response Flashcards
Inflammation is basically
Rxn of vascularized tissue to injury
Types of edema
Exudate - inflammatory edema…high protein content, specific gravity > 1.020…from increase in blood vessel permeability that is characteristic of inflammation **contains cellular and chemical mediators critical to inflammation
Transudate - low protein content and specfic gravity < 1.012…filtrate of plasma caused by increase in hydrostatic pressure or decrease in plasma oncotic pressure…no association with vascular permeability
Vascular flow change - acute inflammation
Vasodilation…increased blood flow to affected tissue
Vascular permeability - acute inflammation
Increases in microvasculature…escape of exudate to injured tissue…blood remaining in vessels is concentrated and moves slows
2 mechanisms to increase vascular permeability
Endothelial cell contraction (retraction)
Leukocyte mediated endothelial injury
Retraction
Mainly in venules
Endothelial cells shorten, leading to widening of junctions…exudate through gaps
Rapid
Mediated by lots of chemical mediators
Leukocyte mediated endothelial injury
Mostly in venules
Leukocytes adhere to endothelial cells and become activate…release toxic substances that cause endothelial injury and detachment of cells from inner wall of blood vessels
Delayed onset
Adhesion
When stasis occurs, leukocytes within blood stream move toward inner wall of blood vessels (margination)
Rolling leads to adhesion
Adhesion molecules are mediators that bind…selectins involved in rolling, integrins promote firm adhesion
Modulation of adhesion molecules necessary to promote binding to one another
Redistribtuion of adhesion molecules from within cytoplasm to cell surface where they are available for binding example
P-selectin normally bound to Weibel-Palade bodies in endothelial cytoplasm…chemical mediators cause migration to endothelial membrane
Induction of adhesion molecule synthesis example
E-selectin…not found within endothelial cells unless induced by chemical mediator of inflammation…not immediately available
Increase in binding affinity of adhesion molecules example
LFA-1/ICAm-1 interaction…leukocyte activation leads to conformational changes of adhesion molecules
Transmigration across endothelium
Diapedesis
Leuko squeezes through gaps and into tissues…homophilic adhesion to PECAM-1 …**neutrophil is predominant cell that transmigrates in acute
Two types of chemoattractants
Exogenous - from bacteria
Endogenous - produced by injured host
Mechanism of chemotractant inducement of movement
Chemoattractant binds receptor on leukocyte membrane…activates intracellular phospholipase C which triggers series of events increased intracellular calcium…causes cross linked of actin…forms pseudopod and moves in direction of density gradient…process of pseudopod formation occurs repeatedly until it reaches sources
Phagocytosis steps
Recognition and attachment
Engulfment
Killing