Exam 1: Acute inflammation Flashcards
the vascular events of the acute inflammatory response involve three main processes
- changes in vessel caliber and, consequently blood flow
- increased vascular permeability
- formation of the fluid exudate
vasodilation is induced by the action of several mediators, notably, _____
histamine, on vascular smooth muscle
during inflammation, all capillaries are
open!
increased vascular permeability allows
proteins to escape between cells; so much more fluid leaves the vessles than is returned to them
net escape of protein-rich fluid is called
exudation
transudate
a fluid low in protein and produced primarily by an increase in hydrostatic pressure or decreased blood osmotic pressure without a change in permeability
what causes the increase in vascular permeability of postcapillary interendothelial spaces in acute inflammation
2 mechanisms:
contraction of endothelial cells elicited by chemical mediators
endothelial injury, resulting in endothelial cell necrosis
contraction of endothelial cells elicited by chemical mediators is called
immediate transient response because it occurs rapidly after exposure to the mediator and is usually short-lived
a delayed response may start ____ hours after injury and lasts for up to ____ hours
1-3 hours; 12 hours
endothelial injury, resulting in endothelial cell necrosis caused by
severe injuries or action of microbes and microbial toxins that target endothelial cells; leakage starts immediately and is sustained several hours until the damaged vessels are thrombosed or repaired
proteins present in exudate include
immunoglobulins, which may be important in the destruction of invading microorganisms, and coagulation factors, asuch as fibrinogen, which reults in fibrin deposition on contact with the extravascular tissues
in blood vessels larger than capillaries, blood cells flow in the
center of the lumen (axial flow) while plasma flows near the wall
margination
as blood flow slows, blood cells begin to flow nearer to the vessel wall
Rolling (pavementing) of leukocytes
along the surface of the vascular epithelium
adhere
line up on surface of vascular endothelium
adherance is the result of
interaction between leukocyte surface molecules and endothelial cell adhesion molecules
these leukocyte and endothlial cell adhesion molecules are also called
selectins and integrins (cell surface molecules that play a role in cell to cell or cell to matrix interactions)
after adherance occurs, the next step is
leukoctye emigration into the extravascular space
what orchestrate this cellular event
cytokines (mainly TNF-alpha, IL-1) secreted by macrophages
the changes in blood flow and vascular permeability are quickly followed by
an influx of leukocytes into the tissue
these leukocytes perform the key function of
eliminating ooffending agents
the most important leukocytes in typical inflammatory reactions are
ones capable of phagocytosis (neutrophils and macrophages)
neutrophils predominate
6-24 hours in early inflammatory infiltrate
neutrophils later replaced by macrophages
24-48 hours
once in tissue, neutrophils lifespan is
only a few hours to 2-3 days and must be constantly replaced
when neutrophils die
most die locally, but some leave site via lymphatics
phagocytosis involves 3 sequential steps
- recognition and attachment of the particle to be ingested by the leukocyte
- engulfment, with subsequent formation of a phagocytic vacuole
- killing or degradation of the ingested material
microorganisms are opsonized by what
immunoglobulins or complement components
bacterial endotoxins activate complement via
alternative pathway
alternative pathway generates _____ which has opsonizing properties
C3b
if antibody binds to bacterial antigens, this can activate complement via
the classical pathway, aslo genrating C3b
binding of immunoglobulins to microorganisms by their Fab components leaves teh _____ exposed
Fc
neutrophils and macrophages have surface receptors for
Fc fragment; consequently bind to the micro-organisms prior to ingestion
after a particle is bound to phagocyte recepors, ______ flow around it
extensions of the cytoplasm (pseudopods)
the plasma membrane pinches off to form a
phagosome (vesicle) that encloses the particle
phagosome then fuses with a ________
lysosomal granule, resulting in discharge of granules contents into the phagolysosome
killing of microbes in phagocytes is accomplished by
reactive oxygen species; reactive nitrogen species mainly derived from nitric oxide, lysosomal enzymes destroy phagocytic debris
