Unit 3 - 3.1-3.4 Flashcards
The cellular response to a mediator may vary depending on:
the mediator concentration
For every mediator, there is:
one or more inhibitor
Do mediators have long or short lives?
short
What can change the effects of mediators?
species, tissue locaion
Are almost all chemical mediators endogenous or exogenous?
endogenous
What are the first mediators released?
histamine and serotonin
How is histamine stored?
as granules in mast cells
What are the effects of histamine?
pain, smooth muscle contraction, arteriole dilation, increased permeability of venules
How is serotonin stored?
as granules in platelets
What are the effects of serotonin?
smooth muscle contraction, dilation of arterioles, increased permeability of venules, stimulation of fibroblasts
What cleaves kininogens?
kallikreins
How are kinins carries in the blood?
as inactive kinogens
What activates prekallikreins?
hageman factor (XII), plasmin, and neutrophil enzymes
What is the most important kinin?
bradykinin
What does bradykinin do?
pain, increased vascular permeability, vasoconstriction/vasodilation
What product from the digestion of fibrin can also increase permeability and vasoconstriction?
fibrinopeptides
Circulating kininases inactive:
kinins
Consists of nine proteins that are produced in the liver and other cells, and circulate in the plasma in an inactive form
complement
assembles to form a membrane attack complex that perforates cells
C1-C9
Which complement fragments are anaphylatoxins (have proinflammatory effects)
C3a, C4a, C5a
Which complement fragment opsonizes bacteria?
C3b
platelet aggregation and vasoconstriction
thromboxanes (A1, A2)
main function is vasodilation; PGI2 also inhibitor of platelet aggregation
Prostaglandins (PGE2, PGI2)
Causes vascular leakage, vasoconstriction or vasodilation, chemotaxis
Leukotriene pathway (5-lipoxygenase)
Antiinflammatory
Lipoxin pathway
What are the three potential pathways for development of eicosanoids?
- cycolooxygenase
- leukotriene
- lipoxin
Formed from phospholipids after the arachidonic acid is removed
platelet activating factors (PAF)
What produces PAF?
leukocytes, mast cells, endothelium, platelets, some epithelial cells
When are PAFs most commonly seen?
allergic reactions
acute phase response cytokine - released due to burns or tissue damage
IL-6
How does IL-6 increase temperature?
by increasing energy mobilization
very powerful, causes tumor necrosis, induces acute and chronic inflammation
TNF alpha
induce movement of cells into sites of inflammation
chemotaxins
have effects on inflammation by damaging membranes and DNA
free radicals
any molecule generated in an area of inflammation that modules the inflammatory process in some way
chemical mediator
What does it mean that most mediators are endogenous?
produced by the cells involved in the inflammatory process