Cell-derived Mediators of Inflammation Flashcards
cell-derived mediators are normally located
sequestered in intracellular granules
cell derived mediators are secreted by ______ or synthesized ____
granule exocytosis; de novo in response to a stimulus
what cell-derived mediators are synthesized de novo
prostaglandins and leukotrienes, cytokines
the major cell types that produce mediators of acute inflammation are
sentinels that detect invaders and damage in tissues (macrophages, dendritic cells, and mast cells)
______ can also be induced to elaborate some of the mediators
platelets, neutrophils, endothelial cells, and most epithelia
they fall into 4 major categories which are
vasoactive amines
arachidonic acid metabolites
cytokines
chemokines
what are the vasoactive amines
histamine and serotonin
vasoactive amines are responsible for
immediate and shor-lived responses in inflammation including vasodilation, increased vascular permeability, and smooth muscle contraction in the respiratory and digestive tract
are vasoactive amines stored?
in molecules in cells and are therfore among the first mediators to be released during inflammation
where are mast cells normally present
in tissue adjacent to vessels
where is histamine found
in mast cells, in blood basophils and platelets
histamine is stored in mast cell granules and is released by mast cell degranulation in response to a variety of stimuli including
physical injury
binding of antibodies
products of complement called anaphylatoxins
binding of antibodies to mast cells does what
underlies immediate hypersensitivity reactions
anaphylatoxins include
C3a and C5a
_______ bind to specific receptors on mast cells and trigger signaling pathways that induce rapid degranulation
antibodies and complement products
______ may also trigger release of histamine
neuropeptides (substance P) and cytokines (IL-1, IL-8)
______ is a preformed vasoactive mediator present in platelets and certain neuroendocrine cells
serotonin
primary function of serotonin
neurotransmitter in the GIT
serotonin is also a _____
vasoconstrictor
histamine cellular sources
mast cells, basophils
histamine effect
vasodilation, increased vascular permeability (edema)
serotonin cellular sources
platelets, mast cells of rodents
serotonin efects
vasodilation, increased vascular permeability
______ are produced from arachidonic acid
lipid mediators prostaglandins and leukotrienes
arachodonic acid is present in
membrane phospholipids
lipid mediators stimulate
vascular and cellular reactions in acute inflammation
AA is released from membrane phospholipids through the action of
cellular phospholipases (mainly phospholipase A2)
what are eicosonoids
AA derived mediators (derived from 10 carbon fatty acids)
eicosonoids are synthesized by
cyclooxygenases and lipoxygenases
cyclooxygenass produce
prostaglandins
lipoxygenases produce
leukotrienes and lipoxins
eicosonoids bind to ______ on many cell types and can mediate virtually every step of inflammation
G protein coupled receptors
prostaglandins are produced by
mast cells, macrophages, endothelial cells, and many other cell types
prostaglandins are involved in
vascular and systemic reactions of inflammation
most important prostaglandins in inflammation
PGE2, PGD2, PGI2 (prostacyclin), TxA2 (thromboxane A2)
PGI2 cellular sources
endothelium