Inflammation - Chemical Mediators Flashcards
What are the sources of chemical mediators of inflammation?
CELLS and PLASMA
What are the vasoactive amines?
Histamine and Serotonin
Describe the source and action of HISTAMINE as a vasoactive amine.
i. Preformed in mast cells, basophils, and platelets
ii. Released by mast cells in response to binding by IgE, cellular damage, or complement fragments C3a and C5a
iii. Vasodilation, increased vascular permeability via endothelial contraction
Describe the source and action of SEROTONIN as a vasoactive amine.
i. Preformed in platelets
ii. Released in response to platelet activation
iii. Vasodilation, increased vascular permeability via endothelial contraction
What is the source of arachidonic acid?
Phopholipase breaks down cell membranes to yield arachnidonic acid.
What are the proinflammatory AA metabolites?
Prostaglandins
Formed by cyclooxygenase reactions.
Mediate fever and pain via COX1 and COX2 receptors
Leukotrienes
Formed by lipooxygenase reactions.
Stimulate vasoconstriction, increased vascular permeability
What are the ANTI-inflammatory AA metabolites?
Lipoxins
Produced by lipooxygenase reactions.
Inhibit inflammation
Inhibit leukocyte recruitment and cellular components of inflammation.
Describe the major actions of PAF in mediating inflammation.
PAF (Platelet Activating Factor)
i. Increases vascular permeability
ii. Stimulates aggregation/activation of platelets
iii. Stimulates leukocytes aggregation, adhesion, and chemotaxis.
Describe the major actions of FREE RADICALS in mediating inflammation.
Free Radicals
i. Endothelial cell damage and vascular leakage
ii. Injury to other cells
iii. Inactivation of antiproteases
iv. Increased tissue destruction
Describe the major actions of NO in mediating inflammation.
NO (Nitric Oxide)
i. Vasodilation
ii. Inhibits inflammatory response (reduces platelet aggregation and inhibits leukocyte recruitment).
iii. As a free radical, it kills microbes
What are the main cell types that produce cytokines?
Phagocytes and lymphocytes
What are the 2 major cytokines involved in acute inflammation and be able to describe their LOCAL and SYSTEMIC effects.
IL-1 and TNFa
i. Induce acute-phase response.
ii. Endothelial activation
Synthesis of adhesion molecules, other cytokines, growth factors, eicosanoids, and NO.
iii. Fever
iv. Stimulate fibroblasts
What 3 pathways activate the Complement System?
Lectin Pathway, Alternative Pathway, Classical Pathway
How does the Lectin Pathway activate the complement system?
Plasma mannose-binding lectin binds to sugars on microbes.
How does the Alternative Pathway activate the complement system?
Contact with microbial surfaces and polysaccharides
