Inflammation II Flashcards
What are the two major processes of phagocytosis?
- Recognition and attachments via complement
2. Engulfment
What is the function of complement?
Attach to microbes and macrophages
What is the process of engulfment?
Pseudopods surround object, forming, phagosome fusing with lysosome
Phagosome + lysosome = ?
Phagolysosome
What are the two types of mechanisms of microbe killing?
- Oxygen dependent
2. Oxygen independent
What are the three steps of oxygen dependent killing?
- Oxygen is reduced to superoxide via NADPH oxidase
- Superoxide is then converted to H2O2 by superoxide dismutase
- Myelo-peroxidase from PMNs granules catalyzes rxn b/t Cl and H2O2, forming HOCl
What are the oxygen-independent ways to kill microbes? (2)
Leukocytes granule proteins, and enzymes
What are the four outcomes of leukocyte activation?
- Production of arachidonic acid metabolites
- Degranulation and secretion of lysosomal enzymes
- Secretion of cytokines
- Modulation of leukocyte adhesion molecules
Where do mediators come from? What is their function?
plasma or granules of cells
Bind to specific receptors on target cells to stimulate other cell response
What are the three sequential phases of chemical mediators that leukocytes express?
- Initiation
- Amplification
- Termination
Why are mediators short lived?
To prevent over reaction, since most have potential to cause harm
What are the two major vasoactive amines? What are their functions (3)?
Histamine and serotonin
- arteriolar dilation
- constriction of large arteries
- Increase permeability of postcapillary venules
Where are vasoactive amines stored?
Preformed granules of mast cells or others
What are the first mediators likely to be released in response to damage?
Vasoactive amines
What stimulates mast cells? (5)
Trauma Platelet aggregation IgE activation Complement Cytokines
What are the three plasma protein systems?
Complement
Kinin
Clotting
What activates the classical pathway of complement activation?
binding of an IgG or IgM complex to C1 (“GM makes C1assic cars”)
What activates the alternate pathway of complement activation?
C3 directly activated by bacterial endotoxins, or aggregated IgA
What activates the lectin pathway of complement activation?
C1 activation by binding of mannose-binding lectin to carbs on microbes
What is the essential pathway of complement activation (where all three pathways converge)?
C3 activation (cleavage)
What is the function of C3a, C4a, and C5a?
Stimulate histamine release from mast cells
What is the function of C5a specifically?
chemotaxis of monocytes and granulocytes via increased expression of leukocytes CAM which activates lipoxygenase pathway
What is the function of C3b specifically?
Opsonization with recognition by receptors on PMNS
What is the function of C5-9?
Membrane attack complex
What is the function of Factor XII (Hageman factor)? How is it activated?
Triggers the kinin system, fibrinolytic system, and the clotting cascade
Activated by direct contact with endotoxins, collagen, or basement membrane
Activated Hageman factor (XII) does what in the kinin system, specifically?
Converts prekallikrein to Kallikrein
What is the function of Kallikrein after it is activated via Hageman factor (XII)?
amplifies hageman factors activation
Cleaves kinins, including bradykinin
Converts plasminogen to plasmin
What is bradykinin?
A short lived vasoactive peptide that increases vascular permeability, andcauses pain
What inactivates bradykinin?
Plasma kininase
What is the coagulation-fibrinolytic system?
Cascade of reaction resulting in a fibrin clot which is then dissolved by the fibrinolytic system
What is the function of thrombin?
Cleaves fibrinogen to insoluble fibrin
Why is thrombin significant in terms of the inflammatory system?
Links the coagulation system and the inflammatory system
What is the function of plasmin? (2)
Lyses fibrin clots to form fibrin split products
Cleaves C3 to C3a
What activates Hageman factor (XII)?
Collagen, basement membrane, activated platelets