Chemical mediators
- Histamine
- Stored in granules of basophils, mast cells, platelets
- Causes vasodilation and increased capillary permeability
- Stored in granules of basophils, mast cells, platelets
- Serotonin
- Stored in platelets, mast cells, enterochromaffin cells of GI tract
- Causes vasodilation and increased capillary permeability like histamine.
- Stimulates smooth muscle contraction
- Stored in platelets, mast cells, enterochromaffin cells of GI tract
- Kinins (e.g., bradykinin)
- Produced from precursor factor kininogen as a result of activation of Hageman factor (XII) of clotting system
- Cause contraction of smooth muscle and vasodilation.
- Result in stimulation of pain
- Produced from precursor factor kininogen as a result of activation of Hageman factor (XII) of clotting system
- Complement system (C3a, C4a, C5a)
- Anaphylatoxic agents generated from complement pathway activation
- Stimulate histamine release and chemotaxis
- Final components of complement system create holes in cell membrane, causing targeted cell death by membrane rupture
- Anaphylatoxic agents generated from complement pathway activation
- Prostaglandins and leukotrienes
- Produced from arachidonic acid
- PGs cause vasodilation. LTs stimulate chemotaxis
- Produced from arachidonic acid
- Cytokines
