Primary and secondary injury
1. Mast cells are the first activated. Sit in the capillary bed with WBCs, they release histamine and bradykinin that causes vasodilation, increasing permeability, creating swelling (histamine and bradykinin = pain)
2. Arterioles vasodilate engorging the capillaries, which separates the endothelial cells which further increases permeability (swelling). The compression caused by accumulation of fluid decreases oxygen
3. Chemotaxis means cell signaling (mast cells are chemotactic to WBC)
4. WBC=neutrophils and monocytes =phagocytes
5. Neutrophils are microphages and destroy anything they come in contacts with
6. Monocytes only clear out dead debris
7. Hypoxia and phagocytosis = secondary injury