Phenomenon of inflammation:
Vasodilatation: Whenever there is entry of an irritant in the body and or there is injury to the tissue the mast cells of the tissue undergo immediate degranulation liberating various chemicals such as histamine 5-hydroxytryptamine (serotonin) kinins and prostaglandins these substances also called as autacoids mediate vascular changes (vasodilatation by histamine kinins and some prostaglandins and vasoconstriction by serotonin and some other prostaglandins) In addition as a result of stimulation of nearby nerves there is vasodilatation (axon reflex ) congestion of blood in the area is called as hyperaemia which accounts for redness and the heat of inflammed area
Diapedesis: Due to vasodilation there is slowing of blood flow in the region followed by stasis In addition to stagnation of blood there is a change in capillary permeability in the area of injury that causes emigration of leucocytes by amoeboid movement through the capillary membrance (diapedesis) under normal condition blood cells occupy central zone and plasma occupies peripheral zone During inflammation WBCs fall out to occupy peripheral zone and tend to adhere to the endothelium this is identical to the cordening a disturbed area by the police substances liberated from bacteria and damaged tissues attract leucocytes and give direction to their movement this is called chemotaxis
Exudative phenomenon: Exudation is the collection of fluid during inflammation as a result of increase in capillary permeability the exudate is highly coloured and contains fibrinogen leucocytes and erythrocytes chemicaly it is rich in proteins monocytes in the exudate are converted into macrophages giant cells and histiocytes all of which are phagocytic plasma is also found in abundant in exudate it dilutes the toxin or irritant it carries immune bodies and proteins that help in modifying the course of inflammation and tissue repair respectively this exudate is the cause of the local edema or swelling that in turn presses on adjacent nerve endings contributing to sensation of pain
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