Topic overview

Start with the big picture

Inflammatory mediators include preformed vasoactive amines such as histamine and serotonin, and newly synthesized arachidonic acid metabolites such as prostaglandins, leukotrienes, and lipoxins. Cytokines and chemokines activate endothelium and direct leukocyte recruitment, while complement contributes anaphylatoxins, chemotaxis, opsonization, and cell lysis. Other pathways—including coagulation and fibrinolysis, the kallikrein-kinin system, nitric oxide, and platelet-activating factor—also shape vascular responses and inflammation. Reactive oxygen species help kill microbes but can injure tissue. The topic’s structure moves from mediator families to their characteristic sources and actions, providing a framework for comparing how they contribute to defense, symptoms, and tissue effects.