The Clotting System Yields Fibrin Generated Mediators of Inflammation

Another enzymatic cascade that is triggered by damage to blood vessels yields large quantities of thrombin. Thrombin acts on soluble fibrinogen in tissue fluid or plasma to produce insoluble strands of fibrin and fibrinopeptides. The





Endothelial damage

Activation of Hageman factor

Activated dottmg cascade


Fibrinopeptides + fibrin clot *

Fibrin degradation

Activated fibrinolytic system


T Vascular permeability Vasodilation Pain

Smooth-muscle contraction

TVascular permeability Neutrophil chemotaxis

Complement activation

FIGURE 15-10

Tissue damage induces formation of plasma enzyme mediators by the kinin system, the clotting system, and the fibrinolytic system. These mediators cause vascular changes, among the earliest signs of inflammation, and various other effects. Plasmin not only degrades fibrin clots but also activates the classical complement pathway.

insoluble fibrin strands crisscross one another to form a clot, which serves as a barrier to the spread of infection. The clotting system is triggered very rapidly after tissue injury to prevent bleeding and limit the spread of invading pathogens into the bloodstream. The fibrinopeptides act as inflammatory mediators, inducing increased vascular permeability and neutrophil chemotaxis.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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