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Why does inflammation cause swelling?
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inflammation
The main function of complement proteins is to aid in the destruction of pathogens by piercing their outer membranes (cell lysis) or by making them more attractive to phagocytic cells such as macrophages (a process known as opsonization). Some complement components also promote inflammation by stimulating cells to release histamine and by attracting phagocytic cells to the site of infection.
Swelling, also known as edema, is a primary sign of the inflammatory response triggered by tissue damage. It occurs primarily due to the accumulation of fluid in the tissues outside of the blood vessels.12
This process is driven by specific physiological changes:
- Increased Vascular Permeability: Following an injury, chemical mediatorsāsuch as histamine, prostaglandins, and various plasma proteinsāare released. These chemicals cause the walls of local blood vessels to become more permeable.31
- Fluid and Cell Migration: This increased permeability allows fluid, proteins, and white blood cells to migrate from the circulation into the site of the injury.14
- Tissue Accumulation: The resulting flood of these substances into the damaged area creates the physical swelling.1
While this response is a vital defense mechanism intended to localize injury and facilitate healing, the resulting swelling can sometimes be severe enough to restrict movement in the affected body part.124