INFLAMMATION

All information taken directly from Understanding Zoonotic Diseases by Janet Amundson Romich. Thomson Delmar publishing

Inflammation is a reaction to any traumatic event in the body.

Ex: local injury irritation

microbe invasion toxin release

Once the initial traumatic event has occurred, a chain reaction takes place that the site of the damaged tissue.

The chain reaction includes calling beneficial cells and fluids into the injured area.

Some of the earliest changes occur in the vasculature near the damaged tissue – these changes are controlled by the nervous system and the cytokines (chemical mediators) released by blood and tissue cells.

The first response to damaged tissue is vasoconstriction (narrowing of the blood vessels) – this lasts only for a few seconds or minutes and is rapidly followed by vasodilation (widening of the blood vessels).

Vasodilation causes increased blood flow to the damaged area, which causes the redness and heat.

Vasodilation also causes the endothelial cells lining the capillaries to stretch and form gaps through which blood components can leak into the extracellular spaces.

The fluid (exudate) that escapes is typically plasma and it accumulates in the tissues causing edema (local swelling and hardness)

The accumulation of fluid, cells and cell debris signals the neutrophils to the area.

After a time, phagocytes come to the damaged area.

They clear the area of fluid, cellular debris, dead neutrophils and damaged tissue.

Lymphocytes react by producing antibodies to kill intruders directly.

TISSUE INJURYInflammation triggered by a traumatic event

VASODILATIONFollowing brief vasoconstriction, vasodilation causes increased blood flow to the damaged site providing delivery of plasma proteins and

phagocytes

INCREASED PERMEABILITYBlood components such as plasma move to the damaged site and leak

from blood vessels into tissues and extracellular spaces

MIGRATION OF PHAGOCYTESNeutrophils, macrophages and lymphocytes squeeze through gaps in the endothelial cells of capillaries and move to the damaged site in

response to chemotactic agents released by damaged tissue

PHAGOCYTOSISPhagocytes attach to and engulf foreign particles. Foreign particles are destroyed by enzymes present in the phagocytes. Lymphocytes

react in a specific manner.