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“Pathophysiology – Medical dictionary

INFLAMMATORY RESPONSE The inflammatory response is a sequential reaction to cell injury. It neutralizes and dilutes the inflammatory agent, removes necrotic materials, and establishes an environment suitable for healing and repair. The term inflammation is often but incorrectly used as a synonym for the term infection. Pathophysiology 26 Inflammation is always present with infection, but infection is not always present with inflammation. However, a person who is neutropenic may not be able to mount an inflammatory response. An infection involves invasion of tissues or cells by microorganisms such as bacteria, fungi, and viruses. In contrast, inflammation can also be caused by nonliving agents such as heat, radiation, trauma, and allergens. The mechanism of inflammation is basically the same regardless of the injuring agent. The intensity of the response depends on the extent and severity of injury and on the reactive capacity of the injured person. The inflammatory response can be divided in to:- 1) Vascular response, 2) Cellular response, 3) Formation of exudates 4) Healing. 1) VASCULAR RESPONSE After cell injury, arterioles in the area briefly undergo transient vasoconstriction. After release of histamine and other chemicals by the injured cells, the vessels dilate. This vasodilatation results in hyperemia (increased blood flow in the area), which raise filtration pressure. Vasodilatation and chemical mediators cause endothelial cell retraction, which Pathophysiology 27 increases capillary permeability. Movement of fluid from capillaries into tissue spaces is thus facilitated. Initially composed of serous fluid, this inflammatory exudates later contains plasma proteins, Primarily albumin. The proteins exert oncotic pressure that further draws fluid from blood vessels. The tissue becomes edematous. This response is illustrated in figure 2.1.