Acute inflammation

Acute Inflammation is a rapid and early response of the body to injury or infection, aimed at delivering immune cells and molecules to sites of tissue damage. It is a critical component of the body's immune response, initiating the process of healing and repair. Acute inflammation is characterized by pain, redness, heat, swelling, and sometimes loss of function, which are collectively known as the five cardinal signs of inflammation.

Causes

Acute inflammation can be triggered by a variety of causes, including:

• Pathogens (bacteria, viruses, fungi, parasites)
• Physical injuries (cuts, abrasions, burns)
• Chemical irritants
• Foreign bodies (splinters, dirt)
• Immune reactions (hypersensitivity reactions)

Pathophysiology

The process of acute inflammation begins with the recognition of harmful stimuli by sensor molecules present on or within host cells. This recognition triggers a series of biochemical events that lead to the activation of the inflammatory response.

1. 1. 1. Vascular Changes###

Initially, there is a brief period of vasoconstriction, followed by vasodilation of the microvessels at the injury site, leading to increased blood flow and the characteristic redness and heat. Increased vascular permeability allows plasma proteins, including antibodies and clotting factors, and white blood cells to exit the bloodstream and enter the affected tissue.

1. 1. 1. Cellular Events###

Leukocytes, especially neutrophils, are among the first immune cells to arrive at the site of inflammation, followed by monocytes which differentiate into macrophages. These cells are responsible for phagocytosing pathogens and dead cells. The release of cytokines and chemokines by injured or infected cells and arriving leukocytes coordinates the inflammatory response, promoting the removal of the cause of injury and the initiation of the healing process.

Resolution

The resolution of acute inflammation involves the cessation of leukocyte recruitment, the removal of inflammatory mediators and debris, and the repair of injured tissue. Failure to resolve inflammation can lead to chronic inflammation, which is associated with various diseases, including arthritis, asthma, and atherosclerosis.

Clinical Significance

Acute inflammation is a protective and localized response, essential for wound healing and fighting infections. However, when inflammation is excessive or inappropriately directed against the body's own tissues, it can cause tissue damage and contribute to disease. Conditions such as allergies, autoimmune diseases, and sepsis are examples where the inflammatory response plays a central role in the pathology.

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