1.12
Inflammation is a protective response of tissues to injury, infection, or harmful stimuli.
It is characterized by redness, heat, swelling, pain, and sometimes loss of function.
Common causes of inflammation include:
Physical injury, such as a sprained ankle, damages ligaments and causes redness, swelling, and pain.
Chemical exposure, such as contact with caustic agents like drain cleaner, can cause chemical burns and localized inflammation.
Ischemia, or reduced blood supply, causes oxygen deprivation and cell injury; if prolonged, this results in tissue death, known as infarction, and triggers inflammation.
Immune responses, such as in allergic reactions, can trigger inflammation, as seen in allergic rhinitis. Common triggers include pollen, dust, mold, or animal dander, which can inflame the nasal passages after exposure.
Thermal extremes, like sunburn, damage skin cells and trigger inflammation—causing redness, warmth, and pain.
Foreign bodies, such as splinters, activate a local immune response, leading to swelling and tenderness at the site.
Inflammation is a fundamental, protective biological response of vascularized tissues to cellular injury, infection, or harmful stimuli. Its primary function is to eliminate the initial cause of injury, clear necrotic cells and damaged tissue, and initiate the necessary repair processes.
Cardinal Signs
Acute inflammation presents with classic signs. Redness results from vasodilation and increased blood flow. Heat is due to increased metabolism and circulation. Swelling results from the accumulation of protein-rich fluid due to increased vascular permeability. Pain arises from mediators such as prostaglandins and bradykinin, which stimulate nerve endings. Loss of function reflects the combined effects of pain, swelling, and tissue damage.
Etiology of Inflammation
Inflammation is triggered by factors that cause cellular injury. Physical trauma (e.g., fractures, lacerations) leads to cell damage and release of intracellular contents. Chemical exposure to acids, alkalis, or toxins damages cell membranes and induces necrosis. Ischemia and infarction reduce oxygen supply, causing cell death and the release of danger signals that activate inflammation.
Microbial infections (bacteria, viruses, fungi, parasites) stimulate immune responses through pathogen-associated molecular patterns. Immune reactions, such as allergies or autoimmune diseases, also produce inflammation; for example, allergen binding to IgE on mast cells releases histamine. Thermal injury from burns or frostbite damages tissue, while foreign bodies (splinters, sutures, urate crystals) trigger inflammation as the body attempts to remove or isolate them.
Inflammation is a protective response of tissues to injury, infection, or harmful stimuli.
It is characterized by redness, heat, swelling, pain, and sometimes loss of function.
Common causes of inflammation include:
Physical injury, such as a sprained ankle, damages ligaments and causes redness, swelling, and pain.
Chemical exposure, such as contact with caustic agents like drain cleaner, can cause chemical burns and localized inflammation.
Ischemia, or reduced blood supply, causes oxygen deprivation and cell injury; if prolonged, this results in tissue death, known as infarction, and triggers inflammation.
Immune responses, such as in allergic reactions, can trigger inflammation, as seen in allergic rhinitis. Common triggers include pollen, dust, mold, or animal dander, which can inflame the nasal passages after exposure.
Thermal extremes, like sunburn, damage skin cells and trigger inflammation—causing redness, warmth, and pain.
Foreign bodies, such as splinters, activate a local immune response, leading to swelling and tenderness at the site.
From Chapter 1:
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