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急性炎症I:炎症反応
急性炎症は、組織損傷や感染に対する急速かつ短命な生理学的反応であり、有害な物質を排除し修復を開始することを目的としています。この厳密に調整されたプロセスは通常数分から数日続き、微生物の侵入、物理的外傷、化学的損傷などの要因によって引き起こされます。
認識と仲介者解放
炎症反応は、肥満細胞、マクロファージ…
急性炎症は数分から数日続く短期的な反応で、感染、外傷、化学的損傷によって引き起こされ、壊死を引き起こします。
このプロセスは、体が有害な刺激を検出し、肥満細胞、マクロファージ、樹状細胞などの常駐免疫細胞を活性化することで始まります。これらの細胞はパターン認識受容体を通じて病原体関連および損傷関連の分子パターンを検出します。
活性化されると、これらの細胞はヒスタミンやプロスタグランジンなどの炎症性メディエーターを放出し、血管拡張や部位への血流増加を引き起こし、紅斑を引き起こします。
これらの血管の変化は、紅斑、浮腫、熱といった典型的な炎症の兆候を引き起こします。
プロスタグランジンやブラジキニンなどの腫れや炎症性メディエーターが局所神経を感作し、痛みを引き起こします。
TNFやIL-1などのサイトカインは内皮を活性化し、セレクチンや付着分子を発現させることで、白血球が影響を受けた部位に転がり、接着、ディアペデシーを行うことを可能にします。
白血球は病原体を排除し、破片も除去することで炎症を軽減し治癒を促進します。
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Q1: What triggers the acute inflammatory response in the body?
Acute inflammation is triggered by infection, trauma, or chemical injury that causes tissue damage. The body detects harmful stimuli through resident immune cells like mast cells, macrophages, and dendritic cells, which recognize pathogen-associated and damage-associated molecular patterns via pattern-recognition receptors. This recognition activates the inflammatory cascade.
Q2: How do inflammatory mediators cause the classic signs of inflammation?
Activated immune cells release inflammatory mediators such as histamine and prostaglandins, which cause vasodilation and increased blood flow to the injured site, producing erythema and heat. Simultaneously, increased vascular permeability allows fluid to move into surrounding tissue, causing edema. These mediators also sensitize local nerves, generating pain.
Q3: What role do cytokines play in leukocyte recruitment during inflammation?
Cytokines such as TNF and IL-1 activate the endothelium to express selectins and adhesion molecules on blood vessel walls. These molecules enable leukocytes to roll along the vessel surface, adhere firmly, and transmigrate through the endothelium into inflamed tissue via diapedesis, facilitating immune cell delivery to the injury site.
Q4: How long does acute inflammation typically last?
Acute inflammation is a short-term response that lasts from minutes to several days. This tightly regulated process is designed to eliminate harmful agents and initiate tissue repair. Once pathogens are cleared and debris is removed, the inflammatory response resolves and healing begins.
Q5: What functions do leukocytes perform once they reach inflamed tissue?
Leukocytes, particularly neutrophils, perform critical effector functions including phagocytosis of pathogens, release of antimicrobial enzymes, and clearance of necrotic debris. These actions eliminate harmful agents and remove damaged tissue, contributing to resolution of inflammation and promotion of tissue repair and healing.
Q6: How does vasodilation contribute to the inflammatory response?
Vasodilation of local arterioles increases blood flow to the injured area, delivering immune cells and nutrients while producing erythema and heat. Reduced flow velocity due to plasma leakage into tissue facilitates firm adhesion and transmigration of leukocytes across the endothelium, enabling immune cells to reach the inflammation site.
Q7: What happens after acute inflammation resolves?
Once leukocytes eliminate pathogens and clear debris, inflammation reduces and tissue repair is promoted. Understanding how acute inflammation progresses to local and systemic effects helps explain the transition from the acute phase to healing. Students can explore acute inflammation iii local and systemic effects for comprehensive coverage of inflammation's broader impact.