5.4
炎症反应I：血管和细胞
炎症反应是身体对细菌、创伤、毒素或热引起的感染、损伤或刺激的一种防御机制。炎症有助于定位和摧毁病原体，并清除受损组织成分，以促进身体修复。在验证的初始阶段，液体、血液产品和营养物质会向受伤区域汇聚，导致出现发红、热、肿胀、疼痛和功能障碍。此外，全身性炎症的表现包括发热、白细胞计数上升、不适、食欲不振…
炎症反应是机体针对感染、损伤或刺激的一种防御机制。
它可以是急性的，持续数天或数周，也可以是慢性的，持续数月到数年。
炎症有助于识别和清除病原体，并去除受损的组织成分，从而使机体得以修复。
这种反应在血管水平和细胞水平均可观察到。两者均为急性炎症过程的关键组成部分。
在血管阶段，损伤部位附近的微小血管最初会收缩，以防止失血。
供应该区域的动脉和静脉扩张，增加血流量，导致局部发红和发热。
此外，损伤区域释放的细胞介质（如组胺、缓激肽和前列腺素）会增加血管通透性，使富含蛋白质和免疫细胞的液体渗出，从而导致肿胀、疼痛和功能丧失。
在细胞阶段，白细胞（WBC）会穿过血管并迅速到达损伤部位，导致白细胞总数升高。
白细胞（如中性粒细胞和单核细胞）可吞噬病原体并摄取细胞碎片及外来物质。由于病原体被吞噬后会释放致热原，从而引起发热。
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Q1: What is the inflammatory response and why does the body trigger it?
The inflammatory response is a defense mechanism against infection, injury, or irritation from bacteria, trauma, toxins, or heat. It helps locate and destroy pathogens while removing damaged tissue elements to promote healing. This response occurs at both vascular and cellular levels, with fluid, blood products, and nutrients migrating to the injured area, resulting in redness, heat, swelling, pain, and loss of function.
Q2: What happens to blood vessels during the vascular stage of inflammation?
During the vascular stage, small blood vessels near the injury site initially constrict to prevent blood loss. The arterioles and venules then dilate, increasing blood flow and causing local redness and heat. Cell mediators like histamine and bradykinin are released, increasing vascular permeability and allowing protein-rich fluids to flow into the area, causing swelling and pain.
Q3: How do white blood cells respond during the cellular stage of inflammation?
During the cellular stage, white blood cells, including neutrophils and monocytes, pass through blood vessels and rush to the injury site, increasing overall WBC count. These cells engulf pathogens through phagocytosis and ingest cell debris and foreign material. This phagocytic activity releases pyrogens from bacterial cells, which trigger fever as part of the systemic inflammatory response.
Q4: What role do cell mediators play in the inflammatory response?
Cell mediators such as histamine, bradykinin, and prostaglandins are released in the injured area during inflammation. These mediators increase vascular permeability, allowing protein- and immune-cell-rich fluids to escape blood vessels and enter surrounding tissue. This fluid accumulation causes the characteristic swelling, pain, and temporary loss of function associated with acute inflammation.
Q5: How long can inflammation last and what are the different types?
Inflammation can be acute, lasting days or weeks, or chronic, lasting several months to years. Acute inflammation is the initial response to injury or infection, characterized by vascular and cellular changes. Chronic inflammation represents a prolonged response when the body cannot fully resolve the initial insult, potentially leading to tissue damage and systemic complications.
Q6: What systemic signs indicate that inflammation is occurring throughout the body?
Systemic inflammation produces signs beyond the local injury site, including fever, increased white blood cell count, malaise, anorexia, nausea, and vomiting. Lymph node enlargement may also occur as lymphoid tissues respond to infection. In severe cases, organ failure can develop, indicating that the inflammatory response has become widespread and potentially harmful.
Q7: Why does fever develop as part of the inflammatory response?
Fever develops when white blood cells engulf pathogens through phagocytosis during the cellular stage of inflammation. This phagocytic activity releases pyrogens from bacterial cells, which are fever-inducing substances. Pyrogens circulate through the bloodstream and act on the body's temperature-regulating center, raising the set point and causing fever as part of the systemic inflammatory defense.