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举例说明急性中毒的机制。

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(1)局部化学损伤:强酸、强碱等腐蚀性化学物质可吸收组织中的水分,并与蛋白质或脂肪结合,使细胞变性、坏死,引起局部刺激、腐蚀或坏死。(2)缺氧:一氧化碳、硫化氢、氰化物等窒息性毒物可阻碍氧的吸收、转运或利用。脑和心肌对缺氧敏感,易发生损害。(3)抑制酶的活性:部分毒物由于其本身或代谢产物能够抑制酶的活性而产生毒性作用。如有机磷农药可抑制胆碱酯酶活性;重金属可抑制含巯基酶的活性,氰化物抑制细胞色素氧化酶的活性等。(4)中枢神经抑制作用:有机溶剂(如苯类)和吸入性麻醉剂(如乙醚)可通过血-脑脊液屏障作用于中枢神经系统,从而抑制脑功能。

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