Adrogué H E, Adrogué H J
Department of Medicine, University of Minnesota, Minneapolis, USA.
Respir Care. 2001 Apr;46(4):328-41.
Acid-base homeostasis involves chemical and physiologic processes responsible for the maintenance of the acidity of body fluids at levels that allow optimal function of the whole individual. The chemical processes represent the first line of defense to an acid or alkali load and include the extracellular and intracellular buffers, whereas the physiologic processes modulate acid-base composition by changes in cellular metabolism and by adaptive responses in the excretion of volatile acids by the lungs and fixed acids by the kidneys. The need for the existence of multiple mechanisms involved in acid-base regulation stems from the critical importance of the hydrogen ion (H+) concentration on the operation of many cellular enzymes and function of vital organs, most prominently the brain and the heart. The task imposed on the mechanisms that maintain acid-base homeostasis is large, since metabolic pathways are continuously consuming or producing H+, and the daily load of waste products for excretion in the form of volatile and fixed acids is substantial. We review the determinants of the acidity of body fluids, the mechanisms that maintain normal acid-base composition, and the overall defense to disruption in acid-base equilibrium. Specific topics include an examination of the scales of acidity, buffer systems, intracellular acid-base regulation, excretion of acids, alkali and acid loading, and normal acid-base composition. The limitations of arterial blood sampling in the assessment of acid-base status are also evaluated.
酸碱平衡涉及化学和生理过程，这些过程负责将体液酸度维持在能使个体整体功能达到最佳状态的水平。化学过程是抵御酸或碱负荷的第一道防线，包括细胞外和细胞内缓冲物质，而生理过程则通过细胞代谢的变化以及肺对挥发性酸和肾对固定酸排泄的适应性反应来调节酸碱组成。酸碱调节需要多种机制存在，这源于氢离子（H+）浓度对许多细胞酶的活性以及重要器官（最显著的是脑和心脏）功能的至关重要性。维持酸碱平衡的机制所面临的任务艰巨，因为代谢途径不断消耗或产生H+，而且以挥发性酸和固定酸形式排泄的每日废物负荷量很大。我们将回顾体液酸度的决定因素、维持正常酸碱组成的机制以及对酸碱平衡紊乱的整体防御。具体主题包括对酸度标度、缓冲系统、细胞内酸碱调节、酸的排泄、碱和酸负荷以及正常酸碱组成的研究。还将评估动脉血采样在评估酸碱状态方面的局限性。
