PHYSIOLOGY OF THE CIRCADIAN TIMING SYSTEM - PREDICTIVE VERSUS REACTIVE HOMEOSTASIS
PHYSIOLOGY OF THE CIRCADIAN TIMING SYSTEM - PREDICTIVE VERSUS REACTIVE HOMEOSTASIS
复制标题
DOI：
10.1152/ajpregu.1986.250.5.r737
复制
发表时间：
1986-05-01
影响因子：
--
通讯作者：
MOOREEDE, MC
中科院分区：
文献类型：
--
作者：
MOOREEDE, MC
自60年前Cannon首次提出内稳态的概念以来，人们的注意力一直集中在生物体稳态受到干扰后启动的纠正反应上。在这个讲座中，有人认为，稳态的概念应该扩展到包括昼夜（和circannual）定时系统的精确定时机制，使生物体能够预测环境挑战何时最有可能发生。对内稳态的成熟理解应该包括对已经发生的生理变量变化的“反应性”反应和在预期可预测的定时挑战中发起的“预测性”反应。这种预测性反应具有特别的价值，因为它们能够通过在可能的挑战之前的适当时间激活生理机制来立即利用生理机制，即使它们涉及几个小时的延迟。然而，预测和现实之间往往会发生冲突。睡眠-觉醒行为、体温调节、血容量稳态和钾平衡调节的例子表明，预测性反应往往会损害反应性稳态机制的有效性，甚至危及生物体的生存。必须得出的结论是，自然环境的昼夜循环在塑造自我平衡机制的进化发展中发挥了重要作用，因为光照，温度，食物供应和捕食者活动的昼夜变化具有主导性的可预测性。
Since Cannon first formulated the concept of homeostasis 60 years ago, attention has been focused on the corrective responses initiated after the steady state of the organism is perturbed. In this lecture it is argued that the concept of homeostasis should be extended to include the precisely timed mechanisms of the circadian (and circannual) timing system which enables organisms to predict when environmental challenges are most likely to occur. A mature understanding of homeostasis should encompass both "reactive" responses to changes in physiological variables which have already occurred and the "predictive" responses initiated in anticipation of predictably timed challenges. Such predictive responses have particular value because they enable physiological mechanisms to be utilized immediately, even if they involve a delay of several hours, by activating them at a suitable time in advance of a probable challenge. However, conflicts may often occur between predictions and reality. Examples from sleep-wake behavior, thermoregulation, blood volume homeostasis, and the regulation of potassium balance show that predictive responses often compromise the effectiveness of reactive homeostatic mechanisms even to the point of risking the survival of the organism. It must be concluded that the day-night cycle of the natural environment has played a fundamental role in shaping the evolutionary development of homeostatic mechanisms because of the dominating predictability of diurnal changes in illumination, temperature, food availability, and predator activity.