鸡鸣晨起,日落而歇。人类的生理节奏与外界的周期变化,特别是昼夜周期是同步的。因此生理学家相信人体内有一个“生物钟”在控制每个人生理活动的时间节奏。这个钟当然不是石英钟,更不是机械钟,应该是某一个生物组织。它在哪里呢?最近,美国哈佛大学、塔夫茨大学和马萨诸塞州医院的三位科学家在解剖了新鲜人脑组织后证实,视交叉上核是体内唯一的生物钟结构组织,从而确定了生物钟的确切位置。 那么生物钟的“发条”在哪儿呢?现在科学家一致公认,重量仅0.1～0.2克、藏在大脑两叶间深处的松果体是生物钟的直接操纵者。松果你是通过分泌一种叫“褪黑色素”的激素来控制生物钟活动的。黑暗时,褪黑色素分泌增加;而光亮会抑制褪黑色素的分泌。通过这种亮暗周期有规律的变化,褪黑色素就向中枢神经系统,特别是视交叉上核发出调节时间的信号,再由视交叉上核决定何时使人睡眠,何时使 Early morning cock, sunset and rest. Human circadian rhythms and the cyclical changes in the outside world, especially the circadian cycle are synchronized. Physiologists therefore believe that there is a “circadian clock” in the human body that controls the rhythm of each person’s physical activity. This clock, of course, is not a quartz clock, not a mechanical clock, it should be a biological organization. Where is it? Recently, three scientists from Harvard University, Tufts University and the Massachusetts State Hospital, after dissecting fresh human brain tissue, confirmed that the suprachiasmatic nucleus is the only biological clock structure in the body that identifies the biological clock Exact location So where is the clockwork clock? Now scientists unanimously recognized that the weight of only 0.1 to 0.2 grams, hidden in the deep brain of the pineal gland is the direct manipulator of the biological clock. You control the clock movement by secreting a hormone called melatonin. Dark, melatonin secretion increased; and light will inhibit melatonin secretion. Through the regular changes of bright and dark cycles, melatonin signals to the central nervous system, especially the suprachiasmatic nucleus, the timing of the regulation, and the suprachiasmatic nucleus decides when to sleep and when