- 期刊
- OpenAccess
Cardiovascular Responses to Breath-Hold Diving in Mammals
哺乳動物潛水時之心血管反應
摘要
潛水對於哺乳動物而言是一項嚴厲的挑戰。閉氣時，因為氧氣來源斷絕及二氧化碳迅速堆積，體內環境急劇變化。動物為了因應這挑戰，衍生出特別的生理調適機轉，以維持體內環境的恆定。雖然潛水哺乳動物體內具備有較高的氧氣儲存量，足以應付短時間的閉氣，若要維持長時間的潛水，則需要降低身體之耗氧量。這機制稱之為潛水反射，包括心跳減緩、心輸出量降低、血管阻力增加、以及血流在分佈等。主要作用是減少非活躍器官的血流量及供氧量，以供應氧氣依賴性高的器官之所需。潛水反射是受神經系統調控的生理機制。閉氣潛水時交感及副交感神經都是處於興奮狀態。至於中樞神經系統如何整合呼吸中樞及主掌心跳血壓的心血管中樞，則尚待研究。
並列摘要
To mammals, diving is a deep stress that causes a tremendous disturbance in its internal environment. Physiological adjustments occur during breath-hold diving in order to overcome this stress and hence to maintain a homeostasis. Although diving mammals have higher oxygen storage, reduced oxygen consumption during breath-hold enables them to dive longer. The cardiovascular responses reduce the blood flow and hence the oxygen consumption to the non-critical organs and maintain an adequate oxygen supply to the brain. Simultaneous activation of the sympathetic and parasympathetic nervous systems reduces the heart rate and hence the cardiac output and increases vascular resistance in the non-critical organs. The central integration of the autonomic responses remains to be investigated.