Normally the sinoatrial node generates regular electrical pulses that spread across the Chambersof the heart, causing the cells to contract in synchrony.
正常情况下，窦房结产生规律的电脉冲，传入各心房，再带动细胞同步收缩。
2
At the heartof the fire, temperatures easily exceeded 1,000 degrees [Fahrenheit]. Lethal clouds of carbon monoxide and other gases swirled through the rock Chambers.
在大火中心，温度超过1000度，由一氧化碳和其它毒气形成的致命云团裹住了人们的房子。
3
When the heart beats, an electrical signal passes from the top of the heart, near the atria (upper chambers), down through the ventricles (lower chambers), and the chambers contract in that order.