His heart has divided into four Chambers and its valves are beginning to form.
他的心脏已经分成了四个腔室，瓣膜也开始形成了。
2
Normally the sinoatrial node generates regular electrical pulses that spread across the Chambers of 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。
3
A human heart, by contrast, has four chambers. Two of these pump blood to the lungs, where it picks up oxygen, then the other two pump this oxygenated blood throughout the body.