题目内容

（1）The pacemaker of the heart is the _________.

查看答案

搜索结果不匹配？点我反馈

更多问题

（2）The sac-like membrane surrounding of the heart is the ________.

（3）The wall of the heart between the right and the left atria is the _________.

（4）The relaxation phase of the heartbeat is called _________.

（5）Specialized conductive tissue in the wall between the ventricles is the ______.