Inhaling through the nose
Since the other answer got deleted, i'll just answer it for you.
a sinoatrial node is the main pacemaker that begins each heartbeat located in the junctions of superior vena cava and the right atrium. It signals from the node that spread through the atria and determines the heart rates.
Answer:
D i belive, if i'm worng, please don't be mean about it
Explanation:
1 is four
2 is protozoan
3 is museums
4 is fungi
5 is only one kingdom
6 is protozoan 7 is 2
