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:
Some viruses are hard to treat because sometimes it’s not the virus that makes us sick; it’s our immune system.
Explanation:
<span>The muscle cell would have more mitochondria than the other types of animals cells.</span>
Members of eukarya have cells with nuclei, while members of eubacteria do not. May I have brainliest?❤️❤️❤️
Hope this helped!
