Question

How origin of heartbeat takes place in human heart? Name the group of animals with

double circulation. How is it important​

Answer 1

Answer:

The human circulatory system has three key components: blood vessels, blood and the heart. It is called a double circulatory system because blood passes through the heart twice per circuit. The right pump sends deoxygenated blood to the lungs where it becomes oxygenated and returns back to the heart.