Question

why is thedeoxygenateed blood passed through the heart then flows to the lungs

cant it diirectly flow to the lungs ??

what is the role of the deoxygenated blood flowing through the heart ?

Answer 1

The deoxygenated blood is collected from the upper and lower body through superior and inferior vena cava respectively and enters the heart. It is then pumped at the required pressure and passed to lungs for oxygenation through pulmonary artery. The heart here does two functions- collects the deoxygenated blood and pump it collectively to the lungs at the required pressure. So, it does not reach the lungs directly.

The deoxygenated blood flows through the heart in order to get oxygenated through double circulation.