Question

why does veins carry blood to the heart back?

Answer 1

Dear student,

Veins have thin walls and a large a lumen and causes less resistance to blood flow. Veins transport the blood from different organs back to the heart as these organs uses oxygen from the blood to perform various metabolic functions and then releases the used blood which contained waste product such as carbon dioxide into the veins. This impure blood is then transported to the heart from where it further returned to the lungs so that waste carbon dioxide is released and more oxygen is loaded by the blood.