Question

The oxygenated blood from the lungs is brought to the heart by which of the following vascular systems?
A. Pulmonary artery
B. Pulmonary veins
C. Aorta
D. Capillaries

Answer 1

Hint:-
A mammalian heart is a muscular pump and has four chambers. Its highly efficient muscles rhythmically contract and relax constantly to supply the body with blood. The heart functions in conjunction with the lungs i.e. the respiratory system.

Complete step-by-step solution:- Heart and lungs are connected with each other through the pulmonary artery and veins. The heart follows the mechanism of double circulation for the flow of blood i.e. the blood enters the heart twice before being circulated in the body.
Double circulation involves two pathways i.e. systemic circulation and pulmonary circulation.
- In the systemic circulation, the blood carrying oxygen from the left ventricle is pumped into the systemic arch which delivers the blood to all parts of the body except the lungs. Oxygen from the blood is used up by different organs and deoxygenated blood is carried back from different parts of the body by veins to the superior vena cava and inferior vena cava which empty themselves into the right auricle.
- In pulmonary circulation, the oxygen-deficient blood in the right auricle is pushed into the right ventricle which in turn sends it to the lungs with the help of the pulmonary artery for oxygenation. After purification, the blood is collected by venules that unite to form veins. The oxygenated blood is carried back to the left auricle by four pulmonary veins. The right auricle now pumps the oxygenated blood into the left ventricle.
So, the correct answer is (B), Pulmonary veins.

Additional information:
Pulmonary arteries are the only arteries that carry deoxygenated or impure blood in the body whereas, pulmonary veins are the only veins that carry oxygen-rich blood in the body.

Note:- Double circulation is an efficient mechanism that strictly separates both oxygenated and deoxygenated blood from mixing. It ensures that a dedicated supply of oxygen is maintained in the body thereby, improving its efficiency.