Question

In the pulmonary artery blood flows from the heart to the lungs and in the pulmonary vein blood returns from the lungs to the heart. The blood in the pulmonary artery is

• A. Higher in $O_2$ and lower in ${CO}_2$ content than the blood in the pulmonary vein
• B. Higher in both $O_2$ and ${CO}_2$ content than the blood in the pulmonary vein
• C. Lower in $O_2$ and higher in ${CO}_2$ content than the blood in the pulmonary vein
• D. Lower in both $O_2$ and ${CO}_2$ content than the blood in the pulmonary vein
• E. Higher in $O_2$ content, but about the same in ${CO}_2$ content as the blood in the pulmonary vein

Answer 1

Answer: (C)

Lower in $O_2$ and higher in ${CO}_2$ content than the blood in the pulmonary vein

The left ventricle pumps blood into the aorta which in turn branches and delivers blood to the major body regions and organs. The anterior vena cava collects deoxygenated blood from the head, chest and arms and enters the right atrium while the inferior vena cava collects blood from the lower body regions. Both venae cavae pass the deoxygenated blood to the right atrium. Blood from right atrium enters right ventral and pulmonary arteries carry deoxygenated blood from right ventricle to lungs for oxygenation. Two pulmonary veins come from each lung and pass O${}_2$ rich blood to left atrium. Thus blood in pulmonary arteries is oxygen deficient but rich in carbon dioxide as compared to that of pulmonary veins.