Breathing and exchange of gases
Ans is 3 explain please
Pulmonary vein carries blood from lungs so it has maximum oxygen i.e X
Then from lungs systematic artery carries to different parts of body
Systematic vein bring blood from different parts of body which has less partial pressure of oxygen i.e Y
PaO2 – Partial pressure of oxygen at sea level (160 mmHg in the atmosphere) in arterial blood is between 75 mmHg and 100 mmHg. PvO2 – Oxygen tension in venous blood at sea level is between 30 mmHg and 40 mmHg.
During exercise there is more oxygen required i.e least partial pressure of oxygen in blood.