Final answer:
Vessels such as the pulmonary arteries and veins form the pulmonary circulation that carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation and returns the oxygen-rich blood to the left atrium. The pulmonary arteries are unique as they carry deoxygenated blood, while the pulmonary veins carry oxygen-rich blood, which is opposite to their typical functions in the systemic circulation.
Step-by-step explanation:
Vessels account for pulmonary blood flow through a specific circuit known as the pulmonary circulation. This circuit is responsible for gas exchange, as it directs blood low in oxygen from the right side of the heart to the lungs and returns oxygen-rich blood to the left side of the heart. Initially, deoxygentated blood exits the right ventricle into the pulmonary trunk, which splits into the left and right pulmonary arteries. These arteries further branch out within the lungs, leading to the pulmonary capillaries near the alveoli where the crucial gas exchange takes place, replenishing the blood with oxygen and ridding it of carbon dioxide.
Once oxygenated, the blood returns to the heart through the pulmonary veins, the only veins in the post-natal body that carry highly oxygenated blood. This replenished blood is delivered into the left atrium and subsequently into the left ventricle, from which it is pumped into the aorta and through the systemic circuit to provide oxygen and nutrients to the body's tissues. Therefore, the pulmonary arteries and veins are vital vessels that account for the lung's role in receiving deoxygenated blood from the body and sending oxygenated blood back into the body's systemic circulation.