The pulmonary artery is a major blood vessel that carries deoxygenated blood from the heart to the lungs. It originates from the right ventricle of the heart and splits into two branches, one for each lung. This process is essential for oxygenating the blood, allowing it to pick up oxygen and release carbon dioxide. Once the blood reaches the lungs, it travels through smaller vessels called pulmonary arterioles and eventually into the capillaries surrounding the alveoli, where gas exchange occurs. After this, the now oxygen-rich blood returns to the heart through the pulmonary veins.