The main pulmonary arteries emerge from the right side of the heart and then split into smaller arteries that progressively divide and become arterioles, eventually narrowing into the capillary microcirculation of the lungs where gas exchange occurs.

[citation needed] In order of blood flow, the pulmonary arteries start as the pulmonary trunk that leaves the fibrous pericardium (parietal pericardium) of the ventricular outflow tract of right ventricle (also known as infundibulum or conus arteriosus.

Above, the left main pulmonary artery is connected to the concavity of the proximal descending aorta by the ligamentum arteriosum.

[2] The right pulmonary artery pass across the midline of the body, below the carina of trachea, and comes in front of the right main bronchus.

As a septum develops between the two ventricles of the heart, two bulges form on either side of the truncus arteriosus.

During early development, the ductus arteriosus connects the pulmonary trunk and the aortic arch, allowing blood to bypass the lungs.

[11] The blood here passes through capillaries adjacent to alveoli and becomes oxygenated as part of the process of respiration.

The wedge pressure may be elevated in left heart failure,[13]: 190–191  mitral valve stenosis, and other conditions, such as sickle cell disease.

[13]: 720–721  Most recently, computational fluid based tools (non-invasive) have been proposed to be at par with the current clinical tests (invasive) of pulmonary hypertension.

Porcine model of pulmonary artery is the most frequently used and it was recently found that their mechanical properties vary with every subsequent branching.