What are the branches of the pulmonary arteries called that penetrate the lung tissue?

The branches of the pulmonary arteries that penetrate the lung tissue are known as arterioles. As pulmonary arteries carry deoxygenated blood from the heart to the lungs, they gradually divide into smaller vessels. The primary pulmonary arteries bifurcate into smaller arteries, which further branch into arterioles—these are the smaller diameter blood vessels that lead into the lungs' capillary networks.

Arterioles play a crucial role in regulating blood flow and pressure as they respond to different physiological conditions. They facilitate the transition from larger arteries to the microscopic capillary beds, where gas exchange occurs.

While capillaries are also involved in the blood flow within the lungs, they are the small vessels where oxygen and carbon dioxide exchange occurs, rather than the vessels that penetrate lung tissue. Venules are even larger vessels that collect blood from capillaries and direct it back towards the heart. Alveoli are the tiny air sacs within the lungs where gas exchange takes place, but they are not blood vessels. Thus, arterioles correctly describe the penetrating branches of the pulmonary arteries in lung tissue.