The lungs are unique organs in the body that have their own circulatory system. They are supplied with blood from the right half of the heart, rather than the left and the blood pressure in the arteries in the lungs is five times lower than in the rest of the body. That is necessary because the delicate alveoli in the lungs could not withstand the high blood pressure. The arteries of the lung consequently have much thinner walls, making them more fragile and meaning that surgical sutures can easily rip.
