Blood pressure in the arteries is much higher than in the veins, in part due to receiving blood from the heart after contraction, but also due to their contractile capacity. So blood pressure in the pulmonary artery more than that in the pulmonary vein and venae cava. Blood pressure in the pulmonary circulation is lower than in the systemic circulation. The walls of the pulmonary capillaries are thinner than those of similar vessels in the systemic circulation. The low vascular resistance in the pulmonary circulation relies on remarkably thin vascular walls. Aorta and carotid arteries are a part of the systemic circulation and the blood pressure in them is higher than the pulmonary artery.

──────────────────────────────────────────────────────────────────────────────────────────