The Blood Supply to the Lungs

• • The lungs receive blood from two sources: the pulmonary circuit and the bronchial arteries of the systemic circuit
• Respiratory exchange surfaces receive blood from arteries of pulmonary circuit
• In addition to providing for gas exchange, the endothelial cells of the alveolar capillaries are the primary source of angiotensin-converting enzyme (ACE), which converts circulating angiotensin I to angiotensin II