Related Clues:

• It's close to your heart
• Chest contents
• Air bags?
• Fish's lack
• Breathing organ
• It's found in a chest
• Bronchus outlet
• Air bag, of a sort
• Pulmonary organ
• They're close to your heart
• Where inhaled air goes
• Aqua-___
• Subjects of pneumography
• Breathing need
• Breathing apparatus?