The heart and lungs work closely together to ensure that oxygen is delivered to the entire body and carbon dioxide is removed efficiently. Here is how they cooperate:
- Oxygen-depleted blood from the body enters the right side of the heart (right atrium and right ventricle). The heart then pumps this blood to the lungs via the pulmonary artery
- In the lungs, blood passes through tiny air sacs called alveoli, where carbon dioxide is exchanged for oxygen during breathing. Oxygen enters the blood, and carbon dioxide is expelled when you exhale
- Oxygen-rich blood returns from the lungs to the left side of the heart (left atrium and left ventricle) through the pulmonary veins
- The left side of the heart then pumps the oxygenated blood through the aorta and arteries to all the body's organs, tissues, and cells, supplying them with the oxygen they need to function
- After delivering oxygen, the blood becomes oxygen-poor again and returns to the right side of the heart to repeat the cycle
This continuous loop of blood flow between the heart and lungs is called the pulmonary circuit, and it works in tandem with the systemic circuit that delivers oxygenated blood throughout the body
. Additionally, the heart and lungs interact mechanically and neurologically to optimize oxygen delivery and blood flow. Breathing affects pressures in the chest that influence heart function, and the cardiovascular and respiratory systems have rhythmical oscillators that couple to regulate heart rate and breathing efficiently
. In summary, the lungs oxygenate the blood, and the heart pumps this oxygen- rich blood to the body, while also returning oxygen-poor blood to the lungs for reoxygenation. This partnership is vital for sustaining life and meeting the body's oxygen demands, especially during activities like exercise when oxygen needs increase
