The Cardiopulmonary Circuit: How Your Heart and Lungs Work Together, Explained by Dr. Mikell Jarratt, Pulmonologist
Have you ever wondered what is really happening with every heartbeat and every breath? It is easy to forget that a natural process, occurring effortlessly, is a complex system involving multiple organs critical to sustaining life.
Your heart and lungs aren't working independently. They are collaborating in a lifelong partnership called the cardiopulmonary circuit. Dr. Mikell Jarratt, board-certified pulmonologist with CaroMont Pulmonary Medicine, wants to explain the incredible process happening beneath the surface and help you understand how to keep it functioning well.
Here's what you need to know about the cardiopulmonary circuit:
What Is the Cardiopulmonary Circuit?
The cardiopulmonary circuit is the pathway that blood takes from your heart to your lungs and back again. This system is responsible for one of your body's most critical tasks, which is getting oxygen where it needs to go and removing the waste your cells produce.
“It’s not just about your lungs and your heart,” explains Dr. Jarratt. “The cardiopulmonary system is essentially the engine that keeps everything else running, working in a seamless loop to deliver oxygen to every cell in your body and remove waste products like carbon dioxide. Taking care of this system isn't just about your heart or your lungs in isolation. Instead, think about it as protecting the foundation that every other organ in the human body depends on.”
From Your Heart to Your Lungs
Your heart and lungs work together from your very first breath to your last. When the blood returns to your heart from the rest of your body, it is depleted of its oxygen supply and full of carbon dioxide waste. This deoxygenated blood enters the right atrium of the heart, passes through the right ventricle, and is then pumped through the pulmonary artery to both lungs.
“Your heart is beating, moving deoxygenated blood to the lungs, and at the same time you are breathing in and out,” explains Dr. Jarratt. “It's a continuous, simultaneous exchange happening millions of times a day without you ever thinking about it.”
Gas Exchange in the Lungs
As your blood circulates through your lungs, and it reaches tiny air sacs called alveoli, where gas exchange takes place. On average, humans have about 300 million alveoli, giving a total surface area roughly comparable to a tennis court.
“The alveoli walls are incredibly thin and surrounded by tiny capillaries,” explains Dr. Jarratt. “This is where oxygen from the air you breathe passes into your blood. At the same time, carbon dioxide moves from your blood into the alveoli to be exhaled. All of this is achieved by simple diffusion, as gases move from an area of high to low concentration.”
The Return
Oxygen-rich blood then returns to the heart through the pulmonary veins into the left atrium and then into the left ventricle. Oxygenated blood is then pumped out through the aorta to supply oxygen to your whole body.
The Numbers Behind the System
Your total blood volume, which is about five liters (about 1.3 gallons), makes this cycle occur approximately once every minute while you are resting. If you are exercising, your heart can pump up to 25 liters of blood per minute. Every day, you take about 20,000 breaths and your heart beats an average of 100,000 times. Your lungs will transfer about 250 milliliters of oxygen into your blood per minute while you are resting.
When Health Challenges Arise
Because the cardiopulmonary circuit is so critical in sustaining life, disruptions to the system or conditions that cause it to not function properly can cause significant health concerns.
Serious, but manageable conditions, can include:
Chronic obstructive pulmonary disease (COPD)
Asthma
Chronic bronchitis
Emphysema
Pulmonary hypertension
Chronic/stable heart failure
Sleep apnea
Atrial fibrillation
Coronary artery disease
Immediately life-threatening conditions can include:
Pulmonary embolism
Heart attack (myocardial infarction)
Cardiac arrest
Acute respiratory failure
Aortic dissection
Tension pneumothorax
“When problems do arise with this system, they should be taken very seriously,” says Dr. Jarratt. “These conditions can cause a variety of symptoms like shortness of breath, chest discomfort, fast or irregular heartbeat, persistent cough and unusual fatigue or dizziness. If you are noticing these changes, you need to seek medical treatment.”
Proactive Care, Critical to Your Health
Taking care of your lungs and heart is extremely critical to wellbeing, as these organs work together to keep your body healthy and functioning. Dr. Jarratt recommends these simple, everyday lifestyle choices to support a healthy cardiopulmonary circuit:
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Exercise: Regular exercise like walking, swimming or activities you enjoy will improve the strength of your heart and lungs. Aim for 30 minutes of moderate cardiovascular exercise five times a week. If you are considering a new exercise program, it is important to consult with your healthcare provider, especially if you have health conditions like the ones mentioned above.
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Stop Smoking: If you are a smoker, consider quitting. Smoking destroys the alveoli in your lungs which are critical to the exchange of oxygen in the bloodstream. Additionally, smoking attacks both the pulmonary and cardiac systems simultaneously, compounding health issues when the heart has to work harder to compensate for lungs that are less efficient. Talk to your doctor about resources to help you quit.
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Healthy Diet: A diet consisting of whole foods that are rich in antioxidants, omega-3 fatty acids and a variety of nutrients can support lung and heart health. For personalized dietary advice, ask your healthcare provider about scheduling an appointment with a registered dietitian.
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Track Your Blood Pressure: Regular blood pressure readings can help keep you aware of what is often referred to as the 'silent killer.' If blood pressure is high or out of normal limits, it is important to work with your primary care provider to get it under control through medication or lifestyle changes.
When your lungs are healthy, everything works better. Strong lungs keep oxygen moving freely and efficiently through your body, powering everything from your heartbeat to your thoughts. Taking care of your lungs today means a healthier and more vibrant life tomorrow.
“The cardiopulmonary system is one of the hardest working systems in the human body,” says Dr. Jarratt. “It never stops, never rests, and asks very little in return. But like anything that works that hard, it deserves to be looked after. Give it regular movement and a healthy lifestyle, and it will serve you well for decades to come.”