Great Vessels of the Heart
What are the great vessels of the heart?
The great vessels of the heart are major blood vessels that connect directly to your heart. These arteries and veins circulate blood between your heart and lungs, and between your heart and the rest of your body.
The great vessels include your:
- Main pulmonary artery (also called your pulmonary trunk).
- Pulmonary veins.
- Superior vena cava.
- Inferior vena cava.
Your great vessels work as a system of highways to keep blood moving in the correct paths throughout your body. These vessels connect with various chambers of your heart to send blood in and out of your heart in a coordinated fashion each time your heart beats.
Your aorta and pulmonary trunk (arteries) send blood out of your heart. Your pulmonary veins, superior vena cava and inferior vena cava (veins) carry blood into your heart.
What is the function of the great vessels of the heart?
Your great vessels are a vital part of your circulatory system. There are two main circulatory system circuits: the pulmonary circuit and the systemic circuit. Here’s a breakdown of what those circuits do and the role your great vessels play.
|Circuit||The circuit’s job||The role of your great vessels|
|Pulmonary circuit.||Sends blood between your heart and lungs. First, oxygen-poor blood travels from your heart to your lungs. There, it receives oxygen and gets rid of waste. This refreshed blood then travels back to your heart.|
• Main pulmonary artery: Carries oxygen-poor blood from your heart’s right ventricle into your left and right pulmonary arteries. These arteries carry the blood to your lungs.
• Pulmonary veins: Carry oxygen-rich blood from your lungs to your heart. All of your pulmonary veins (usually four) directly empty into your heart’s left atrium.
|Systemic circuit.||Sends blood between your heart and the rest of your body. First, oxygen-rich blood leaves your heart. It circulates throughout your body, where it delivers oxygen, nutrients and hormones to your organs and tissues. It also picks up waste. This blood, now low on oxygen and containing waste products, travels back to your heart.|
• Aorta: The first part of your aorta, called your ascending aorta, carries oxygen-rich blood directly out of your heart’s left ventricle. From there, blood flows into your aorta’s many branches to nourish the rest of your body.
• Superior vena cava: This large vein delivers oxygen-poor blood from your upper body into your heart’s right atrium.
• Inferior vena cava: This large vein delivers oxygen-poor blood from your lower body into your heart’s right atrium.
Normally, arteries contain oxygen-rich blood, and veins contain oxygen-poor blood. However, there are two exceptions to this rule: your pulmonary arteries carry oxygen-poor blood, and your pulmonary veins carry oxygen-rich blood.
Where are the great vessels of the heart located?
The great vessels of the heart connect to your heart’s chambers. The chart below shows where each vessel connects and the direction of blood flow.
|Great vessel||Where it connects to your heart||Direction of blood flow|
|Aorta.||Left ventricle (via your aortic valve).||Heart to artery.|
|Main pulmonary artery.||Right ventricle (via your pulmonary valve).||Heart to artery.|
|Pulmonary veins.||Left atrium.||Vein to heart.|
|Superior vena cava.||Right atrium.||Vein to heart.|
|Inferior vena cava.||Right atrium.||Vein to heart.|
Most people have four pulmonary veins. They each drain blood from a different section of your lungs and carry it to your heart. They’re called:
- Right superior pulmonary vein.
- Right inferior pulmonary vein.
- Left superior pulmonary vein.
- Left inferior pulmonary vein.
What are the great vessels made of?
Three layers of tissue make up the walls of your great vessels:
- Tunica intima: This is the inner layer that directly comes into contact with your blood. It’s lined with endothelial cells that help your blood flow smoothly.
- Tunica media: This is the middle layer. It’s made of elastic fibers that help your blood flow in the proper direction. This layer also helps your blood vessels contract and relax. Healthcare providers call these processes vasoconstriction and vasodilation.
- Tunica adventitia: This is the outer layer that provides structure to your vessels.
Like your other blood vessels, your great vessels have a tube-like shape. The walls surround and protect the lumen, or the opening through which your blood flows.
How big are they?
The great vessels of your heart have a wider lumen (opening) compared with your other arteries and veins. They need to be wider to accommodate the heavy volume of blood flow. Your aorta and pulmonary artery must also withstand forceful pressure from your heart’s pumping action.
The diameter (width of the lumen) varies based on many factors like your age and sex assigned at birth. Plus, different imaging methods establish different diameters in published research. The estimates below give you a general idea of the diameter of your great vessels:
- Ascending aorta: 2.1 centimeters (cm).
- Superior vena cava: 2.0 cm.
- Inferior vena cava: 2.2 cm.
- Main pulmonary artery: 2.7 cm (people assigned female at birth); 2.9 cm (people assigned male at birth).
- Right superior pulmonary vein: 1.5 cm to 1.9 cm.
- Right inferior pulmonary vein: 1.3 cm to 1.8 cm.
- Left superior pulmonary vein: 1.4 cm to 1.9 cm.
- Left inferior pulmonary vein: 1.3 cm to 1.6 cm.
Conditions and Disorders
What conditions and disorders affect the great vessels?
Many conditions can affect your great vessels. These include congenital heart diseases (present at birth) as well as conditions you develop later in life. The chart below lists some conditions that can affect each great vessel.
|Aorta||Pulmonary artery||Pulmonary veins||Superior and inferior vena cava|
• Tetralogy of Fallot.
• Transposition of the great arteries.
• Patent ductus arteriosus.
• Partial anomalous pulmonary venous return (PAPVR).
• Pulmonary vein obstruction (usually due to a tumor).
• Pulmonary vein stenosis.
• Pulmonary venous hypertension.
• Blood clots (pulmonary vein thrombosis).
• Inferior vena cava syndrome.
• Blood clots.
How can I keep my great vessels healthy?
A heart-healthy lifestyle can help you keep your great vessels and all your blood vessels healthy. Tips include:
- Don’t smoke, vape or use any tobacco products. Talk to your provider about strategies to help you quit.
- Eat a heart-healthy diet. This includes limiting your intake of salt, sugar and saturated fat. It also means adding more soluble fiber, whole grains, fruits and veggies to your meals.
- Exercise regularly. Talk to your provider about a routine that’s safe for you.
- Limit alcohol, or avoid it altogether.
- Manage conditions like high blood pressure and high cholesterol. This may involve taking medications.
- Visit a healthcare provider each year for a checkup.
A note from Cleveland Clinic
The great vessels of the heart are truly “great.” They play a major role in sending blood to and from your heart and supporting the daily work of your circulatory system. Your great vessels allow all your other blood vessels to do their jobs and supply your body with oxygen as well as remove waste.
Learning your great vessel anatomy can help you picture what’s going on inside your body with each heartbeat. Talk to your healthcare provider if you have questions or concerns about your blood vessels or what you can do to keep them healthy.
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