What is the role of blood flow through the heart?

Your heart is a powerful muscle, about the size of your fist. Every second, it pumps nutrient- and oxygen-rich blood to your body. With each heartbeat, your heart sends blood through your circulatory system.

Blood is crucial to remain alive. Blood carries oxygen and nutrients from your heart to other tissues throughout your body. It also carries waste products such as carbon dioxide away from your tissues.

What is the circulatory system?

Your circulatory system is a network of blood vessels. Blood vessels are small tubes that carry blood all over your body. Blood flows through three types of blood vessels:

  • Arteries carry oxygen-rich blood away from your heart.
  • Capillaries are tiny, thin blood vessels that connect veins and arteries.
  • Veins carry oxygen-poor blood from your body’s tissues back to your heart.

Where does blood flow through the heart?

Your heart itself is made of muscle nourished by blood vessels. Your heart has four chambers. The chambers are like rooms in the “house” of your heart. If you look at a diagram of a heart, these chambers divide into upper and lower chambers and left and right chambers.

  • Atria are your two upper heart chambers. You have a left atrium and a right atrium.
  • Ventricles are your two lower heart chambers. You have a left ventricle and a right ventricle.

Between the top and bottom chambers, you have heart valves. Heart valves open and close to allow for proper blood flow. Your valves ensure that blood flows only in one direction. These valves are:

  • Aortic valve connects your left ventricle and aorta (large artery that carries blood throughout your body).
  • Mitral valve connects your left atrium and left ventricle.
  • Pulmonary valve connects your right ventricle and pulmonary arteries (arteries that carry blood to your lungs).
  • Tricuspid valve connects your right atrium and right ventricle.

What is the order of blood flow through the heart, step by step?

The right and left sides of your heart work together to ensure blood flows throughout your whole body. Blood flows through your heart through a series of steps. These steps take place in the space of one heartbeat — just a second or two.

On the right side

  1. Oxygen-poor blood from all over your body enters your right atrium through two large veins, your inferior vena cava and superior vena cava.
  2. Your tricuspid valve opens to let blood travel from your right atrium to your right ventricle.
  3. When your right ventricle is full it squeezes, which closes your tricuspid valve and opens your pulmonary valve.
  4. Blood flows through your pulmonary artery to your lungs, where it gets oxygen.

On the left side

  1. Oxygen-rich blood travels from your lungs to your left atrium through large veins called pulmonary veins.
  2. Your mitral valve opens to send blood from your left atrium to your left ventricle.
  3. When your left ventricle is full it squeezes, which closes your mitral valve and opens your aortic valve.
  4. Your heart sends blood through your aortic valve to your aorta, where it flows to the rest of your body.

What signals control your heartbeat?

Your heart contracts (beats) when it receives an electrical impulse from your sinoatrial (SA) node. This signal is called heart conduction. The SA node is your body’s “natural pacemaker,” setting your heart’s rhythm.

Heart conduction continues as the electrical signal moves to the atrioventricular (AV) node in your right atria. The signal then travels down the His-Purkinje system (a bundle of special fibers) and spreads to the rest of your heart.

How fast or slow your heart beats varies throughout the day. Your nervous system sends electrical signals and your endocrine system sends hormones that control your heart rate. These signals help your heart adapt to your body’s changing needs. For example, your heartbeat quickens when you run and slows when you sleep.

How much blood does your heart pump?

Your heart pumps about 2,000 gallons of blood each day. That’s enough to fill an 8-by-10-foot swimming pool!

It beats around 100,000 times daily. In an average life span of almost 79 years, your heart beats nearly 2.9 billion times.

What conditions or disorders affect your heart’s blood flow?

Some conditions can affect the pathway of blood flow in your heart. Some of these conditions include:

How can I improve my heart health?

You can take some steps to live a healthier lifestyle and improve your cardiovascular health. You may:

A note from Cleveland Clinic

Every day, blood pumps throughout your heart and the rest of your body. The process of blood flowing through your heart is crucial for staying alive and healthy. When blood enters your heart, it is low in oxygen. Your heart sends the blood to your lungs, where it receives oxygen. Then, your heart pumps the oxygen- and nutrient-rich blood to the tissues and organs throughout your body.

Last reviewed by a Cleveland Clinic medical professional on 04/29/2022.

References

  • American Heart Association. How the Healthy Heart Works. (https://www.heart.org/en/health-topics/congenital-heart-defects/about-congenital-heart-defects/how-the-healthy-heart-works) Accessed 4/29/2022.
  • InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the blood circulatory system work? (https://www.ncbi.nlm.nih.gov/books/NBK279250/) 2010 Mar 12 [Updated 2019 Jan 31]. Accessed 4/29/2022.
  • National Heart, Lung, and Blood Institute. How the Heart Works. (https://www.nhlbi.nih.gov/health-topics/how-heart-works) Accessed 4/29/2022.

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