The circulatory system, also called the cardiovascular system, is responsible for distributing nutrients and oxygen to different parts of the body, with the heart working as the pump. As the heart contracts, it pumps blood into your blood vessels, which then circulate the blood to the body before it goes back again to the heart. The path of blood through the heart also makes up a major part of the circulation because the heart also needs to be nourished, and this is where both oxygenated and deoxygenated blood flow.

The heart is made of four chambers which receive and pump blood. In the heart, the two circuits of the circulatory system (pulmonary and systemic circulation) converge. Before blood flows to the various parts of the body, it circulates in the heart and passes through the lungs.In this article, we will describe thepath of blood through the heart and discuss the function of the heart as part of the circulatory system.

Basics Parts of the Heart

Understanding the function of the heart is helpful to learn more about its anatomy. Here are the basic parts of the heart:

1. Right Atrium

The heart can be divided into right and left halves, as well as into the upper and lower
chambers. There are two upper chambers called atria and two lower chambers called ventricles. On each side of the heart, there are one atrium and one ventricle. Blood from the body goes back to the heart via the right atrium.From the right atrium, blood will then pass through a valve called the tricuspid valve, to go to the next chamber. Valves are structures that make sure there is a one-way forward flow, thus keeping the blood from passing backward.

2. Right Ventricle

The right ventricle receives blood from the right atrium and pumps it to the lungs through the pulmonary arteries, which are guarded by another valve called the pulmonic valve.

3. Pulmonary Circulation

The pulmonary arteries distribute blood to the lungs. Blood circulates in the lungs, where oxygen (O2) is added to the bloodand carbon dioxide (CO2) is removed. Blood returns to the heart through the pulmonary veins, which go into the left chambers.

4. Left Atrium

The left atrium receive blood from the lungs and pushes it through the mitral valve to pass it into the left ventricle.

5. Left Ventricle

The left ventricle pumps blood to the rest of your body through the aorta, with blood passing through to theaortic valve.

6. Aorta

The aorta is the largest artery in the body, which delivers the blood to the rest of your body.

Path of Blood Through the Heart

1. The path of blood through the heart begins with the right atrium receiving blood, which has circulated through most of the body. This blood is relatively low in oxygen because most of it has already been delivered to different organs and tissues.
2. This blood is also relatively high in carbon dioxide, which is a product of metabolism in the tissues. Blood is delivered back to the right side of the heart by the large vein called the vena cava.
3. The right atrium empties the blood into the ventricle after passing through the tricuspid valve.
4. The muscular right ventricle pumps the blood into your lungs for oxygenation via the pulmonary arteries.
5. It is in the lungs that gas exchange takes place. Here, the capillaries (tiny blood vessels) will absorb carbon dioxide which then is replaced with oxygen.
6. Oxygenated blood flows back to the heart through the pulmonary vein, back into your left atrium.
7. From the atrium, oxygen-rich blood empties into the left ventricle through another valve (mitral valve).
8. The left ventricle is a powerful muscle that contracts to pump blood into the systemic circulation. Blood passes through the aortic valve and into the aortic arch, which gives off several branches that distribute blood to all parts of your body. These branches include:

• The carotid artery, which delivers blood to your brain
• The auxiliary arteries, which delivers blood to your upper extremities
• The descending aorta, which delivers blood to the lower parts of the body.

8. As blood is delivered to the organs and tissues, it passes through smaller blood vessels called capillaries, where it can easily distribute nutrients and oxygen, while removing wastes and carbon dioxide from the tissues.
9. Deoxygenated blood returns to the veins, to be brought back to the heart.
10. The path of blood through the heart is repeated, and blood is pumped to the body continuously.

Here is a video showing how the blood flow through path in the heart: 

How Does Blood Flow to Lungs?

Through the pulmonic valves, the blood can enter into your pulmonary. Then the blood starts the travel of pulmonary circulation.

From the right side of the heart, blood flows past the pulmonic valve to enter your lungs through the pulmonary circulation. It travels into the lungs through your pulmonary artery and passes into the tiny capillaries in the lungs. The capillaries have very thin walls that allow oxygen from the air sacs in your lungs to be absorbed, at the same time allowing carbon dioxide, a metabolic waste product, to pass from your blood into these air sacs. CO2 is then eliminated whenever you exhale. The oxygenated blood is sent back to the left side of the heart through your pulmonary veins.