How does the bloodstream work

With each heartbeat, the heart pumps blood throughout our bodies, carrying oxygen to every cell. After delivering the oxygen, the blood returns to the heart. The heart then sends the blood to the lungs to pick up more oxygen. This cycle repeats over and over again. The circulatory system is made up of blood vessels that carry blood away from and toward the heart. As the heart beats, you can feel blood traveling through the body at pulse points — like the neck and the wrist — where large, blood-filled arteries run close to the surface of the skin.

Sometimes medicine can be given to help a person make more blood cells. And sometimes blood cells and some of the special proteins blood contains can be replaced by giving a person blood from someone else.

This is called a transfusion say: trans-FEW-zyun. People can get transfusions the part of blood they need, such as platelets, RBCs, or a clotting factor. When someone donates blood, the whole blood can be separated into its different parts to be used in these ways. Everybody's blood is red, but it's not all the same. Request Appointment. Video: Heart and circulatory system. Products and services. Thank you for Subscribing Our Housecall e-newsletter will keep you up-to-date on the latest health information.

Please try again. Something went wrong on our side, please try again. Show references How the heart works. National Heart, Lung, and Blood Institute. Accessed Jan. Mayo Clinic Press Check out these best-sellers and special offers on books and newsletters from Mayo Clinic. Legal Conditions and Terms Any use of this site constitutes your agreement to the Terms and Conditions and Privacy Policy linked below.

Advertising Mayo Clinic is a nonprofit organization and proceeds from Web advertising help support our mission. Advertising and sponsorship policy Advertising and sponsorship opportunities. Reprint Permissions A single copy of these materials may be reprinted for noncommercial personal use only. When it comes to circulating blood throughout your body, the left ventricle is the most important chamber in the heart.

The left ventricle is the largest of the four chambers and is responsible for generating the force necessary to propel your blood out of your aorta, the first artery your blood enters as it leaves your heart.

Your blood travels from your aorta through a series of smaller blood vessels until it reaches your capillaries. Before reaching your capillaries, however, blood must travel through the arterioles, where its speed and pressure are constantly adjusted as different segments of the arterioles change diameter in response to pressure and chemical sensors positioned nearby. These sensors adjust blood flow via the arterioles in response to changing conditions in your body.

Because of arteriole action, by the time your blood reaches your capillaries, it is no longer traveling in a pulsing fashion. Blood flows continuously through the capillaries, it does not "squirt" and "pause" as your heart beats. This continuous flow is necessary because there is a constant exchange of oxygen and nutrients happening in the capillary walls.

No cell in the body is far from a capillary. As blood travels through the capillaries, its supply of oxygen is reduced and has picked up waste products as well. From the capillaries, blood enters the venules, the veins, and then travels back to the heart to be refreshed and sent out once again.

In conclusion, your heart works like a pump which provides nutrients to every organ, tissue, and cell throughout your body. In turn, your cells dump waste products, like carbon dioxide, back into your blood to be returned to your heart.

Looking to start a diet to better manage your high blood pressure? A wall called the interventricular septum is between the two ventricles. The two top chambers are the right atrium and the left atrium. They receive the blood entering the heart. A wall called the interatrial septum is between the atria. The atria are separated from the ventricles by the atrioventricular valves: The tricuspid valve separates the right atrium from the right ventricle.

The mitral valve separates the left atrium from the left ventricle. Two valves also separate the ventricles from the large blood vessels that carry blood leaving the heart: The pulmonic valve is between the right ventricle and the pulmonary artery, which carries blood to the lungs. The aortic valve is between the left ventricle and the aorta, which carries blood to the body.

What Are the Parts of the Circulatory System? Two pathways come from the heart: The pulmonary circulation is a short loop from the heart to the lungs and back again. The systemic circulation carries blood from the heart to all the other parts of the body and back again. In pulmonary circulation: The pulmonary artery is a big artery that comes from the heart. It splits into two main branches, and brings blood from the heart to the lungs.

At the lungs, the blood picks up oxygen and drops off carbon dioxide. The blood then returns to the heart through the pulmonary veins.

In systemic circulation: Next, blood that returns to the heart has picked up lots of oxygen from the lungs. So it can now go out to the body. The aorta is a big artery that leaves the heart carrying this oxygenated blood.