How blood circulate?

The heart pumps it.

I searched Google under the key words "blood circulation" to get these possible sources:

https://www.google.com/search?client=safari&rls=en&q=Blood+circulation&ie=UTF-8&oe=UTF-8

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.

http://www.hackcollege.com/blog/2011/11/23/infographic-get-more-out-of-google.html

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072434/

Blood circulation is a vital process in the human body that ensures the supply of oxygen, nutrients, and hormones to every part of the body while removing waste products. It is achieved through the circulatory system, which includes the heart, blood vessels (arteries, veins, and capillaries), and blood.

To understand how blood circulates, let's break it down into the following steps:

Step 1: The heart pumps oxygenated blood. The circulatory system starts with the heart, a muscular organ located in the chest. The heart has four chambers: two atria (left and right) and two ventricles (left and right). Deoxygenated blood, which has returned from the body, enters the right atrium and then passes into the right ventricle. From there, the right ventricle pumps the blood to the lungs to receive oxygen.

Step 2: Oxygenation of blood in the lungs. Once in the lungs, the deoxygenated blood releases carbon dioxide and picks up oxygen. This oxygen-rich blood returns to the heart.

Step 3: The heart pumps oxygenated blood to the body. The oxygenated blood enters the left atrium of the heart, passes into the left ventricle, and is then pumped out into the arteries.

Step 4: Blood carried by arteries. Arteries are large blood vessels that carry oxygenated blood away from the heart. They progressively divide into smaller vessels called arterioles.

Step 5: Blood reaches capillaries. Arterioles lead to tiny blood vessels called capillaries, where the exchange of oxygen, nutrients, and waste products with the body's tissues occurs. Capillaries are present throughout every organ and tissue in the body.

Step 6: Blood returns through veins. After oxygen and nutrients are delivered to the tissues, blood becomes deoxygenated and carries waste products. It then flows into venules (small veins) and gradually merges into larger veins that return the blood to the heart.

Step 7: Blood re-enters the heart. Deoxygenated blood returns to the heart via the superior vena cava (from the upper body) and inferior vena cava (from the lower body), entering the right atrium. The process starts again as the blood goes through the steps mentioned above.

In summary, blood circulation involves the heart pumping oxygenated blood through arteries to reach the body's tissues and organs. In the capillaries, the exchange of oxygen and nutrients takes place. Deoxygenated blood is then carried back to the heart via veins for oxygenation in the lungs, completing the cycle.