Pumping Blood: The Circulatory System


Take a second to listen to your heartbeat. If you were to count the number of beats you heard per day it would sum up to around 100,000. Not to mention that all of those beats correlate to the pumping of blood, which means you are pumping about 2,000 gallons of blood through your heart daily. Obviously you don’t have 2,000 gallons of fluid inside you, so the system is designed like a loop. The circulatory system cycles the blood in the body to maintain oxygen, carbon dioxide, nutrient, waste, and hormone levels so that all other systems can properly function.

Basic Anatomy of the Circulatory System

The circulatory system is a vast network of tube-like structures called blood vessels that carry blood around the body. The main organ responsible for getting the blood to its appropriate location is the heart. The heart uses arteries and veins to transport blood around the body. The arteries and veins meet at capillaries, which are very thin tubes that slow blood flow to allow for exchange of gases. There are capillaries throughout the body’s tissues and even in the lungs. 

There are three loops in the circulatory system: the systemic circulation, the pulmonary circulation, and the coronary circulation. The systemic circulation loop covers the entire body, including the limbs and head. Oxygen is delivered to cells and tissues via the arteries and carbon dioxide is returned through the veins. Next, the pulmonary circulation takes deoxygenated blood from the veins and reoxygenates it by passing through the lungs and then returning to the heart to be pumped back into the systemic circulation. Lastly, the coronary circulation loop ensures the heart and its thick muscle tissue are well oxygenated to continually pump blood. The basic flow of blood in the body is expressed in the diagram below:

The Heart

Jogging is a great way to get the heart pumping!

The heart is the driving force behind the entire circulatory system. The human heart has four chambers: the left atrium, right atrium, left ventricle, and right ventricle. The atria are areas where blood collects to be emptied into the ventricle. The ventricle contracts once filled to pump blood away from the heart. Follow the path blood takes through the heart with the numbers on the picture and steps listed below:

  1. The superior and inferior vena cavas dump deoxygenated blood into the right atrium
  2. The right atrium squirts the blood into the right ventricle through the right AV valve
  3. The right ventricle contracts
  4. Blood is pumped through the left and right pulmonary arteries
  5. Blood is reoxygenated in the lungs
  6. Oxygenated blood returns from the lungs and dumps into the left atrium
  7. Once full, the right atrium squirts blood into the left ventricle through the left AV valve
  8. The left ventricle contracts
  9. Blood is pushed through aortic valve
  10. Oxygenated blood is pumped to the body

Want to know more about your body? Check out this article!

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