How does the Heart Function? By: Bhavesh Boyapati

The heart is a very complex organ. It pumps about 4-5 quarts of blood every minute through a system of blood vessels that are 60,000 miles long. That is roughly 2000 gallons of blood pumped every day. The heart works 24/7 and never takes a break. So have you ever wondered how such a complex organ actually function behind the scenes?

The main parts of the heart

Some basic information about the heart is that it is slightly larger than a clenched fist. An adult heart weighs 8-12 grams( 230-340 grams) and beats 72 times/min., it also pumps 21.5 billion times in 70 years which would add up to 35 million gallons or 132 liters.

The size of a real Human heart

The heart consists of 3 layers, the myocardium( The tough wall), Pericardium( The thin layer of tissue) and the endocardium lines the inside. The heart cavity is divided along the middle into right and left hearts. The upper chambers are called auricle or atriums and the lower chambers are called ventricles. The atriums receive the blood and the ventricles pump the blood to the rest of the body.

The layers of protection on the heart

Blood passes through the tricuspid valve which is then pumped through the pulmonary artery for oxygenation. Oxygenated blood enters heart through the left auricle, flows the bicuspid/mitral valve into the left ventricle, and is then pumped into the aorta and into the arteries of the body.

Valves in the body allow blood to flow in only one direction. The heartbeat is actually the alternating contractions and relaxations of the myocardium.

Stimulated by the Sinoatrial(S-A), a natural pacemaker, it causes the 2 auricles to contract, forcing blood into the ventricles. The contractions of the ventricles are caused by the atrioventricular or (A-V). After contractions the ventricles relax and the process starts all over again. The Sinoatrial works without conscious control and changes speed to factors such as exercise.

The typical, healthy heart sound is Lub-Dub... Lub-Dub...Lub-Dub. The sound comes from closing valves between auricles/Ventricles. Heart murmurs are a swishing or hissing sound and indicate that blood is leaking from a valve and might indicate a serious heart problem.


  1. Circulatory system. (2017). In Encyclopædia Britannica
  2. Heart. (2017). In Encyclopædia Britannica.
  3. Philadelphia, T. C. (2014, August 10). How the Normal Heart Works. Retrieved March 10, 2017

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