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Understanding the Heart

The heart is a hollow muscular organ about the size of a fist. The heart's primary job is to pump blood throughout the body.
Because the heart is a muscle, it needs blood to function properly, which it gets from the coronary arteries. These arteries wrap around the outside of the heart, supplying oxygen and nutrient-rich blood to the heart muscle.
The inside of a normal heart is divided into four chambers:
  • Right atrium
  • Left atrium
  • Right ventricle
  • Left ventricle.
Blood, in need of oxygen, flows in from the body and enters the right atrium. From the right atrium, blood is squeezed into the right ventricle through one of the heart's valves.
Heart valves keep blood flowing in a one-way direction by opening to let the proper amount of blood flow through and then closing to prevent backflow.
From the right ventricle, blood is pumped through another valve and then into the lungs, where it receives oxygen. Flowing back to the heart into the left atrium, the blood is then squeezed into the left ventricle through the mitral valve. From there, the oxygen-rich blood is pumped through the aortic valve and into the aorta, where it flows to the rest of the body.

Understanding Heart Disease

Heart disease in the coronary arteries (also known as coronary artery disease, or CAD) occurs when they become clogged from a buildup of cells, fat, and cholesterol. This buildup is called plaque. As the inside of the coronary arteries gather plaque and narrow, they decrease the flow of blood and oxygen that nourishes the heart muscle. This narrowing and hardening of the arteries is known as atherosclerosis.
Heart muscle requires blood and oxygen to function properly. When you are doing a physical activity or something that is stressful to you, your heart muscle demands more blood and oxygen. However, if the coronary arteries are narrowed, this need cannot always be met. As a result, you may experience heart disease symptoms such as angina, or chest pain, irregular heartbeats, and shortness of breath. These symptoms of heart disease may be temporary and last for only a few minutes. This happens because your heart is experiencing ischemia, which is a temporary lack of oxygen.
However, the longer the heart muscle goes without oxygen, the more serious the consequences. This is the case when arteries become blocked. Over time, the areas that are not getting enough nourishment can be permanently damaged, meaning that the heart tissue dies. This is what occurs with a heart attack.
Besides leading to a heart attack, lack of oxygen can also result in serious irregular heart rhythms and even loss of life.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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