How the Heart Functions While Exercising: Effects of Exercise on Cardiac Muscle

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How Your Heart Works During Exercise

How does your heart work during exercise? Before that question can be answered, one must know how the heart functions in general. The heart is a small, yet extremely important muscle that is located in your chest, slightly to the left. Its job is to circulate blood through out the body. To accomplish this the heart acts as a pump.

In order to act like a pump, the heart is divided into four separate chambers. The 2 chambers on the top are called atria and the 2 chambers on the bottom are called ventricles. There is a thick wall of muscle called the septum that separates the right and left sides. The purpose of the septum is to not allow blood to flow back and forth across atria or ventricles. Each chamber of the heart also contains valves. These valves keep blood flowing in one direction as they act as trap doors. Here is how your heart actually circulates your blood: First deoxygenated blood returns from the body and fills the right atrium. When the heart contracts the blood is forced through a valve into the right ventricle. Again, when the heart contracts the blood is forced through a valve called the pulmonary semilunar to the pulmonary artery. This artery takes the blood to the lungs where it is cleaned (CO2 in the blood is exchanged for oxygen).

Oxygen rich blood from the lungs then enters the left atrium. When it is full, the pressure from the blood will force the valve near the bottom to open, allowing the blood to flow down into the left ventricle. Then when the heart contracts again, the blood will be forced through the aortic valve, into the aorta, the biggest artery in the body. The blood will then be distributed to the entire body through smaller arteries and capillaries.

Now that you know exactly how the heart works, it will be very easy to understand how the heart works during exercise. Exercise basically causes your heart to pump more blood at a quicker pace. When you exercise, your muscles contract. In order for them to contract they must have oxygen. The more intense the exercise, the more intense the muscle contractions are. The more intense the muscle contractions are, the more oxygen that is needed. Needing an increased supply of oxygen also means needing an increased supply of blood as oxygen is carried to the muscles via blood. An increase in the flow of blood occurs because as you begin to exercise, sympathetic nerves cause the heart to beat faster and more forcefully. Sympathetic nerves also cause veins to constrict (get smaller). Narrower veins, but more blood coming through them at a faster rate results in a vastly greater amount of blood being pumped. The average resting heart pumps about 5 liters per minute. An exercising heart can pump about 5 times that amount or 25 liters per minute. So to sum it all up, the harder you work, the harder your heart works.