Physiology
Understanding the Heart
Before going into slightly more complicated physiology, it is important to understand the basic mechanics behind the circulatory system. The picture to the right shows a simple diagram showing the movement of blood throughout the body.
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Oxygenated blood travels from the lungs to the heart. It enters the heart into the left atrium (L.A.). It then passes through the bicuspid valve, into the left ventrical (L.V.).
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Oxygenated blood travels through the body to be utilized.
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Deoxygenated blood from the body (periphery) goes back to the heart. It enters the heart through the right atrium (R.A.). It then travels through the tricuspid valve, and into the right ventricle (R.V.).
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Deoxygenated blood leaves the left ventricle and travels to the lungs, where gas exchange occurs and the blood loses carbon dioxide and replaces it with oxygen.
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Why Issues stem from Valvular Dysfunction
There are two main types of valves: atrioventricular valves (between the atria and ventricles), and semilunar valves (between the ventricles and the vessels leaving the heart).
- The valve between the left atrium and left ventricle is called the bicuspid valve.
- The valve between the right atrium and the right ventricle are called the tricuspid.
- The valve between the left ventricle and the periphery is called the aortic semilunar valve.
- The valve between the right ventricle and the pulmonary artery is called the pulmonic semilunar valve.
Heart valves are meant to provide one-way directional flow of blood. Therefore, problems arise when blood either cannot flow properly (stenosis), or does not flow in only one direction (regurtitagion).
Valves must open and close in certain orders and at certain times to prevent issues and allow for proper heart functioning.
Atrioventricular valves must open as the ventricles relax, in order to allow the ventricles to fill with blood. As the ventricles begin to contract, the atrioventricular valves must close as to prevent blood from flowing backwards into the atrium. Blood leaking backward is regurgitation. When blood regurgitates, it often creates heart murmurs.
When the ventricles contract, the semilunar valves need to open to allow the blood to leave the ventricles. If any valves cannot open, they are stenoic. The semilunar valves must close as the ventricle relaxes and fills with blood coming from the atrium.
Fun Fact!
When your doctor listens to your heart beat, they listen for two sounds in every heart cycle:
1. "Lub" : the noise made by the closing of the atrioventricular valves
2. "Dub" : the noise made by the closing of the semilunar valves