06-12-2007, 16:06
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חבר מתאריך: 02.12.05
הודעות: 1,298
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ואחרי שהשפעת היין חלפה לה...
What are heart valves?
The heart consists of four chambers, two atria (upper chambers) and two ventricles (lower chambers). There is a valve through which blood passes before leaving each chamber of the heart. The valves prevent the backward flow of blood. These valves are actual flaps that are located on each end of the two ventricles (lower chambers of the heart). They act as one-way inlets of blood on one side of a ventricle and one-way outlets of blood on the other side of a ventricle. Each valve actually has three flaps, except the mitral valve, which has two flaps. The four heart valves are: - <LI class=" l-first">
tricuspid valve: located between the right atrium and the right ventricle pulmonary valve: located between the right ventricle and the pulmonary artery mitral valve: located between the left atrium and the left ventricle aortic valve: located between the left ventricle and the aorta
How do the heart valves function?
As the heart muscle contracts and relaxes, the valves open and shut, letting blood flow into the ventricles and atria at alternate times. The following is a step-by-step illustration of how the valves function normally in the left ventricle: - <LI class=" l-first">
After the left ventricle completes its contraction phase, the aortic valve closes and the mitral valve opens, to allow blood to flow from the left atrium into the left ventricle.
As the left atrium contracts, more blood flows into the left ventricle.
When the left ventricle completes it's contraction phase again, the mitral valve closes and the aortic valve opens, so blood flows into the aorta.
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נערך לאחרונה ע"י דוק05 בתאריך 06-12-2007 בשעה 16:14.
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