Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Management of acute coronary syndrome wikipedia , lookup
Heart failure wikipedia , lookup
Electrocardiography wikipedia , lookup
Coronary artery disease wikipedia , lookup
Quantium Medical Cardiac Output wikipedia , lookup
Mitral insufficiency wikipedia , lookup
Antihypertensive drug wikipedia , lookup
Jatene procedure wikipedia , lookup
Heart arrhythmia wikipedia , lookup
Lutembacher's syndrome wikipedia , lookup
Dextro-Transposition of the great arteries wikipedia , lookup
:::Index>Profound Human World>Knowledge Acquisition>Material Circulation> The Structure and Function of Heart The Structure and Function of Heart The blood circulates in the human body depending on the heartbeat. The heart, locating to the left side of the thoracic cavity, is the center of the cardiovascular system and a hollow organ formed with the muscles. Through the whole life, the heart like a living muscular bump propelling the blood forward by beating average 60~70 times per minute, totally about 100,000 times a day and 20 billion times a life. The human heart has four chambers, two above are atria and two below are ventricles. The left and right two chambers form two separate pumps not communicating with each other. And because ventricle contraction is the main power to propel the blood, so the muscle layers of the ventricles are thicker than the atria. Fig.1:The human heart The heart has several blood vessels connecting to the atria and the ventricles respectively. The vein connecting to the atrium conveys the blood into the heart. The artery connecting to the ventricle conveys the blood out of the heart. The blood circulating in the heart is directed by the valves. The valve is membranous structure and has several kinds including bicuspid valve (between the left ventricle and atrium), tricuspid valve (between the right ventricle and atrium) and semilunar valve (between the ventricle and aorta), all of them play like the guarders of the heart and only can open in one direction. When the atria contract, the bicuspid and tricuspid valves open to the ventricles for blood flowing into the ventricles; when the ventricles contract, the bicuspid and tricuspid valves close while the semilunar valve open for blood flowing out of the heart to the artery. How does the blood flow in and out of the heart? The heartbeat is not just a simple All rights reserved by National Taiwan Science Education Center action, actually it includes several phases to fill the heart with the blood and then pump the blood out. First, the atria and ventricles relax to allow the blood to flow in the ventricles; secondly, the atria contract along with the semilunar vale opening for the blood flowing into the ventricles; thirdly, the ventricles contract along with the semilunar vale closing for propelling the blood into the artery; finally, the ventricles relax and the semilunar vale closes. Each heartbeat or cardiac cycle will continue about 85 seconds and then repeat. The physician uses the stethoscope to examine the heartbeat for understanding the heart operation. Where does the “lub-dupp” sound come from when heart is beating? It just results from the heart vales closing. When the bicuspid and tricuspid valves close, the discharge of the blood against them makes the “lub” sound. Likewise, when the semilunar vale closes, the discharge of the blood against it makes the “dupp” sound. Reviewed by:Zhang, Yong-Ta、Liu, Hsin professor All rights reserved by National Taiwan Science Education Center