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biology 0610printed 112 · PDF 112

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printed 112 · PDF 112

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112 Deoxygenated blood enters the heart through the vena cava into the right atrium Right atrium contracts and blood moves downwards through the tricuspid valve The right ventricle contracts and blood flows up into the pulmonary artery through the semilunar valve into the lungs The oxygenated blood returns to the left atrium entering through the pulmonary vein through the semilunar valve The left atrium contracts and blood moves into the left ventricle through the bicuspid valve The ventricle contracts and the oxygenated blood flows through to the aorta through the semilunar valve The left ventricle wall is much thicker so the blood flows out with much greater pressure than from the right ventricle as from the right atrium blood is transported only to lungs and with the aorta the whole body The two sides of the heart are separated by the septum keeping oxygenated blood on the left side and deoxygenated on the right side Bicuspid and tricuspid valves are called atrioventricular valves Valves ensure blood moves in one direction and no backflow occurs The pulmonary artery is the only artery which carries deoxygenated blood and the pulmonary vein is the only vein which carries oxygenated blood The coronary arteries supply the heart with oxygen Heart monitoring and CHD: An electrocardiogram (ECG) is used to monitor the heart Heart activity is also monitored through taking of a pulse During physical activity the pulse rate gets higher so more oxygen is transported around the body and quicker hence the increased pulse rate CHD is caused by a buildup of cholesterol in the coronary arteries which narrows the artery and restricts oxygen supply to the heart causing heart related problems and disease CHD is often caused by smoking, bad eating habits, age and stress Exercise reduces the risk of CHD a lot Blood vessels: Arteries carry oxygenated blood from the heart to the body. They have a small lumen but thick wall composed of elastic fibres to maintain high blood pressure. Arteries then branch into arteries and then capillaries.