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10 Cards in this Set
- Front
- Back
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Explain how heart valves open and close.
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The hearts valves open when the pressure is highest behind the valve, forcing it open and it closes when the pressure infront of the valve is highest.
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Describe how the heart beat is controlled.
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Electrical activity is sent from the SAN (sino-atrial node) to the atria and the AVN (atrio-ventricular node). The AVN delays that signal so that the atria can empty fully before it send the signal down the bundle of His and through the purkyne fibres. The ventricles then contract from the bottom up.
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What is the equation for cardiac output?
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Cardiac output = heart rate x stroke volume
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Explain what happens during atrial systole.
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Ventricles are relaxed and the semi lunar valves are shut. The atrioventricular valves are open because atrial pressure exceeds ventricle pressure. The atria contract and blood moves into the ventricles.
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Explain what happens during Ventricular systole.
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Atrioventricular valves are shut and the semi lunar valves are open. The ventricles contract and blood is pushed though the arteries.
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Explain what happens during diastole
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The atria and ventricles relax. The semi lunar valves are shut due to high pressure in the arteries. Blood starts to flow into the atria and as it does this the pressure of the atria exceeds that of the ventricles and so the AV valves open allowing blood to flow passively into the ventricles.
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What is an anuerysm?
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A balloon like structure that is caused by weakened arterial walls.
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What is thrombosis?
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Formation of a blood clot which can restrict and sometimes block blood from flowing through the arteries- causes increased BP.
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How is an atheroma formed?
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Damage occurs to the endothelium. This causes White blood cells and lipids to flood to the area causes a clump under the endothelium lining, forming fatty streaks. Over time this forms a plaque called an atheroma. This partially blocks the artery and so leads to increased BP.
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How can smoking lead to heart attacks?
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Carbon monoxide can bond to haemoglobin to form Carboxyhaemoglobin, this means less oxygen attaches to it. This means cells don't get as much oxygen for repiration and if heart muscle cells don't recieve anough oxygen it can lead to myocardial infarction.
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