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9 Cards in this Set
- Front
- Back
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Descibe Atrial Systole |
• Blood under low pressure flows into the atria from the pulmonary vein and vena cava. • As the atria fill, the increasing pressure of the blood against the atrioventricular valves forces them open allowing blood to begin leaking into the ventricles. • The atria contract forcing more blood into the ventricles. |
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Describe Ventricular Systole |
• The ventricles contract from the base of the heart, increasing the pressure in the ventricles. • The increased pressure forces open the semi lunar valves and pushes blood up and out through the pulmonary artery and aorta. • The pressure of blood against the atrioventricular valves closes them and prevents blood flow back into the atria. |
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Describe Cardiac Diastole |
• The atria and ventricles relax. • Elastic recoil of the relaxing heart lowers pressure in the atria and ventricles. • Blood under high pressure in the pulmonary artery and aorta is drawn back towards the ventricles, closing the semi lunar valves which prevents backflow in to the ventricles. • Coronary Arteries fill during diastole. • low pressure in the atria draws blood from veins. |
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Why do the ventricles have thicker walls than the atria? |
The ventricles have to push blood out of the heart whereas the atria just need to push blood a short distance into the ventricles. |
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Why are the walls of the left ventricle thicker than in the right ventricle? |
The left ventricle must contract more powerfully to pump blood all the way around the body via the pulmonary artery, the right ventricle only needs to get blood to the lungs via the aorta. |
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What is the function of atrioventricular valves? |
• Link the atria to the ventricles. • To prevent backflow of blood into the atria when the ventricles contract. |
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What stops the AV valves being forced up into the atria when the ventricles contract? |
Cords attaching the AV valves to the ventricles. |
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What is the function of Semi-Lunar valves? |
• Link the ventricles to the pulmonary artery and aorta. • Prevents backflow into the heart when it relaxes. |
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How is heart rate calculated? |
60 ÷ Time taken to complete one cardiac cycle |
