The cardiac cycle begins with atrial contraction, pushing blood into the ventricles. Then, ventricular contraction forces blood into the aorta/pulmonary artery, while AV valves close to prevent backflow. Finally, atria and ventricles relax, refilling the heart.
The cardiac cycle begins with atrial contraction, pushing blood into the ventricles. Then, ventricular contraction forces blood into the aorta/pulmonary artery, while AV valves close to prevent backflow. Finally, atria and ventricles relax, refilling the heart.
| Front | Starting with the heart full of blood outline the stages of the cardiac cycle. ( 5 marks) |
|---|---|
| Back | atria contract/atrial systole occurs; forces blood into ventricles; semilunar valves (in veins) prevent back flow; ventricles contract/ventricular systole occurs; forces blood into aorta/pulmonary artery; atrio-ventricular valves shut preventing back flow into atria; atria and ventricles then relax so heart fills with blood; semilunar valves (in arches) are closed at this stage |
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