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Questions and Answers
What occurs during the joint diastole of the heart?
What occurs during the joint diastole of the heart?
- All valves are closed, and blood flows out of the heart.
- The atrial muscles contract, pushing blood into the ventricles.
- The SAN generates an action potential.
- The ventricles fill with blood from the atria. (correct)
How much does atrial contraction increase blood flow into the ventricles?
How much does atrial contraction increase blood flow into the ventricles?
- 30 percent (correct)
- 20 percent
- 10 percent
- 40 percent
What role does the AV bundle play in the cardiac cycle?
What role does the AV bundle play in the cardiac cycle?
- It generates an action potential in the ventricles.
- It conducts the action potential to the ventricular musculature. (correct)
- It prevents backflow of blood into the atria.
- It causes relaxation of the atria.
What causes the closure of the tricuspid and bicuspid valves during ventricular systole?
What causes the closure of the tricuspid and bicuspid valves during ventricular systole?
What prevents backward flow of blood in the ventricles?
What prevents backward flow of blood in the ventricles?
What does an electrocardiogram (ECG) represent?
What does an electrocardiogram (ECG) represent?
What occurs to the atria during ventricular systole?
What occurs to the atria during ventricular systole?
What happens immediately after the SAN generates an action potential?
What happens immediately after the SAN generates an action potential?
What is the primary function of the bundle of His in the heart?
What is the primary function of the bundle of His in the heart?
During the cardiac cycle, when does the pressure in the ventricles decline?
During the cardiac cycle, when does the pressure in the ventricles decline?
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Study Notes
Cardiac Cycle
- The heart comprises four chambers that initially enter a state of joint diastole, relaxing simultaneously.
- Blood flows from pulmonary veins and vena cava into the left and right ventricles through open tricuspid and bicuspid valves, while semilunar valves remain closed.
- The sinoatrial node (SAN) generates an action potential, triggering simultaneous contraction of both atria (atrial systole), which increases blood flow into the ventricles by approximately 30%.
- The action potential, transmitted by the atrioventricular node (AVN) and bundle of His, stimulates ventricular muscles leading to contraction (ventricular systole).
- During ventricular systole, atria relax (diastole), and increased pressure in the ventricles causes tricuspid and bicuspid valves to close, preventing backflow.
- Ventricles are emptied as blood is pushed into the pulmonary artery (right side) and aorta (left side) through semilunar valves.
- Semilunar valves prevent backward flow of blood, maintaining pressure declines in the ventricles and preventing reverse flow into the aorta and pulmonary artery.
Electrocardiograph
- An electrocardiogram (ECG) is a graphical representation of the heart's electrical activity throughout a cardiac cycle.
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