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Questions and Answers
During ventricular systole, atrial pressure ____________________ as the atrial volume increases due to relaxation of atrial muscles.
During ventricular systole, atrial pressure ____________________ as the atrial volume increases due to relaxation of atrial muscles.
decreases
During ventricular systole, ventricular pressure increases drastically as ventricular walls ____________________ strongly.
During ventricular systole, ventricular pressure increases drastically as ventricular walls ____________________ strongly.
contract
Aortic pressure increases as blood is pumped into the aorta during ____________________ systole.
Aortic pressure increases as blood is pumped into the aorta during ____________________ systole.
ventricular
During atrial and ventricular diastole, atrial pressure ____________________ as blood begins to leave the filled-left atrium into the left ventricle.
During atrial and ventricular diastole, atrial pressure ____________________ as blood begins to leave the filled-left atrium into the left ventricle.
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Ventricular pressure recovers as blood fills the left ventricle from the left atrium during ____________________.
Ventricular pressure recovers as blood fills the left ventricle from the left atrium during ____________________.
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Aortic pressure ____________________ as blood leaves the aorta to other arteries during diastole.
Aortic pressure ____________________ as blood leaves the aorta to other arteries during diastole.
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The closure of ____________________ valves prevents backflow of blood into the ventricle.
The closure of ____________________ valves prevents backflow of blood into the ventricle.
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The atrioventricular valve is open during ____________________ diastole.
The atrioventricular valve is open during ____________________ diastole.
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The contraction of cardiac muscles during systole leads to a decrease in ____________________ volume.
The contraction of cardiac muscles during systole leads to a decrease in ____________________ volume.
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The relaxation of cardiac muscles during diastole leads to an increase in ____________________ volume.
The relaxation of cardiac muscles during diastole leads to an increase in ____________________ volume.
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Study Notes
Cardiac Cycle
- The cardiac cycle consists of two major periods: systole (contraction of the cardiac muscle and pumping of blood from the heart) and diastole (relaxation of cardiac muscle and refilling of blood)
- Normal heart beat rate is 72 beats per minute, with a duration of each complete cardiac cycle of 0.8 seconds
Phases of Cardiac Cycle
- Atrial systole (0.1s): contraction and emptying of both atria, both ventricles relax
- Ventricular systole (0.3s): contraction and emptying of both ventricles, both atria relax
- Atrial and ventricular diastole (0.4s): both atria and ventricles relax, refilling with blood
Sequence of Events in a Cardiac Cycle
- Atrial systole and ventricular diastole (0.1s): electrical impulse from SA node triggers both atria to contract, blood pressure of both atria increase, forcing atrioventricular valves open
- Atrial diastole and ventricular systole (0.3s): electrical impulse travels down bundle of His, ventricles contract, blood pressure of both ventricles increase, forcing semilunar valves open
- Atrial and ventricular diastole (0.4s): both atria and ventricles relax, refilling with blood
Events Producing 'Lub' and 'Dub' Sounds
- 'Lub' sound: produced when ventricles contract, forcing atrioventricular valves to close, and semilunar valves to open
- 'Dub' sound: produced when semilunar valves close due to increased pressure in aorta and pulmonary artery, causing blood to flow back towards ventricles
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Description
Understand the cardiac cycle, including systole, diastole, and the heartbeat rate. Learn about the three phases of the cardiac cycle and its duration.
