10 Questions
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.
contract
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.
decreases
Ventricular pressure recovers as blood fills the left ventricle from the left atrium during ____________________.
diastole
Aortic pressure ____________________ as blood leaves the aorta to other arteries during diastole.
decreases
The closure of ____________________ valves prevents backflow of blood into the ventricle.
semilunar
The atrioventricular valve is open during ____________________ diastole.
atrial
The contraction of cardiac muscles during systole leads to a decrease in ____________________ volume.
ventricular
The relaxation of cardiac muscles during diastole leads to an increase in ____________________ volume.
ventricular
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
Understand the cardiac cycle, including systole, diastole, and the heartbeat rate. Learn about the three phases of the cardiac cycle and its duration.
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