38 Questions
What is the first heart sound (S1) caused by?
Closure of the AV valves when ventricles contract at systole
What is the term for the period of relaxation in the cardiac cycle?
Diastole
What happens to the semilunar valves during ventricular diastole?
They remain closed due to higher pressure in the large arteries
What is the primary function of the isovolumetric contraction phase?
To close the AV valves
What happens to the intraventricular pressure during isovolumetric relaxation?
It falls due to the relaxation of the ventricles
What is the maximum pressure in the left ventricle during systole?
120 mm Hg
What happens to the pressure in the ventricular cavities during the isovolumetric contraction phase?
It rises but remains less than that in the large arteries
What is the second heart sound (S2) caused by?
Closure of the aortic and pulmonary valves when ventricles relax at diastole
During what phase of the cardiac cycle is the third heart sound (S3) produced?
At middle one third of diastole
What is the duration of the cardiac cycle?
0.8 sec
What is the minimum pressure required in the left ventricle to open the aortic valves?
120 mm Hg
What is the pressure in the left ventricle at the end of rapid inflow?
2-4 mm Hg
What happens to the AV valves during ventricular diastole?
They close to prevent backflow of blood into the atria
What is the fourth heart sound (S4) associated with?
Atrial contraction
What happens to the semilunar valves during the isovolumetric contraction phase?
They remain closed to prevent blood from flowing out of the ventricles
What is the minimum pressure in the right ventricle during diastole?
2 mm Hg
In what type of heart is the fourth heart sound (S4) commonly heard?
All of the above
What characterizes the maximum ejection phase?
Ventricular pressure is greater than that in the large arteries
What is the pressure in the right ventricle at the end of rapid inflow?
0-2 mm Hg
What is the term for the period of contraction in the cardiac cycle?
Systole
What type of sound is the first heart sound (S1) described as?
Soft and low-pitched
What is the maximum pressure in the pulmonary artery during systole?
25 mm Hg
What happens to the blood in the aorta and pulmonary artery during the ventricular diastole phase?
It tends to move back into the ventricles
What happens during the reduced inflow phase of ventricular diastole?
Most of the blood has already entered the ventricles
What is the duration of ventricular systole?
0.3 sec
What marks the beginning of a new cardiac cycle?
The contraction of the atrial muscle fibers
What is the primary function of the ventricular diastole phase?
To relax the ventricles and decrease the intraventricular pressure
Why does the opening of a valve not produce a sound?
Because it is a slow-developing process
What is the term for the spontaneous generation of an action potential in the cardiac cycle?
Sinus node
During which phase of the cardiac cycle do the AV valves close?
Systole
What is the purpose of the isovolumetric relaxation phase?
To relax the ventricles and decrease intraventricular pressure
What happens to the intraventricular pressure during the reduced ejection phase?
It decreases, but is still higher than that in the aorta
What happens during the isovolumetric contraction phase?
Ventricular pressure increases
What marks the beginning of the cardiac cycle?
Beginning of one heart beat
What is the duration of the cardiac cycle?
0.8 seconds
During which phase of the cardiac cycle is Heart Sound 2 produced?
Ventricular diastole
What is the sequence of heart sounds in the cardiac cycle?
S4, S1, S2, S3
What is the duration of ventricular diastole?
0.5 seconds
Learn about the ventricular diastole stage of the cardiac cycle, where the ventricles relax and intraventricular pressure falls. Understand the role of semilunar and A-V valves in this process.
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