Question

What is the state of heart after end of second heart sound and beginning of first sound
again?
A. Ventricles remain in systole while auricles undergo first diastole and then systole.
B. Ventricles remain in systole while auricles undergo first diastole and then systole.
C. Ventricles in systole and then diastole while auricles remain in diastole
D. Ventricles remain in diastole while auricles remain in diastole.

Answer 1

Hint: There are mainly two types of heart sounds. First, one is called lub and the second one is called dub. The first heart sound is heard when the tricuspid and bicuspid walls are closed and the second one when semilunar valves are closed.

Step by step answer:There are four chambers in the heart. The upper chambers are called auricles and the lower ones are called ventricles. In the initial stage, all chambers are relaxed and the blood falls freely through the auricles to the ventricles. In this condition, the chambers of the heart is said to be in diastole. Now their atrial walls contract and the blood further falls to the ventricles. This is called atrial systole. The ventricle undergoes contraction and the first heart sound is heard by the closing of tricuspid and bicuspid valves. This state is called ventricular systole. At this period the atria have entered the diastolic phase. Now, the ventricles contract and blood flow to the semilunar valve. And the second sound is heard which is called dub coinciding with the ventricular diastole. At this time all areas are also in diastole. Thus, the time interval between the second heart sound and the first heart sound is characterized by the diastolic phase of all heart chambers.
Hence the correct option is D.

Note: Other than lub and dub, there are two more heart sounds. They are clinically significant because changes to these heart sounds show a disease condition of our heart.