NEET 2026
- Exam
- NEET
- Year
- 2026
- Subject
- Biology
- Chapter
- Chapter
NEET 2026 · Biology · Chapter
During the beginning of ventricular diastole, as the ventricular...
During the beginning of ventricular diastole, as the ventricular pressure declines, a distinct acoustic event is detected through a stethoscope. Which of the following correctly identifies this event and its primary anatomical cause?
Options
- AFirst heart sound (lub) caused by the closure of the bicuspid and tricuspid valves
- BSecond heart sound (dub) caused by the closure of the semilunar valves
- CFirst heart sound (lub) caused by the opening of the atrioventricular valves
- DSecond heart sound (dub) caused by the opening of the semilunar valves
Correct answer
B. Second heart sound (dub) caused by the closure of the semilunar valves
Step-by-step solution
During the beginning of ventricular diastole, the ventricles relax and the ventricular pressure falls below the pressure in the aorta and pulmonary artery.
This pressure difference causes the blood to attempt to flow back into the ventricles, which forces the semilunar valves to close.
The closure of the semilunar valves produces the second heart sound, known as 'dub'.
The first heart sound ('lub') is produced at the beginning of ventricular systole due to the closure of the atrioventricular (bicuspid and tricuspid) valves.
Answer: Second heart sound (dub) caused by the closure of the semilunar valves
This pressure difference causes the blood to attempt to flow back into the ventricles, which forces the semilunar valves to close.
The closure of the semilunar valves produces the second heart sound, known as 'dub'.
The first heart sound ('lub') is produced at the beginning of ventricular systole due to the closure of the atrioventricular (bicuspid and tricuspid) valves.
Answer: Second heart sound (dub) caused by the closure of the semilunar valves