NEET 2015
- Exam
- NEET
- Year
- 2015
- Subject
- Zoology
- Chapter
- Body Fluids and Circulation
NEET 2015 · Zoology · Body Fluids and Circulation
Doctors use a stethoscope to hear the sounds produced during each...
Doctors use a stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when:
Options
- AVentricular walls vibrate due to gushing in of blood from atria
- BSemilunar valves close down after the blood flows into vessels from ventricles
- CAV node receives signal from SA node
- DAV valves open up
Correct answer
B. Semilunar valves close down after the blood flows into vessels from ventricles
Step-by-step solution
During each cardiac cycle two prominent sounds are produced which can be easily heard through a stethoscope. There are two prominent heart sounds:
- The first sound is of low intensity, lub, which is associated with the closure of mitral and tricuspid valve. This is the beginning of ventricular systole.
- The second sound is of higher intensity, dup, which is associated with the closure of semilunar valves and mark the end of ventricular systole.