Question
Biology Question on body fluids and circulation
The heart sound 'dup' is produced when
A
mitral valve is closed
B
semi-lunarval ves at the base of aorta get closed
C
tricuspid valve is opened
D
mitral valve-is opened.
Answer
semi-lunarval ves at the base of aorta get closed
Explanation
Solution
The kdup sound is produced by the closure of the semilunar valves at the start of ventricular relaxation. It lasts for 0.1 seconds and its principle frequency is 50 cycles/sec. It is higher pitched, louder, sharper and of short duration as compared to 'lub'. The semilunar valves close to prevent any back flow of blood from aorta to the ventricles.