Which one of the following is a matching pair ?

Options

A. Lub - sharp closure of AV valves at the beginning of ventricular systole
B. Dup- sudden opening of smilunar valves at the beginning og ventricular diastole
C. Pulsation of the radial artery- valves in the blood vessels
D. Initiation of the heart beat - Purkinje fibres

Answer

A

Explanation

During ventricular systole, the contraction of ventricular muscles causes the closure of bisuspid and tricuspid valves (AV valves), producing a low pitched 'lub' sound. At the end of ventricular systole, semilunar valves close, producing the second heart sound the 'dup'. Pulsation of the radial artery is due rhythmic contraction and relaxation in the aorta. Initiation of the heartbeat occurs in the SA node.