ANATOMY

Detailed explanation-1: -In atrial systole, both the atria contract simultaneously, and the blood pass into the ventricles which are in a relaxed state. Bicuspid and tricuspid valves are open during both joint diastole and atrial systole. The opening of atrioventricular valves allows the blood to flow from the atria to the ventricles.

Detailed explanation-2: -The atrial systole is the last phase of a diastole during which the ventricular filling is completed. The atrioventricular valves are open; the semilunar valves are closed (fig.

Detailed explanation-3: -The tricuspid valve functions as a one-way valve that closes during ventricular systole to prevent regurgitation of blood from the right ventricle back into the right atrium. It opens during ventricular diastole, allowing blood to flow from the right atrium into the right ventricle.

Detailed explanation-4: -The tricuspid and the biscuspid valves open due to the pressure exerted by the simultaneous contraction of the atria. Blood moves freely from atrium to the ventricle during joint diastole.

Detailed explanation-5: -Heart Sounds The first heart sound (S1) represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole (point a). S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously.