GROSS ANATOMY

Detailed explanation-1: -diastole, in the cardiac cycle, period of relaxation of the heart muscle, accompanied by the filling of the chambers with blood. Diastole is followed in the cardiac cycle by a period of contraction, or systole (q.v.), of the heart muscle.

Detailed explanation-2: -Diastole begins with the closing of the aortic valve (or pulmonic) and ends with the closing of the mitral valve (or tricuspid). This period encompasses the ventricular relaxation and filling. Diastole represents when the blood vessels return blood to the heart in preparation for the next ventricular contraction.

Detailed explanation-3: -Systole is the contraction phase of the cardiac cycle, and diastole is the relaxation phase.

Detailed explanation-4: -During ventricular contraction, the atria relax (atrial diastole) and receive venous return from both the body and the lungs. Then, in ventricular diastole, the lower chambers relax, allowing initial passive filling of the thick-walled ventricles and emptying of the atria.