APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -The heartbeat is caused by the heart muscles relaxing and contracting. During this cycle, the period of relaxation is called diastole and the period of contraction is called systole.

Detailed explanation-2: -Cardiac cycle events can be divided into diastole and systole. Diastole represents ventricular filling, and systole represents ventricular contraction/ejection.

Detailed explanation-3: -systole, period of contraction of the ventricles of the heart that occurs between the first and second heart sounds of the cardiac cycle (the sequence of events in a single heart beat). Systole causes the ejection of blood into the aorta and pulmonary trunk.

Detailed explanation-4: -So, the correct answer is, ‘Systole. ‘ Additional Information: Lub or systolic sound is the first heart sound. It is heard at the beginning of the ventricular systole and is due to the rapid closing of the atrioventricular (between atria and ventricles) valve.