Question

Both atria and ventricles are made of the same cardiac μscle tissue. Because most of the pumping work is done by the ventricles, systole and diastole always refer to the activity of the ventricles unless otherwise. Each phase of the cardiac cycle with its characteristic event.

Answer 1

During the cardiac cycle, diastole refers to the relaxation phase where the atria contract and pump blood into the ventricles, while the ventricles relax and fill with blood from the atria. Systole is the contraction phase, where the atria relax and collect blood from the lungs and body, while the ventricles contract and pump blood out of the heart.

Step-by-step explanation:

In the cardiac cycle, diastole refers to the period of relaxation in which the atria contract and pump blood into the ventricles, while the ventricles relax and fill with blood from the atria. Systole, on the other hand, refers to the period of contraction in which the atria relax and collect blood from the lungs and body, while the ventricles contract and pump blood out of the heart.

During diastole, the ventricles are filled with approximately 70-80 percent of their capacity due to inflow during diastole. Atrial contraction, also known as the "atrial kick", contributes the remaining 20-30 percent of filling. Atrial systole lasts approximately 100 ms and ends prior to ventricular systole, as the atrial muscle returns to diastole.

Both atria and ventricles undergo systole and diastole, and it is essential that these components be carefully regulated and coordinated to ensure efficient blood pumping.