THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The cardiac cycle includes two phases: diastole and systole (Fig. 1.4). In the diastole phase, blood returns to the heart from the superior and interior vena cava and flows into the right atrium. The pressure in the right atrium increases as blood flows into it.

Detailed explanation-2: -Immediately after the blood inertia is overcome, the elevated pressures in the aorta and the pulmonary artery push the blood back toward the ventricles to close the semilunar valves. The atrioventricular valves are closed because the pressure in the atria is lower than the ventricular pressure (fig. 3.1). relaxation.

Detailed explanation-3: -Passive atrial filling terminates the x descent which is followed by the v wave, which occurs near the end of (right) ventricular systole (the peak of atrial pressure).

Detailed explanation-4: -Each cardiac cycle has a diastolic phase (also called diastole) where the heart chamber is in a state of relaxation and fills with blood that receives from the veins and a systolic phase (also called systole) where the heart chambers are contracting and pumps the blood towards the periphery via the arteries.