THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -Rapid ejection (b-c): As the semilunar valves open at point (b), there is a rapid ejection of blood due to increased ventricular contractility. The arterial pressure increases until reaching it maximum at point (c). This phase usually lasts for 13% of the cardiac cycle.

Detailed explanation-2: -The semilunar valves open when the ventricular muscle contracts and generates blood pressure within the ventricle higher than within the arterial tree. When the heart muscle relaxes the diastole phase begins again.

Detailed explanation-3: -Ejection begins when the intraventricular pressures exceed the pressures within the aorta and pulmonary artery, which causes the aortic and pulmonic valves to open.

Detailed explanation-4: -During systole, the aortic and pulmonic valves open to permit ejection into the aorta and pulmonary artery.