Answer:
ventricular pressure increases and ventricular volume remains the same.
Explanation:
The first phase of systole is the phase of isovolumetric contraction, where a sudden increase in intraventricular pressure is generated, causes the closure of the atrioventricular valves, and accumulates enough pressure to open the semilunar valves (pulmonary and aortic). In this phase the tension of the heart muscle wall increases but without shortening, so there is no emptying of the heart and the volume is maintained, and the pressure reaches that existing in the great vessels (pulmonary artery and aorta).
