Transport in animals

The graph below shows pressure changes in the left atrium, left ventricle, and aorta during one cardiac cycle of a healthy human at rest.

Pressure changes in the cardiac cycle

Which of the following statements correctly describes the state of the heart valves or blood flow at the indicated times?

At $T_1$ , the atrioventricular valve closes because the pressure in the left ventricle rises above the pressure in the left atrium.

Between $T_1$ and $T_2$ , both the atrioventricular valve and the semi-lunar valve are open to allow rapid ventricular filling.

At $T_3$ , the semi-lunar valve opens because the pressure in the aorta exceeds the pressure in the left ventricle.

Between $T_3$ and $T_4$ , blood flows from the left atrium into the left ventricle as the ventricle relaxes.

Transport in animals Questions

The graph below shows pressure changes in the left atrium, left ventricle, and aorta during one cardiac cycle of a healthy human at rest.

Pressure changes in the cardiac cycle

Which of the following statements correctly describes the state of the heart valves or blood flow at the indicated times?

At $T_1$ , the atrioventricular valve closes because the pressure in the left ventricle rises above the pressure in the left atrium.

Between $T_1$ and $T_2$ , both the atrioventricular valve and the semi-lunar valve are open to allow rapid ventricular filling.

At $T_3$ , the semi-lunar valve opens because the pressure in the aorta exceeds the pressure in the left ventricle.

Between $T_3$ and $T_4$ , blood flows from the left atrium into the left ventricle as the ventricle relaxes.