cardiac cycle

`What occurs at the area labeled "C" on the graph?

AV valve closes

What occurs at the circle labeled "3" on the graph?

atrial diastole and ventricle systole

What occurs at the area labeled "B" on the graph?

Semilunar valve closes.

What occurs at "A" on the graph?

Semilunar valve opens.

What occurs at the circle labeled "4" on the graph?

isovolumetric ventricular contraction

What occurs at the circle labeled "7" on the graph?

isovolumetric ventricular relaxation

What occurs at the circle labeled "5" on the graph?

peak systolic pressure

What volume is labeled "E" on the graph?

stroke volume

What volume is labeled "F" on the graph?

end-diastolic volume

What volume is labeled "G" on the graph?

end-systolic volume

What is occurring in the left atrium at the circle labeled "2" on the graph?

Left atrium is in systole.