 That's the contraction of the ventricles that's pumping blood into the lungs and into the aorta, into the body. And then that little rest is where you have the diastolic pressure, which is the lower number. And then you get the systolic contraction again and you get the higher number. Now, I said high blood pressure should be determined only after several blood pressure readings. I've said that in the past and I say it again. To go get