what does diastolic blood pressure measure

Diastolic blood pressure measures the pressure in your arteries when your heart rests between beats. Blood pressure is measured using two numbers: the first number, called systolic blood pressure, measures the pressure in your arteries when your heart beats, while the second number, called diastolic blood pressure, measures the pressure in your arteries when your heart rests between beats. In a blood pressure reading, the systolic number always comes first and then the diastolic number. The diastolic reading, or the bottom number, is the pressure in the arteries when the heart rests between beats. This is the time when the heart fills with blood and gets oxygen.