Diastole:
Heart during ventricular diastole.
Diastole is the period of time when the heart fills with blood after systole (contraction). Ventricular diastole is the period during which the ventricles are relaxing, while atrial diastole is the period during which the atria are relaxing. The term diastole originates from the Greek word διαστολη, meaning dilation.[1]
[edit] Inside the heart
During ventricular diastole, the pressure in the (left and right) ventricles drops from the peak that it reaches in systole. When the pressure in the left ventricle drops to below the pressure in the left atrium, the mitral valve (atrioventricular bicuspid valve) opens, causing accumulated blood from the atrium to flow into the ventricle.
[edit] Inside the arteries
The adjective "diastolic" is used to refer to filling of the heart with blood between muscle contractions. It is used to describe the opposite portion of the cardiac cycle related to contraction. More typically it is used as one component of measurement of blood pressure. "Diastolic pressure" refers to the lowest pressure within the arterial blood stream occurring during each heart beat. The other component of blood pressure is systolic pressure, which refers to the highest arterial pressure during each heart beat.
When blood pressure is stated for medical purposes, it is usually summarized as a ratio of systolic to diastolic pressure; for example: 120/80 mmHg.
[edit] See also
[edit] References
- ^ diastole. Merriam-Webster Online Dictionary. 24 August 2008.
[edit] External links
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