Dictionary:

systole

  (sĭs'tə-lē)

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The rhythmic contraction of the heart, especially of the ventricles, by which blood is driven through the aorta and pulmonary artery after each dilation or diastole.

[Greek sustolē, contraction, from sustellein, to contract. See systaltic.]

The period of contraction of the heart. The term specifically designates the contraction of the ventricles, as distinguished from auricular contraction. It occurs with the first heart sound. The pressure from the systolic contractions is taken up and stored as potential energy by the elastic properties of the aorta and other great vessels of the arterial system. This storage of energy protects the smaller, more fragile vessels from undue pressure. The even flow and steady pressure of the blood are sustained by the controlled release of the potential energy stored in the arterial walls into kinetic energy for movement of the blood during the diastolic phase of heart function. The pressure recorded at the height of the ventricular contraction is the systolic pressure. In the adult the normal blood pressure is 120/80 mm Hg (systolic/diastolic). It rises with advancing age to 135/89 at 60 years of age. See also diastole; pressure, blood, stage; and pressure, systolic blood.

The phase of the cardiac cycle during which cardiac muscle contracts. Atrial systole concerns simultaneous contraction of the two atria and produces the pressure which pumps blood into the ventricles; during ventricular systole, the ventricles contract and pump blood to the lungs and rest of the body. Typically, systole lasts about 0.3 s in a resting adult man.

The contraction, or period of contraction, of the heart, especially of the ventricles, during which blood is forced into the aorta and pulmonary artery.

• atrial s. — contraction of the atria by which blood is forced into the ventricles; it precedes the true or ventricular systole.
• extra s. — see extrasystole.
• ventricular s. — contraction of the ventricles, forcing blood into the aorta and pulmonary artery.

Systole can mean the following:

• Systole (medicine) is a term describing the contraction of the heart.
• Systole (mathematics) is a term used in mathematics.
• Systole (literature) is a term used to describe entry into the imagination/surreal in a text.

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