systole

Examples of systole in the following topics:

• Measuring Blood Pressure

  • Measurement of blood pressure includes systolic pressure during cardiac contraction and diastolic pressure during cardiac relaxation.
  • A normal blood pressure would be 120 mmHg systolic over 80 mmHg diastolic.
  • Hypotension: under 90 mm Hg systolic and  under 60 mm Hg diastolic.Normal: 90-119 mm Hg systolic and 60-79 mm Hg diastolic.
  • Hypertensive: 140 mm Hg and above systolic and 90 mm Hg and above diastolic.
  • Therefore, hypertension is indicated when the systolic number is persistently over 140–160 mmHg and low blood pressure, or hypotension, is indicated when the systolic number is persistently below 90 mmHg.

• Cardiac Cycle

  • Pressure waves generated by the heart in systole, or ventricular contraction, move the highly elastic arterial walls.
  • Every single heartbeat includes three major stages: atrial systole, ventricular systole, and complete cardiac diastole.
  • Atrial systole is the contraction of the atria that causes ventricular filling.
  • Complete cardiac diastole occurs after systole.
  • Systolic blood pressure is always higher than diastolic blood pressure, generally presented as a ratio in which systolic blood pressure is over diastolic blood pressure.

• Introduction to Blood Pressure

  • There are two mechanisms that take place in the heart, diastole and systole.
  • Diastole is the relaxation of the chambers of the heart whereas systole is the contraction of the heart chambers.
  • Therefore, the systolic pressure will show the pressure that your heart emits when blood is forced out of the heart, while diastolic pressure is the pressure exerted when the heart is relaxed.
  • During each heartbeat, blood pressure varies between a maximum (systolic) and a minimum (diastolic) pressure.
  • A normal blood pressure should be around 120/80 to be accounted for at a safe level , with 120 being measured through systole, and 80 through diastole.

• Operation of Atrioventricular Valves

  • The atrioventricular valves separate the atria from the ventricles and prevent backflow from the ventricles into the atria during systole.
  • The atrioventricular (AV) valves separate the atria from the ventricles on each side of the heart and prevent backflow of blood from the ventricles into the atria during systole.
  • Atrial systole (contraction) increases the pressure in the atria, while ventricular diastole (relaxation) decreases the pressure in the ventricle, causing pressure-induced flow of blood across the valve.
  • The ring contracts at the end of atrial systole due to the contraction of the left atrium around it, which aids in bringing the leaflets together to provide firm closure during ventricular systole.
  • Blood passes through the tricuspid valve the same as it does through the bicuspid valve, based on a pressure gradient from high pressure to low pressure during systole and diastole.

• Operation of Semilunar Valves

  • During ventricular systole, pressure rises in the left ventricle.
  • When ventricular systole ends, pressure in the left ventricle drops rapidly, and the aortic pressure forces the aortic valve to close.
  • Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle exceeds the pressure in the pulmonary artery.
  • When ventricular systole ends, pressure in the right ventricle drops rapidly, and the pressure in the pulmonary artery forces the pulmonary valve to close.

• Hypertension

  • Hypertension is elevated blood pressure, clinically defined as at or greater than 140/90 (systolic/diastolic) mm/Hg.
  • Blood pressure involves two measurements, systolic and diastolic, which depend on whether the heart muscle is contracting (systole) or relaxed between beats (diastole).
  • Normal blood pressure at rest is within the range of 100-140mmHg systolic (top reading) and 60-90mmHg diastolic (bottom reading).

• Arterial Blood Pressure

  • A person's blood pressure is usually expressed in terms of the systolic pressure over diastolic pressure and is measured in millimeters of mercury (mmHg), for example 140/90.
  • In the past, hypertension was only diagnosed if secondary signs of high arterial pressure were present, along with a prolonged high systolic pressure reading over several visits.
  • In the past, most attention was paid to diastolic pressure; but nowadays it is recognized that both high systolic pressure and high pulse pressure (the numerical difference between systolic and diastolic pressures) are also risk factors.
  • In some cases, it appears that a decrease in excessive diastolic pressure can actually increase risk, due probably to the increased difference between systolic and diastolic pressures.
  • If systolic blood pressure is elevated (>140) with a normal diastolic blood pressure (<90), it is called "isolated systolic hypertension" and may present a health concern.

• Chambers of the Heart

  • The atria undergo atrial systole, a brief contraction of the atria that ejects blood from the atria through the valves and into the ventricles.
  • The chordae tendinae are elastic tendons that attach to the valve from the ventricles and relax during atrial systole and ventricular diastole, but contract and close off the valve during ventricular systole.
  • There are no atrial inlet valves to interrupt blood flow during atrial systole.
  • The atrial systole contractions are incomplete and do not block flow from the veins through the atria into the ventricles.
  • During ventricular systole, the ventricles contract, pumping blood through the semi-lunar valves into systemic circulation.

• Blood Pressure

  • The systolic pressure is defined as the peak pressure in the arteries during the cardiac cycle; the diastolic pressure is the lowest pressure at the resting phase of the cardiac cycle.
  • During systole, when new blood is entering the arteries, the artery walls stretch to accommodate the increase of pressure of the extra blood.
  • The blood pressure of the systole phase and the diastole phase gives the two readings for blood pressure .
  • For example, the typical value for a resting, healthy adult is 120/80, which indicates a reading of 120 mm Hg during the systole and 80 mm Hg during diastole.

• Electrocardiogram and Correlation of ECG Waves with Systole

  • The first wave on an ECG is the P wave, indicating atrial depolarization in which the atria contract (atrial systole).
  • The QRS complex refers to the combination of the Q, R, and S waves, and indicates ventricular depolarization and contraction (ventricular systole).