What is the Difference Between Systole and Diastole?

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Systole and diastole are two phases of the cardiac cycle, which occur as the heart beats and pumps blood through a system of blood vessels. They are defined by the following characteristics:

  • Diastole: This is when the heart muscle relaxes, causing the chambers of the heart to fill with blood and blood pressure to decrease.
  • Systole: This occurs when the heart contracts to pump blood out, causing blood pressure to increase.

These two phases affect blood pressure differently:

  • Systolic pressure: This is the first number on a blood pressure reading and represents the amount of pressure experienced by the arteries while the heart is beating (systole).
  • Diastolic pressure: This is the second number on a blood pressure reading and represents the amount of pressure experienced by the arteries when the heart is relaxing (diastole).

Both systolic and diastolic pressure are important in monitoring heart health. However, studies have shown that high systolic pressure is associated with a greater risk of stroke and heart disease compared to elevated diastolic pressure. As a result, doctors tend to monitor systolic pressure more closely, especially in older patients.

Comparative Table: Systole vs Diastole

Systole and diastole are two phases of the cardiac cycle that occur as the heart beats, pumping blood through the system of blood vessels carrying blood to each part of the body. Here is a table summarizing the differences between systole and diastole:

Feature Systole Diastole
Definition Systole is the contraction of the heart muscle. Diastole is the relaxation of the heart muscle.
Blood Pressure Increases during systole. Decreases during diastole.
Heart Action The heart contracts, pumping blood out. The heart relaxes, filling with blood.
Duration Lasts for about four seconds. Lasts several times per minute and up to 430 ms.

In a blood pressure reading, systole is represented by the top number (also known as the systolic pressure), while diastole is represented by the bottom number (also known as the diastolic pressure).