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      • The cardiac cycle is the series of contractions in the heart that pressurize different chambers, causing blood to flood in one direction. There are two stages during the cardiac cycle. During diastole, the ventricles relax and fill with blood. The muscles contract during systole, pushing blood through the arteries.
  1. Oct 30, 2023 · The cardiac cycle is defined as a sequence of alternating contraction and relaxation of the atria and ventricles in order to pump blood throughout the body. It starts at the beginning of one heartbeat and ends at the beginning of another.

    • Content Manager
    • 15 min
    • Cardiac Cycle Explained
    • Cardiac Cycle Phases
    • The Cardiac Cycle Video

    The cardiac cycle varies in different organisms, due to changes in the structure of the heart. Fish have a two-chambered heart, with unidirectional flow.Some organisms have a three-chambered heart, which consists of the sinus venosus, atrium, and ventricle. This is seen in organisms such as reptiles and amphibians. Mammals and birds have developed ...

    The two main phases of the cardiac cycle are systole and diastole, and they follow each other in sequence. Each stage in the cardiac cycle contains important stepswhich direct the flow of blood properly. These steps include contractions of heart chambers and the proper opening and closing of specific heart valves.

    The entire cardiac cycle can be seen in the following animation, which tracts the cardiac cycle along with the pressure and volume of different chambers. An import tool to measure the cardiac cycle is the electrocardiogram, which can be seen as the green line on the above graph. The electrocardiogram is a signal which can be measured by sensitive m...

    • Gabe Buckley
    • Atrial Systole. This phase is also known as presystole or the last rapid filling phage or atrial kick and is the phase when the atria contract to pump the blood out of the atria into the ventricles.
    • Ventricular Systole. It is the stage when the ventricle contracts expelling the blood outside of the ventricles. The Purkinje fibers relay the cardiac impulses all over the ventricular wall stimulating the ventricular wall to contract.
    • Protodiastole. It is the intermediary stage which indicates the end of systole and the beginning of the diastole stage. The ventricular ejection will have completely reduced the ventricular pressure making it lower than the blood pressure inside the major arteries.
    • Atrial Diastole. It is the stage when the atria are filled. During this stage, the AV valves are closed and the superior and the inferior vena cava pours in the deoxygenated blood collected from the body tissue to the right atrium; whereas the pulmonary veins bring the re-oxygenated (purified) blood to the left atrium.
  2. The cardiac cycle comprises a complete relaxation and contraction of both the atria and ventricles, and lasts approximately 0.8 seconds. Beginning with all chambers in diastole, blood flows passively from the veins into the atria and past the atrioventricular valves into the ventricles.

    • Lindsay M. Biga, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Mat...
    • 2019
  3. Oct 3, 2022 · The cardiac cycle is a series of pressure changes within the heart. These pressure changes result in blood movement through different chambers of the heart and the body as a whole. These pressure changes originate as conductive electrochemical changes within the myocardium that result in the concentric contraction of cardiac muscle.

  4. The period from the start of one heartbeat to the start of the next, including both systole and diastole phases is known as the cardiac cycle. The contraction phase of the heart, during which blood is pumped into circulation is called systole. The relaxation phase of the heart, during which the chambers fill with blood is called diastole.

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