The Cardiac Cycle: The Cardiac Cycle

The Cardiac Cycle The cardiac cycle is the sequence of events that occur in the heart during one heart beat. It is how the heart operates, and what exactly happens when it contracts and relaxes. The heart is equipped with four chambers and one-way valves that work with precision to pump blood to and from the body. The heart regulates blood volume to support efficient circulation to the cells, tissues, organs, and systems. It provides oxygen and nutrients to the bodies tissue while also removing metabolic waste from cells to disposal sites. It is ultimately responsible for many homeostatic actives that keep us alive and well. It beats roughly seventy-five beats per minute, which is less than one beat per second. During the single beat, the heart goes through a series of steps that is ultimately called the cardiac cycle. There are two phases that take place during this …show more content…
This occurs when the ventricles are almost full the atria contracts, pumping more blood into the ventricles. The contraction completes ventricular filling, causing the pressure and volume in the ventricles to further increase. Following Atrial Systole is Ventricular Systole. This is when the ventricles contract, forcing blood back up towards the atria. When the pressure in the ventricles exceeds that in the atria it snaps the AV valves shut, causing the first heart sound, “lub.” The semilunar valves remain closed, trapping all the blood in the heart within the ventricles. It 's at this point in the cycle the heart contains the maximum amount of blood, known as the end-diastolic volume. The heart is going through Isovolumic Ventricular Contraction. This is when the ventricles are contracting, but the valves are closed. During this phase of the cardiac cycle, the pressure in both the ventricles are increasing, but the volume stays the same. When the pressure in the ventricle exceeds that of the aorta or arteries, the semilunar valves will