The Cardiac Cycle :: Papers

The Cardiac Cycle The cardiac cycle is the while of events that occur when the heart beats. thither ar two phases of this cycle * Diastole - Ventricles are relaxed. * Systole - Ventricles contract. During the diastole phase the atria and heart ventricles are relaxed and the auriculoventricular valves are open. De-oxygenated crinkle from the superior and substandard vena cava flows into the right atrium. The open atrioventricular valves allow seam to get in through to the ventricles. The SA node contracts triggering the atria to contract. The right atrium empties its contents into the right ventricle. The tricuspid valve prevents the blood from flowing stake into the right atrium. During the systole phase the right ventricle receives impulses from the Purkinje fibers and contracts. The atrioventricular valves close and the semilunar valves open. The de-oxygenated blood is pumped into the pneumonic artery. The pulmonary valve prevents the bloo d from flowing back into the right ventricle. The pulmonary artery carries the blood to the lungs. There the blood picks up oxygen and is returned to the left-hand(a) atrium of the heart by the pulmonary veins. In the next diastole period, the semilunar valves close and the atrioventricular valves open. Blood from the pulmonary veins fills the left atrium. (Blood from the vena cava is also filling the right atrium.) The SA node contracts once again triggering the atria to contract. The left atrium empties its contents into the left ventricle. The mitral valve prevents the oxygenated blood from flowing back into the left atrium. During the systole phase the atrioventricular valves close and the semilunar valves open. The left ventricle receives impulses from the Purkinje fibers and contracts. Oxygenated blood is pumped into the aorta. The aortic valve prevents the oxygenated blood from flowing back into the left ventricle. The aorta branches out to provide oxygenated blood to all parts of the body. The oxygen blue blood is returned to the heart via the vena cava. Atrial systole Ventricular systole Ventricular Diastole