Study Question Three

• Q3. List and describe each step in the cardiac cycle, and how this relates to the flow of electrical signals through the cardiac conduction system.
• List and describe each step in the cardiac cycle, and how this relates to the flow of electrical signals through the cardiac conduction system.

  The cardiac cycle starts with atrial systole, as it occurs at the end of the ventricular filling phase. The sinoatrial node, the heart's natural pacemaker, generates an action potential that spreads to both atria and causes them to depolarize or contract.
• List and describe each step in the cardiac cycle, and how this relates to the flow of electrical signals through the cardiac conduction system.

  Secondly, ventricular systole. When pressure is high, semilunar valves will open. The electrical impulse has traveled from sinoatrial node through internodal pathway to atrioventricular node. This AV node conduct the action potential slowly, giving the ventricles time to fill with blood, and the electrical impulse to travel through the AV bundle, AV bundle branches, to the Purkinje fibers that spread the impulse rapidly for contraction.
• List and describe each step in the cardiac cycle, and how this relates to the flow of electrical signals through the cardiac conduction system.

  Third, ventricular ejection, the end of ventricular systole. As pressure builds up, the semilunar valves open, ejecting blood out of the ventricles. The purkinje fibers help propagate the action potential through the ventricular myocardium, coordinating the contraction.
• List and describe each step in the cardiac cycle, and how this relates to the flow of electrical signals through the cardiac conduction system.

  Fourth, ventricular diastole, which occurs when the ventricles relax and the pressure drops, so the semilunar valves close back up. During this phase, the ventricles are repolarized since most of the action potentials have passed.
• List and describe each step in the cardiac cycle, and how this relates to the flow of electrical signals through the cardiac conduction system.

  Fifth, ventricular diastole or ventricular filling. The atrioventricular valves open, allowing blood to flow from the atria to the ventricles known as passive filling. During this phase, the heart is electrically quiet until the next cycle where the sinoatrial node will trigger the entire cycle once again.