The Cardiac Cycle Quiz

Cardiac Cycle and ECG

• The Bundle of His is responsible for the depolarization of the ventricles.
• The outermost layer of the heart wall is called the epicardium.
• The innermost lining of the heart muscle is called the endocardium.
• The formula for calculating cardiac output is Cardiac Output = Heart Rate x Stroke Volume.
• The mechanical factor that affects stroke volume is preload.
• The P wave on an ECG represents atrial depolarization.
• The QRS complex on an ECG represents ventricular depolarization.
• The T wave on an ECG represents ventricular repolarization.
• The interval measured from the start of the P wave to the start of the Q wave on an ECG is called the PR interval.
• The interval measured from the end of the S wave to the start of the T wave on an ECG is called the ST segment.

Phases of the Cardiac Cycle

• During the atrial contraction phase, the atria contract and push blood out of the atria and into the ventricles.
• The purpose of the Isovolumetric Ventricular Contraction phase is to allow the ventricles to contract and build pressure without changing volume.
• The SL valves open during the rapid ejection phase.
• Residual volume in the context of the cardiac cycle is the volume of blood left in the ventricles after systole.
• The closure of the SL valves during the cardiac cycle is caused by the increase in ventricular pressure.
• The phase of the cardiac cycle that occurs between the closure of the SL valves and the re-opening of the AV valves is the isovolumetric relaxation phase.
• The purpose of measuring blood flow, pressure changes, and blood volume throughout the cardiac cycle is to understand the cardiac function and identify any abnormalities.

Cardiac Cycle Events

• The onset of ventricular systole during the cardiac cycle is marked by the QRS complex.
• A complete heartbeat or pumping cycle is called a cardiac cycle.
• The cardiac cycle is broken down into 8 phases or steps.