Learn: Cardiac Cycle, Cardiac Output, and Blood Pressure

Welcome!You've already learned about the heart and blood vessels, so let's build on that foundation. Today, we'll explore how the heart works during the cardiac cycle, how cardiac output is calculated, and how blood pressure is regulated.

What is the Cardiac Cycle?The cardiac cycle refers to all the events that occur during one heartbeat. It includes the contraction (systole) and relaxation (diastole) of the heart chambers. This cycle ensures blood flows efficiently through the heart, lungs, and body.

Phases of the Cardiac CycleThere are three main phases:Atrial systole: The atria contract, pushing blood into the ventricles.Ventricular systole: The ventricles contract, pumping blood into the arteries.Diastole: The heart relaxes, allowing the chambers to fill with blood.

What is Cardiac Output?Cardiac output is the amount of blood the heart pumps in one minute. It depends on two factors:Heart rate: The number of beats per minute.Stroke volume: The volume of blood ejected by each ventricle during a single beat.The formula is: Cardiac Output = Heart Rate × Stroke Volume.

What is Blood Pressure?Blood pressure is the force exerted by blood against the walls of blood vessels. It is measured in two values:Systolic pressure: The pressure during ventricular contraction.Diastolic pressure: The pressure during relaxation.Blood pressure is expressed as systolic/diastolic (e.g., 120/80 mmHg).

Factors Affecting Blood PressureBlood pressure is influenced by:Cardiac output: Higher cardiac output increases pressure.Peripheral resistance: Narrow or less elastic arteries increase resistance and pressure.Blood volume: More blood volume increases pressure.

Review Time!Fantastic work! You've covered the cardiac cycle, cardiac output, and blood pressure. Now let's test your understanding with a few final questions.