Learn: Cardiac Cycle, Cardiac Output and Blood Pressure

Welcome!You've already learned about The Heart and Blood Vessels, including the structure and function of the heart. Today, we'll build on that by exploring the cardiac cycle, cardiac output, and how blood pressure is regulated.

What is the Cardiac Cycle?The cardiac cycle describes the sequence of events in one heartbeat. It includes the contraction and relaxation of heart chambers to pump blood. This cycle ensures oxygenated and deoxygenated blood are efficiently transported around the body.

Phases of the Cardiac CycleThe cardiac cycle has three main phases: atrial systole (atria contract), ventricular systole (ventricles contract), and diastole (relaxation phase). During diastole, blood flows into the heart, preparing it for the next beat.

What is Cardiac Output?Cardiac output is the volume of blood pumped by the heart per minute. It’s calculated as heart rate (beats per minute) multiplied by stroke volume (amount of blood pumped per beat). This measure indicates how effectively the heart meets the body’s needs.

Blood PressureBlood pressure is the force exerted by blood on the walls of blood vessels. It is measured in two values: systolic pressure (during ventricular contraction) and diastolic pressure (during relaxation). Normal blood pressure is about 120/80 mmHg.

Regulation of Blood PressureThe body regulates blood pressure through mechanisms such as vasodilation (widening of vessels) and vasoconstriction (narrowing of vessels). These changes control blood flow and pressure to maintain homeostasis.

Review Time!Great work! You've learned about the cardiac cycle, cardiac output, and blood pressure. Let’s review everything with a few questions to test your understanding.