Circulatory System
Explore the heart, blood vessels, blood, and the pathways that keep oxygen, nutrients, hormones, and waste moving throughout the body.
Explore the cardiovascular system
Use the interactive cardiovascular guide to explore the heart, blood vessels, circulation, and blood.
Open Innerbody guide →Explore the external heart
Rotate and inspect the external anatomy of the human heart in three dimensions.
Open model source →Learn it step by step.
Start with how blood moves through the body, then move into the heart, blood vessels, blood itself, and the circulatory loops that connect everything together.
The Circulatory System
Build the foundation. Learn what the cardiovascular system contains, what it transports, and how the heart and vessels work together to keep blood moving.
The Heart
Explore the four chambers, valves, great vessels, and the heart's role as a double pump.
Blood Vessels
Learn the differences between arteries, capillaries, veins, arterioles, and venules.
Blood
Discover plasma, red blood cells, white blood cells, platelets, and what blood transports.
Circulatory Loops
Follow pulmonary and systemic circulation and learn how blood completes its journey through the body.
Test Your Knowledge
Finished all five lessons? Take the final Circulatory System assessment and see how much you remember.
Follow the blood.
The easiest way to understand the cardiovascular system is to follow one continuous journey: heart → lungs → heart → body → heart.
The heart
Learn how the heart generates the pressure that drives circulation.
The vessels
See how blood travels through arteries, capillaries, and veins.
The blood
Understand what blood carries and the cells that make up its cellular component.