The cardiac cycle: one rule runs every heartbeat (in 3D)

What actually makes the sounds of your heartbeat? This 3D walk through the cardiac cycle shows how one rule - pressure decides everything - runs the whole cycle, why 70–80% of ventricular filling happens before the atria ever contract, and how to read the classic pressure-time graph on sight. Chapters: 00:00 The sound you've heard your whole life 00:24 One rule runs everything 01:03 A tour of the four chambers 01:38 Diastole - filling without pumping 02:50 Ventricular systole - lub and dub 04:03 The same heartbeat, as a graph 05:19 What you're actually hearing Credits: Anatomy models: Z-Anatomy (CC BY-SA 4.0), based on BodyParts3D — z-anatomy.com Heartbeat sound: Benboncan (CC BY 3.0), via Wikimedia Commons / Freesound