circulation
- Blood Pressure Explained: What the Two Numbers Mean
Blood pressure is the force of blood against artery walls, written as systolic over diastolic in mmHg. Learn what each number measures and how readings are rated. - How the Heart Works: Chambers, Valves, and the Cardiac Cycle
The heart is a four-chambered muscular pump. Learn how blood flows through its chambers and valves, how it keeps its rhythm, and what a heartbeat actually is.