cardiovascular

The heart beats more than 100,000 times per day without a single conscious command, regulated by an electrical system so precise that it can be measured from electrodes on the skin. Here is how that system works, from the first spark in the SA node to the pressure wave that reaches your fingertips.

How the human heart pumps blood: chambers, valves, electrical conduction, cardiac cycle, and the most important diseases and treatments.

Your heart beats about 100,000 times a day without a single conscious thought. Here's the remarkable engineering behind it.

ISS research reveals how weightlessness causes fluid shifts, cardiac deconditioning, and blood flow changes—insights applicable to heart disease treatment on Earth.