The human body is incredibly resilient. When you donate a pint of blood, you lose about 3.5 trillion red blood cells, but your body quickly replaces them. You can even lose large chunks of vital organs and live. For example, people can live relatively normal lives with just half a brain). Other organs can be removed in their entirety without having too much impact on your life.

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How the heart actually pumps blood
For most of history, scientists weren’t quite sure why our hearts were beating or even what purpose they served. Eventually, we realized that these thumping organs serve the vital task of pumping clean blood throughout the body. But how? Edmond Hui investigates how it all works by taking a closer look at the heart’s highly efficient ventricle system.

What does the liver do?
There’s a factory inside you that weighs about 1.4 kilograms and runs for 24 hours a day. It’s your liver: the heaviest organ in your body, which simultaneously acts as a storehouse, a manufacturing hub, and a processing plant. Emma Bryce gives a crash course on the liver and how it helps keep us alive.

How your digestive system works
Constantly churning inside of you, the digestive system performs a daily marvel: it transforms your food into the vital nutrients that sustain your body and ensure your survival. Emma Bryce traces food’s nine-meter-long, 40-hour journey through the remarkable digestive tract.

How do the lungs work?
When you breathe, you transport oxygen to the body’s cells to keep them working, while also clearing your system of the carbon dioxide that this work generates. How do we accomplish this crucial and complex task without even thinking about it? Emma Bryce takes us into the lungs to investigate how they help keep us alive.

What does the pancreas do?
Beneath your ribs, you’ll find, among other things, the pancreas -- an organ that works a lot like a personal health coach. Emma Bryce explains how this organ controls your sugar levels and produces a special juice that releases the nutrients from your food to help keep you in the best possible shape.

Oxygen’s surprisingly complex journey through your body
Oxygen forms about 21% of the air around us. In your body, oxygen forms a vital role in the production of energy in most cells. But if gases can only efficiently diffuse across tiny distances, how does oxygen reach the cells deep inside your body? Enda Butler tracks the surprisingly complex journey of oxygen through your body.