Human: The World Within

An introduction into the amazing functions of the human body's immune system.

An introduction to the amazing functions of the human body's digestive system. Our continued survival as individuals and as a species requires energy. And we get that by extracting nutrients from the food we eat. Our digestive system has the job of refining everything we eat into raw power.

Through the worlds of a religious faster, an ultra-marathon runner, a farmer and a young girl beating allergies, go deep into the world of the human gut, which processes the fuel our bodies need to keep going.

The microbiome is the cutting edge of gut science. It's an ecosystem that's made up of trillions of bacteria that instead of making us sick, actually have a big hand in keeping us healthy. When this population of microbes is thriving and in check, it does wonders for the body.

At the center of the circulatory system is the heart, which works with the lungs to constantly keep the body supplied with freshly oxygenated blood. Every time we breathe in, we are infusing blood flowing through tiny vessels in the lungs with oxygen that can be carried to the furthest reaches of our anatomy.

Staying active and on the move is crucial to our health for a lot of reasons. But it's especially important for the circulatory system to function properly. In fact, our bodies are actually designed so that blood circulation depends on us being in semi-constant motion.

Dive into the world of an ice climber, a bus driver, a woman in labor and a senior dance club to show how the human heart and the circulatory system power our physical and emotional lives and create the pulsing rhythm of our world.

It's the circulatory system that provides every cell in our body with the juice they need to function. The human body can only survive about three minutes without oxygen, and it's this incredibly vast network that is responsible for delivering this life-giving gas to all 40 trillion cells in the body.

Go on a journey with parents who are preparing for babies to see how our bodies create and sustain new life. Through their stories, we learn about what is fundamentally shared and absolutely unique about the experience of birth.