How do We Burn Calories? | Earth Science

This is the amount of crisps that a very greedy person might eat. It might be the amount of crisps I might eat. Would this be a long movie? Can I easily see this? Yeah, I mean we've all we've all done that. Okay, so now we have the lovely liquid oxygen. You can see there. Ready? I'll stand back a little bit. I'm not going to eat crisps for the rest of the day. No. Maybe not even tomorrow. No. Then I'll be right back to business as usual. That was spectacular. We've completely melted the aluminium baking tray. Even as a scientist I am astounded at the energy contained in just 400 calories and most of us put at least five times that much energy into our bodies every single day. But we obviously don't have roaring fires burning in our bellies. Our body has to release all that energy in a very different way. To show you how I've come back to medical school. What we're about to see is something truly fascinating but not for the faint-hearted. Anatomist Claire Smith is showing me a real human digestive system. It's a vast alien looking mass of tubes and this is the stomach. I guess I thought it would be a really big bag if I think of how much I feel I can stuff into it. So it is capable of stretching so if you've eaten a large meal with a couple of glasses of water it is able to stretch. Okay. It typically holds about one litre. And then from the stomach you then have a region here where you're then going into the small intestines and all of these that you can see here this is all small intestines. This is where the action happens as it were. So this is the small intestine running along here. This is our special structure called the mesentery which delivers all the arteries and the veins to the small intestines. So the arteries are bringing nice fresh oxygen to the intestines and the veins are taking our calories back to be used around the rest of the body. The mesentery, I really like that. If you hold it up to the light enough you can see the blood vessels. Despite its extensive blood supply and enormous length the gut still takes hours to break food down into a form that it can be burned by the rest of our body. There's on average about six metres of small intestines. Six metres? So three of me and a bit. And a bit. But as you can tell it's all curled up in a way that doesn't get tangled. I guess kind of amazed at how it all works. It's always amazing. Every time you look at different parts of the anatomy and you understand it is always fascinating.