Michael Mosley spends the day as an exhibit at the Science Museum in London, where he swallows a tiny camera which transmits live pictures of his body digesting food.

He has drunk four litres of laxative in preparation for the experiment - to help clear the way for the camera. Once it's inside his body, Michael has no control over the miniature camera, which has been placed inside a small pill.

He discovers pools of concentrated acid and metres of writhing tubing which is home to its own ecosystem.

Michael Mosley presents Guts: The Strange and Mysterious World of the Human Stomach on BBC Four at 21:00 BST on Thursday 12 July or online afterwards at the above link (UK only).