The doctors reveal the incredible muscles that help you see as well as go to the toilet. Plus, they find out if they make the cut as hospital hairdressers in Operation Takeover.

The doctors look at how the skull protects the brain, and find themselves in over their heads running a busy reception desk for a GP surgery in Operation Takeover.

The doctors demonstrate the different types of tears the body makes in order to protect the eyes, and they find out how dangerous the sea can be when they join the Lifeboat Service in Operation Takeover.

In the final episode for the season, the doctors choose some of their favourite moments to reminisce upon, and hope to prove once and for all who the better pilot is when they join the air ambulance service in Operation Takeover.

Dr Chris and Dr Xand Van Tulleken investigate what mental health is and why things can sometimes go wrong.

The doctors demonstrate how genes make a person; a new doctor joins the team; Dr Ronx heads behind the scenes of Homerton Hospital.

The doctors demonstrate how strong a human skeleton is; meet callisthenics world champion Simone Ming; Dr Ronx heads out with paramedics.

The doctors take a look at why people are squeamish and tackle medical mysteries on the wards; Emille stops by the emergency room with a broken arm from a bike accident.

Dr Xand investigate how blood clots, and Dr Ronx take a look at how echolocation assists visually impaired patients.

The doctors investigate the colour of poo; Dr Xand discovers the breathing skills necessary to free dive; Ouch Patients Rio and Emilia reflect on their experiences.

The doctors look at the three bones in the nose called turbinates; how scientists are growing a brain; how to trick taste buds; plus more Ouch Awards nominees.