Dr Chris and Dr Xand show how incredible the human body is. The doctors crush a car to reveal the secret of the special fluid which enables your joints to withstand huge amounts of force, and they find out what it's like to be aeroplane cabin crew in Operation Takeover. There are two new patients to meet and First Aid returns - what should you do if someone has swallowed something poisonous? Meanwhile in accident and emergency, there's a gross alert as one patient comes in with a big gash on their head, and another has injured their foot.

There's a big bang in this episode as the doctors reveal the amazing piece of body kit that helps your ears to pop, and in Operation Takeover they find out just how tough it is to be dentists when they have to perform their first ever filling. Dr Xand meets Grace and her amazing assistance dog Scooby and Ouch and About on Call hits the wards to answer patients' medical questions. Meanwhile, in accident and emergency, one patient comes in with a cut head, and another is treated for nonstop nosebleeds.

The doctors take a dip in the sea to reveal how your sensory neurons detect when something is hot or cold, and they find themselves getting stuck in the mud when they join Her Majesty's Coastguard in Operation Takeover. Meet two more new Ouch Patients and find out what to do if someone is unresponsive and not breathing in First Aid. Meanwhile, in accident and emergency, one patient arrives with a broken arm after an accident on a trampoline and another is treated for a busted thumb.

The doctors reveal how big your lungs would be if they were laid out flat and why you need to cough, and in Operation Takeover they find out what it's like to work in the hospital canteen. Dr Chris tries to solve a crime with the help of medical science and a forensics expert, and there are more medical mysteries solved as Ouch & About On Call hits the hospital wards. Meanwhile, in accident and emergency, one patient comes in after falling on her wrist, and another has a rubber stuck in his ear.

The doctors reveal why you need differently shaped teeth to eat your food safely - by wearing some very strange gnashers! And they find out what it's like to be lifeguards in Operation Takeover. We catch up with Ouch Patients Kaden and Maisie, and Dr Chris joins the Royal Airforce to find out what it's like to give emergency medical care to patients in the back of a plane which doubles as a mobile military hospital! Meanwhile, in accident and emergency, one patient arrives after a nasty biking accident, and another has a busted wrist.

The doctors investigate why we need eyebrows, and in Operation Takeover they find out just how tough it is to work in the hospital pharmacy. There are more medical mysteries solved on the wards in Ouch & About on Call, and when Dr Xand spills hot beans on his leg, it's First Aid to the rescue as we find out what to do if someone has a severe burn. Meanwhile, in accident and emergency, one patient has injured their toe in ju-jitsu class, and another hurt her finger doing the crab!

Dr Chris and Dr Xand reveal how your brain enables you to learn new things with the help of three human "samples" from the Cupboard-of-Everything, a giant pile of sand and some water! In Operation Takeover, the twins join the fire service and discover how tough it is to rescue people in a fire. Dr Chris heads to the ophthalmology department to find out how to treat a lazy eye, and we catch up with Ouch Patients Bolu and Millie. Meanwhile, in accident and emergency, one patient has dislocated her ankle and another has injured his knee in the playground.

Dr Chris and Dr Xand find out why blood rushes to your head when you are upside down but does not rush to your feet when you are standing up! Plus they head to the hospital laundry to see if they are up to the job of laundry workers in Operation Takeover. There are also more medical mysteries to be solved in Ouch and About on Call, and they find out what to do if someone has an asthma attack in First Aid. Meanwhile, in accident and emergency, one patient has a rash all over his body and another needs stitches for a cut lip.

Dr Chris and Dr Xand reveal how your bones grow to make you taller, while in Operation Takeover they take on the role of midwives for the day. Plus Dr Chris investigates how scientists are studying people in low oxygen conditions to help seriously ill patients, and we catch up with Ouch Patients Kaden and Maisie. Meanwhile in accident and emergency, one patient has cut their head falling off a wall and another needs help fishing a pencil out of his ear.

Dr Chris and Dr Xand reveal the amazing type of muscles that help you see... and go for a poo! And they find out what it's like to be the hospital hairdresser when they're faced with cutting real people's hair in Operation Takeover. Dr Chris heads into the woods in search of one of the deadliest creatures on earth, and there are more medical questions to be answered in Ouch and About On Call. Meanwhile, in accident and emergency, one patient has a sore eye and another heads to surgery to repair a badly broken wrist.

Dr Chris and Dr Xand reveal how your skull protects your brain, and they are thrown in at the deep end when they find themselves running the reception desk of a busy GP surgery for Operation Takeover. Find out how to deal with a severe allergic reaction in First Aid, and there is a catch-up with Ouch patients Millie and Bolu. Meanwhile, over in accident and emergency, one patient has twisted their leg falling at a trampoline park, while another has diamonds stuck up his nose.

Dr Chris makes Dr Xand cry to demonstrate how your amazing body makes different types of tears to protect your eyes in different ways, and in Operation Takeover they discover just how dangerous it can be out at sea when they join the lifeboat service. Dr Xand investigates how important our facial expressions are, and the hospital wards are bursting with more medical questions in Ouch and About on Call. Over in accident and emergency, one patient has cut her hand with a craft knife and another needs his gnashers fixing after falling at a skate park.

In the last episode of the series, the doctors have picked out some of their favourite moments - get ready to see just how strong your tendons really are and discover who the better pilot is when Dr Chris and Dr Xand join the air ambulance in Operation Takeover. Find out how to help someone who's been drowning in First Aid, and catch up with our four Ouch Patients for one last time. Meanwhile, in accident and emergency, some of our favourites are back too - arriving by helicopter is Jamie with a sore neck and Bella Rose, who's got a sore hip after busting some moves on the dance floor.

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