Find out what really happens to you when you get bitten by Zombie. Dr Chris and Dr Xand Van Tulleken from Operation Ouch explain the science behind .\r<br>\r<br>Dr Chris gets an ultrasound on his bladder to show what happens when you have a wee! Watch this clip from Operation Ouch! Watch more great Operation .\r<br>\r<br>Chris and Xand go back in time to find out how to fix a broken bone in a World War 1 trench. Watch the full episode on Friday August 8th on CBBC and CBBCHD .
