Flexes Its Muscles

Flexes its Muscles is the 15th episode in the series.

Appearances

 * Ralphie Tennelli
 * Keesha Franklin
 * R.U. Humerus

Notes & trivia

 * R.U's name is a joke on the arm's main bones.
 * This is the only human body episode the kids don't go into a body for.
 * Instead, they use an X-Ray like machine.