Into the Depths of Jenna's Digestive System is the 21st episode of Season 31 on Disney and the 35th on Nickelodeon. Now it's Jenna's turn to have a problem. Jenna eats something that gives her terrible indigestion, so Phineas and friends must go into Jenna's digestive system to help her out. Doofenshmirtz is off on a vacation, which Perry is unaware about.