Mr. Heart is a Valentine's Day-themed episode of Mr. Young.
Adam finds out Echo has a cold (caught from Slab) on Valentine's Day. He tries to go ahead and build a shrink ray to enter Echo's body to get rid of the virus. Unfortunately, Derby mistakes the shrink ray for a camera and enters Echo's body as well. Derby, not knowing anything about the human body, keeps making everything worse for Adam. The duo get stuck in Echo's stomach, and then end up in the throat after Derby pops a gas buddle, allowing Echo to burp. They run into the source of the virus, and all of the germ cells look exactly like Slab. after they try to get out of Echo's body, by traveling thought the ears, the heart, and the body system, after Echo came back from the nurses office, Adam and Derby got back to normal size, but Unfortunately, they got shrunk again (including Echo), and at the end, they ending up into Slab's body
When Adam tries to ask Echo out for dinner, the sick Echo sneezes on Adam. Weirdly, Adam didn't get the Slab virus and somehow didn't get infected. Probably, Adam had some scientific medicine to cure himself. However, we can expect that he didn't because he made a shrink machine to shrink Adam and Derby in order to cure Echo from the inside.
This is a experience of learning about the human body.
This episode helped lots of children
Error: if Adam, Derby, and Echo are eated by Slab, how did they get out in the next episode, they could of get digested already