Digestive system
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Owen Harper's digestive system shut down following his death and partial resurrection. As a result, he could not eat or drink. (TV: Dead Man Walking)
Raxacoricofallapatorians had varying digestive systems according to family: A Slitheen noted the Hazrateen to have superior tastes which allowed them to enjoy the richest of foods, while the Blathereen were content with lower grade products. (AUDIO: The Taste of Death)