Described herein are peptides, compositions, and related methods for treating upper gastrointestinal disorders and conditions (e.g., dyspepsia, gastroparesis, post-operative gastric ileus, a functional esophageal disorder, a functional gastroduodenal disorder, gastroesophageal reflux disease (GERD), or a duodenal or stomach ulcer) as well as other conditions and disorders that are described herein.