peristalsis
noun [ U ] biology specialized uk/ˌper.ɪˈstæl.sɪs/ us/ˌper.ɪˈstɑːl.sɪs/
蠕动（消化道肌肉壁所作的反复运动，即张紧而后舒张，推动食物和废物通过身体）
the repeated movements made by the muscle walls in the digestive tract tightening and then relaxing that push food and waste through the body