这种维生素通过小肠壁被吸收。This vitamin is absorbed through the walls of the small intestine.肠肽酶是由小肠壁的腺体分泌的.Erepsin is secreted by glands in the wall of the small intestine.肠壁薄,几乎是透明的,这可能是因绒毛萎缩.The wall is thin and almost transparent...

“肠壁”的英语可以翻译为：intestinal wall ...