Describe how glucose is transported into epithelial cells in the ileum

Na+ ions are actively transported out of the epithelial cell into the blood by an Na+ pump. This requires ATP. This establishes a concentration gradient of Na+, with a high Na+ concentration in the ileum and a low Na+ concentration inside the epithelial cell. Na+ ions therefore move down the concentration gradient, from the ileum into the epithelial cell. To do this, the Na+ ions bind to an Na+/glucose pump. This causes the Na+/glucose pump to change shape/conformation, allowing a glucose molecule to also bind to the Na+/glucose pump. Together, the Na+ and glucose molecule are transported into the epithelial cell by the Na+/glucose pump, down the concentration gradient. This is called co-transport. The glucose molecule then moves down its concentration gradient from the epithelial cell into the blood by facilitated diffusion through a special carrier protein.