the concentrationgradient of one of the molecules is used to move the other molecule againstitsconcentration gradient
glucose is absorbed into the bloodstream in the small intestine
in the ileum, the concentration of glucose is too low for glucose to diffuse into the blood. so it's absorbed from the lumen of the ileum by co-transport
sodium ions are activelytransported out of the ileum epithelial cells into the blood by the sodiumpotassiumpump, creating a concentrationgradient between the lumen of the ileum and the epithelial cells
2. this causes sodium ions to diffuse out of the lumen of the ileum into the epithelial cell, down the concentration gradient. done by the sodium glucose co-transporter proteins
3. the co-transporter carries glucose into the cell along with sodium, increasing the concentration of glucose inside the cell
4. glucose diffuses out of the cell, into the blood, by facilitated diffusion