Co- transport

• Movement across membranes by co-transport involves the absorption of sodium ions and glucose by cells lining the mammalian ileum.
• Sodium ions are actively transported out of epithelial cells lining the ileum, into the blood, by the sodium-potassium pump.
• Creating a concentration gradient of sodium involves having a higher concentration of sodium in the lumen than in the epithelial cell.
• Sodium ions and glucose move by facilitated diffusion into the epithelial cell from the lumen, via a co-transporter protein.
• Creating a concentration gradient of glucose involves having a higher concentration of glucose in the epithelial cell than in the blood.
• Glucose moves out of the cell into the blood by facilitated diffusion through a protein channel.