Co-transport:Glucose

• How is glucose absorbed into the mammalian ileum?

  co-transport
• Where is glucose absorbed into?

  The bloodstream in the small intestine
• What is the ileum?

  the final part of the small intestine
• What is the conc of glucose like in the ileum?

  Too low for glucose to diffuse out of the blood

  • so glucose is absorbed from the LUMEN of the ILEUM by active transport
• Glucose enters the ileum epithelium with what?

  Sodium ions
• Explain co-transport with glucose and sodium step 1?

  Sodium ions are actively transported out of the ileum epithelial cells into the blood by the sodium-potassium pump-

  this creates a concentration gradient- higher conc of Na+ ions in lumen of ileum than inside the cell
• Explain co-transport with glucose and sodium step 2?


  This conc gradient causes sodium ions to diffuse from lumen of ileum into epithelial cell, DOWN their CONC GRADIENT, via sodium-glucose co-transporter PROTEINS
• Explain co-transport with glucose and sodium step3?

  the co-transporter carries glucose into the cell with the sodium.

  as a result thhe conc of glucose inside the cell increases
• Explain co-transport with glucose and sodium step 4- FINAL STEP?

  Glucose diffuses out of the cell, into the blood, down its conc gradient through a protein channel, by facilitated diffusion