CO-TRANSPORT

• WHEN IS CO-TRANSPORT REQUIRED?

  to absorb glucose from lumen to the gut, a higher concentration of glucose in the lumen than epithelial cells is required

  -> more glucose in epithelial cells so co-transport/ active transport required
• EXAMPLE OF CO-TRANSPORT?

  glucose and sodium ions in ileum
• PROCESS OF CO-TRANSPORT OF GLUCOSE AND SODIUM IONS IN ILEUM?

  1. Na+ ions actively transported out of epithelial cells into the blood
  2. Reduces Na+ ion concentration in epithelial cells
  3. Na+ ions diffuse from lumen down concentration gradient into epithelial cell
  4. Protein the Na+ ions diffuse through is a co-transported protein (either glucose/ AAs attach and are transported into epithelial cell against concentration gradient)
  5. Glucose then moves by facilitated diffusion from epithelial cells to the blood