The transport of one substance coupled with the transport
of another substance across a plasma membrane in the
same direction through the same protein carrier.
Does co-transport use ATP?
Does NOT use ATP directly.
Energy to do this comes from the use of the gradient of the
1st solute’s concentration to force the 2nd solute AGAINST its
concentration gradient.
What is step one of the absorption of glucose in the Small Intestine?
The sodium potassium pump actively transports 3 sodium ions out of the intestinal epithelial cell and into the blood in exchange for 2 potassium ions. This process requires energy in the form of ATP.
What is step 2?
This maintains a lower concentration of sodium ions inside the intestinal epithelial cell as compared to the lumen of the small intestine.
What is step 3?
Sodium ions in the lumen of the small intestine move down its concentration gradient into the intestinal epithelial cell by facilitated diffusion. This movement is coupled with the active uptake of glucose through the Na+/glucose symport protein (a co-transport carrier protein).
What is step 4?
This establishes a higher concentration of glucose inside the intestinal epithelial cell as compared to the bloodstream.
What is step 5?
Glucose molecules move down its concentration gradient from inside the intestinal epithelial cell into the bloodstream by facilitated diffusion.
