How is glucose primarily absorbed in the intestinal epithelial cells?

Glucose is primarily absorbed in the intestinal epithelial cells through Na+ dependent cotransport, which is also known as secondary active transport. This process involves the use of a sodium-glucose cotransporter (SGLT) that allows glucose to enter the cells along with sodium ions.

In the intestinal lumen, when sodium ions are actively transported out of the epithelial cells into the extracellular fluid, it creates a concentration gradient. This gradient facilitates the movement of sodium back into the cells, which, through the cotransporter, also encourages glucose to enter by utilizing the energy derived from the movement of sodium down its concentration gradient. This method of absorption is efficient and ensures that glucose is effectively taken up from the digestive tract following a meal.

Additionally, this process is critical because glucose is a vital energy source for the body, and the SGLT mechanism allows for its rapid and efficient absorption while simultaneously managing sodium levels within the intestinal cells.