The transport of glucose across the apical plasma membrane of epithelial cells in the small intestine is an example of cotransport. This is the first step in the absorption of glucose from the foods you eat. The transport protein is known as the sodium-glucose cotransporter. Immediately after eating a lot of carbohydrates, the concentration gradient of glucose will favor transport into cells, but as more and more glucose is absorbed, that will not be the case. However, there is almost always a steep concentration gradient favoring the movement of Na+ into cells, because the concentration of Na+ inside of cells is kept very low through the constant action of the sodium-potassium pump (Na+/K+-ATPase, see below). Because transport is coupled, the Na+ concentration gradient can power the movement of glucose uphill against its concentration gradient.