Glucose absorption. Illustration showing glucose absorption and the role of tight junctions (occluding junctions) in intestinal epithelial cells. At top is the lumen of the intestine (gut) where food digestion has produced the simple sugar glucose (green). Two types of channels transport glucose from the intestinal lumen to the bloodstream (red, bottom). Active glucose channels top) bring the glucose inside the epithelial cell (orange). Passive glucose channels on the internal side of the membrane carry the glucose into the blood. The tight junctions (centre left, ridged) keep the glucose channels separate. For this artwork with labels, see C023/8825.