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The small intestine is a long, highly convoluted tube in the digestive system that absorbs about 90% of the nutrients from the food we eat. It is given the name âsmall intestineâ because it is only 1 inch in diameter, making it less than half the diameter of the large intestine.
Digestion is the process of breaking down organic molecules into pieces small enough to cross the cell membranes of the digestive tract. The process of absorption allows the membranes to be crossed and pieces to enter the blood. Eventually they are delivered to cells where they can be used.