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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.
Secretion- release of digestive enzymes and other substances into the lumen (space inside the tube) c. Digestion- breakdown of food into particles, then into nutrient molecules small enough to be absorbed. d. Absorption- passage of digested nutrients and fluid across the tube wall and into blood or lymph.