Question

What is the reason, that digested molecules get absorbed by small intestine? Not by other parts

of digestive tract?​

Answer 1

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This is because small intestine is designed for absorption of digested molecules. They contain small finger-like projections called villi which absorb the digested molecules.

As these villi are not present in any other part of the digestive tract, so absorption cannot occur anywhere else. Moreover, digestion is completed in the small intestine, so how can any other part absorb digested molecules before they are even digested?

Point to note:- Villi are present in large intestine also, but there they are designed for absorption of water from undigested food, since the digested molecules were already absorbed by the small intestine.