What structure allows molecules to absorb in the small intestine?

Villi: The folds form numerous tiny projections which stick out into the open space inside your small intestine (or lumen), and are covered with cells that help absorb nutrients from the food that passes through. Microvilli: The cells on the villi are packed full of tiny hairlike structures called microvilli. The function of the plicae circulares, the villi, and the microvilli is to increase the amount of surface area available for the absorption of nutrients. Each villus transports nutrients to a network of capillaries and fine lymphatic vessels called lacteals close to its surface.

The formula is (nh4)2co3