AP BIOLOGY

Detailed explanation-1: -The lining of the small intestinal mucosa is very highly specialized for maximizing digestion and absorption of nutrients. The lining is highly folded to form microscopic finger-like projections called villi which increase the surface area to help with absorption.

Detailed explanation-2: -Mucosa. The walls of the small intestine are lined with a dense mucosa with many glands that both secrete and absorb. In the jejunum and the ileum, the mucosa secretes small amounts of digestive enzymes and lubricating mucus while absorbing nutrients from your food.

Detailed explanation-3: -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.

Detailed explanation-4: -Tiny hair-like projections that line the inside of the small intestine. They contain blood vessels and help absorb nutrients.

Detailed explanation-5: -In a process called active transport, specialized intestinal cells of the villi allow the passage of B-12, iron and calcium into the bloodstream.