THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The numerous permanent circular folds of mucous membrane found in the small intestine especially in the lower part of the duodenum and the jejunum are called plicae circulares. They are covered with small finger-like projections called villi which is covered with microvilli.

Detailed explanation-2: -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-3: -In addition, the cells of the villi are covered with even smaller hairlike structures called microvilli. Microvilli projections are smaller than villi. Their job is to also increase the surface area so each individual villi can absorb the maximum amount of nutrients.

Detailed explanation-4: -Answer and Explanation: Villi, microvilli, and circular folds (plicae circulares) are structures in the wall of the small intestine that enhance the digestive process particularly the absorption of nutrients.