What are 3 adaptations that increase the surface area in the small intestine?

The small intestine increases its surface area through three key adaptations: villi, microvilli, and circular folds (plicae circulares). Villi are finger-like projections that extend into the intestinal lumen, while microvilli are even smaller projections on the epithelial cells of the villi, forming a brush border. Circular folds are large, permanent folds of the intestinal wall that slow down the movement of chyme, allowing for more efficient nutrient absorption. Together, these adaptations enhance the intestine's ability to absorb nutrients effectively.