Final answer:
The microscopic, finger-shaped projections in the small intestine that contain blood capillaries and lymph are called villi, which increase the surface area for nutrient absorption.
Step-by-step explanation:
The microscopic, finger-shaped projections that contain blood capillaries and lymph are called villi. These structures are found within the circular folds of the small intestine's lining. Each villus is composed of muscle, connective tissue, a capillary bed, and a lymphatic capillary known as a lacteal. The absorptive cells that line the villi have even smaller projections called microvilli, which further increase the surface area available for nutrient absorption. The microvilli create a structure known as the brush border which, equipped with enzymes, aids in the final digestion of carbohydrates and proteins.