Final answer:
The fingerlike projections that increase the surface area for absorption in the small intestine are called villi, and the even smaller projections on the absorptive cells are known as microvilli.
Step-by-step explanation:
The fingerlike projections of the small intestine that increase the absorptive surface area are called villi. These structures play a crucial role in nutrient absorption. The inside of each villus is rich in blood vessels and lymphatic vessels, enabling the rapid uptake of nutrients into the bloodstream. In addition to villi, the absorptive cells of the small intestine have even smaller projections called microvilli, which further increase the surface area available for nutrient absorption. The microvilli form what is known as the brush border, which is coated with digestive enzymes and facilitates the final stages of digestion.