Final answer:
The small intestine is the primary organ responsible for the absorption of the products of digestion. It has a highly folded surface with villi and microvilli that increase its surface area for efficient nutrient absorption. Absorbed nutrients are carried into the hepatic portal vein and distributed throughout the body.
Step-by-step explanation:
The primary organ responsible for absorption of the products of digestion is the small intestine. It is a long tube-like organ with a highly folded surface containing finger-like projections called villi. The villi and microvilli increase the surface area of the intestine, allowing for efficient absorption of nutrients from digested food into the bloodstream. Absorbed nutrients are then carried into the hepatic portal vein and distributed to the rest of the body.