Final answer:
The small intestine is where the digestion of nutrients is completed and absorption takes place. The first organ that receives the absorbed nutrients in the blood is the liver.
Step-by-step explanation:
The small intestine is the organ where the digestion of protein, fats, and carbohydrates is completed. It is a long tube-like organ with a highly folded surface containing finger-like projections called villi. The villi and microvilli, with their many folds, increase the surface area of the intestine and increase the absorption efficiency of the nutrients. After the nutrients are absorbed from the digested food, they enter the bloodstream. The first organ that receives this nutrient-rich blood is the liver, through the hepatic portal vein.