Final answer:
Ingested nutrients spend approximately 4 hours in the small intestine as chemical digestion and absorption are completed.
Step-by-step explanation:
The small intestine is responsible for the completion of chemical digestion and absorption of ingested nutrients. It takes approximately 4 hours for the ingested nutrients to spend in the small intestine. During this time, the small intestine uses enzymes to break down carbohydrates, proteins, and fats into their smaller subunits for absorption into the bloodstream.