ACE Personal Trainer Practice Exam

During which process is food absorbed into the circulatory system?

1. Mechanical digestion

2. Chemical digestion

3. Metabolism

4. Elimination

The correct answer is: Chemical digestion

The absorption of food into the circulatory system occurs primarily during chemical digestion. This process breaks down the food into smaller molecules that can be absorbed by the intestines. During chemical digestion, enzymes and acids work to further degrade food components, such as carbohydrates, proteins, and fats, into their respective building blocks—simple sugars, amino acids, and fatty acids. Once these nutrients are broken down sufficiently, they are absorbed through the intestinal walls and then enter the bloodstream. This allows the body to transport these essential nutrients to various cells and tissues where they are needed for energy, growth, and repair. Mechanical digestion, in contrast, involves the physical breakdown of food into smaller pieces but does not contribute to the chemical transformation required for nutrient absorption. Metabolism refers to the biochemical processes that occur after absorption, where the absorbed nutrients are utilized by the body for energy and growth. Elimination is the final stage of the digestive process, where indigestible substances are excreted from the body, and does not involve absorption. Hence, the focus on how food is absorbed highlights the significance of chemical digestion in this critical aspect of nutrition.