Activity 1. The Food Journey
How does the food change in consistency and form?
The food we consume primarily comprises molecules that are too large for direct use by our body cells. Hence, these foods need to undergo a process of breakdown into smaller molecules that can be readily absorbed by body cells. Within the digestive system, the movement of food from the mouth to the stomach is facilitated by swallowing, and mechanical digestion takes place. Mechanical digestion in the mouth is a result of mastication or chewing. During this process, the tongue manipulates the food, the teeth grind it, and saliva mixes in. Consequently, the food transforms into a soft, flexible, and easily swallowable mass known as a bolus or lump. In this phase, food molecules begin to dissolve in the water present in saliva. Once the essential nutrients have been absorbed and the liquid residue of leftover food has traversed the small intestine, it proceeds to the large intestine.
How could the body absorb the nutrients from the foods we eat?
About 90% of nutrient absorption occurs in the small intestine, while the remaining 10% takes place in the large intestine. The small intestine plays a pivotal role in extracting glucose, amino acids, fatty acids, vitamins, and minerals from food for cellular use. This process is facilitated by villi, microscopic brush-like linings in the small intestine that act like combs, extracting vital nutrients from the digested food exiting the stomach. The efficiency of nutrient absorption is heightened by the villi's ability to expand the surface area inside the small intestine. With hundreds of thousands of villi lining the gut, there is a substantial surface area available for optimal nutrient absorption. Once nutrients diffuse into the villi, they directly enter the bloodstream, where they can contribute to cellular functions, including protein synthesis and energy generation.
Reference
Tortora, G., & Derrickson B. (2017). Principles of Anatomy and Physiology (15th ed.). Wiley.