Activity 1. The Food Journey
1. How the food changes consistency and form
The consistency and form of food changes, as physical and chemical digestion are facilitated by the digestive system. Starting from the mouth or oral cavity, food undergoes the process of ingestion, mastication and hydrolysis. Here, food is mechanically digested through chewing or mastication, which cuts the food into smaller pieces. At the same time, chemical digestion takes place, as saliva aids in the breakdown of food, and bolus, a semi-solid paste, forms for easier swallowing. Through deglutition, the bolus goes down into the pharynx, esophagus, and then stomach. In the stomach, the churning action, with the help of HCl, pepsin, and other gastric juices, turns the bolus into chyme, a more fluid-like substance. The chyme then moves down to the small intestine and large intestine, where the nutrients, water and electrolytes are absorbed, respectively. After then, it will become feces, which are temporarily stored in the rectum, and are excreted through the anus.
2. How the body was able to absorb the nutrients from the foods we eat.
In line with the process in the previous question, the food is converted into different consistencies and forms, which allow nutrients to be converted into a form that can be absorbed by the body. Herewith, the full absorption of nutrients mainly happens in the small intestines. As the longest part of the gastrointestinal tract, it is the site of nutrient absorption into the bloodstream. With the help of enzymes in the intestines, and from the pancreas and liver (bile), chyme is mixed with various digestive juices and enzymes for further chemical digestion and nutrient absorption. The finger-like villi in the small intestines absorb most of the nutrients and redirect them to enter the bloodstream.
References
Tortora, G. J., & Derrickson, B. H. (2020). Principles of Anatomy and Physiology (16th ed.). Wiley.