- How does the food change in consistency and form?
Food must be broken down in order for proper absorption of nutrients to occur. Once the food enters the mouth, both mechanical and chemical digestions take place. Mechanical digestion breaks the pieces of food into smaller portions for easier swallowing and digestion through the mastication accomplished by the grounding of teeth. Chemical digestion in the mouth is carried out by the chemicals present in saliva, particularly amylase, which breaks down carbohydrates, and lipase, which breaks down fats. These digestive processes transform food into what is now identified as bolus.
Food then travels down to the pharynx, which propels bolus into the stomach. In the stomach, mechanical digestion continues to occur through propulsion, which is the peristaltic wave movements from the fundus to the pylorus. It is then followed by retropulsion, which then produces movements that squeeze particles back into the body of the stomach. Both of these gastric movements allow for the bolus to be properly mixed with gastric juices and further break the food into smaller portions. Once mixed with gastric juices, bolus is transformed into chyme.
Chyme will be able to pass through the pyloric sphincter once its food particles are small enough. Chyme will then make its way to the intestines, where vitamins, electrolytes, water, and other chemicals are absorbed. Chemical digestion is also completed in the small intestine where pancreatic juice, bile, and intestinal juice further digest carbohydrates, proteins, and lipids. As chyme makes its way down the small intestine, it solidifies, transforming it into feces, which shall be eliminated through the anus.
- How could the body absorb the nutrients from the foods we eat?
Absorption of nutrients occur mainly in the small intestines as it breaks down food into simpler forms like carbohydrates, fatty acids, amino acids, and so on. The of presence absorptive cells, villi, and microvilli allows for these simpler forms to be absorbed and to enter into the blood circulation.