- How does the food change in consistency and form?
Food changes in consistency and form through the following processes:
- Mouth (Mechanical and Chemical Digestion): The food is manipulated by the tongue, ground by the teeth, and mixed with saliva. As a result, the food is turned into a soft, flexible, easily swallowed mass called bolus. Moreover, the salivary glands present in the mouth secrete salivary amylase and lingual lipase to break down large starch macromolecules into simple sugar molecules.
- Stomach: Food undergoes churning and hydrolysis with the presence of digestive enzymes. These processes turn the bolus into a fluid substance called chyme.
- Small Intestines: The enzymes present in the small intestine act upon the chyme. Furthermore, a process called segmentation further breaks up the food in order for absorption to take place.
- Defecation: Once all the needed components are absorbed by the body, the waste products are eliminated in the form of feces.
- How could the body absorb the nutrients from the foods we eat?
As the food goes down the gastrointestinal tract, it is continuously being broken down into smaller pieces that could easily be absorbed by the body. However, the absorption of nutrients mainly happens in the small intestines. In the duodenum, the chyme mixes with digestive enzymes from the pancreas and bile from the liver. As the broken down food goes through the jejunum and ileum, the villi helps in the absorption of nutrients through osmosis, diffusion, facilitated diffusion, and active transport. The food that won’t be digested then proceeds to the large intestine where some nutrients can still be absorbed before the waste products are eliminated.