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How does the food change in consistency and form?
The food that goes down in the body is changed in form and consistency as it passes through the digestive system. At first, the food is ingested through the mouth and is dissolved by chewing and is assisted by the salivary glands through the secretion of saliva. After, a bolus is formed which is the rounded mass of chewed substance. This bolus proceeds to the gastrointestinal tract which secrete amounts of different substances that help in breaking down the food. The nutrients from the food is also absorbed by the GI tract, which then converts the food into substances that can be useful to the body. When the food reaches the stomach, the food turns into a liquid mixture called chyme. By the time the processed food enters the small intestine, water is reabsorbed making the chyme solid or semisolid and forming the feces.
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How could the body absorb the nutrients from the foods we eat?
The food we eat is first broken down into smaller pieces before being absorbed into the body. Nutrient absorption usually occurs in the small intestine, but small amounts of water, ions, short-chain fatty acids, and some drugs are already absorbed before entering the small intestine. The broken down food passes the absorptive epithelial cells lining the mucosa and is distributed throughout the body. This process is usually done through diffusion, facilitated diffusion, osmosis, and active transport. Last absorption occurs in the large intestine where some water, ions, and vitamins that were not able to be absorbed in the stomach and small intestine are reabsorbed.