1. How the food changes consistency and form
Once the food enters the mouth, it undergoes mechanical and enzyme-assisted breakdown namely, chewing and hydrolysis respectively. These two processes make a sphere of digested food called bolus. It enters the esophagus and through peristalsis, it propels the bolus downward along the gastrointestinal tract. In the stomach, waves of peristalsis occur, mixing the gastric juice with the bolus. As a result, it is broken down to a soapy fluid called chyme. Its consistency and form make it easier for the small intestine to absorb the chyme’s nutrients. Any undigested or unabsorbed material left in the small intestine passes on to the large intestine where absorption of water occurs. Water absorption in the large intestine makes the chyme turn into solid or semisolid in form called feces. Finally, it is held there until it passes through the anus for expulsion.
2. How the body was able to absorb the nutrients from the foods we eat.
The absorption of nutrients mainly occurs in the small intestine while a miniscule amount of nutrients is also absorbed in the large intestine. The chyme that is made in the stomach together with the chemical and mechanical phases of digestion in the small intestine enables the digestive nutrients to pass through the absorptive epithelial cells lining the mucosa to the blood or lymph. Absorption of materials occurs via diffusion, facilitated diffusion, osmosis, and active transport.