1. How does the food change in consistency and form?
Food is broken down into small molecules through the process of digestion. The GI tract and accessory digestive organs play roles in digestion. It starts off with the mouth where food is maneuvered by tongue, ground by the teeth, and mixed with saliva, thereby reducing it to an easily swallowed mass called bolus. The bolus then passes through the pharynx, into the esophagus, and into the stomach. In the stomach, through various movements, the gastric contents are mixed with gastric juice, becoming a soupy liquid, called chyme. Chyme is then squirted down into the small intestine, where digestion and absorption of nutrients occur. From the small intestine, chyme travels to the large intestine where it is prepared for elimination. In the large intestine, chyme becomes solid or semisolid due to water absorption and is now called feces, which is to be excreted.
2. How could the body absorb the nutrients from the foods we eat?
Absorption occurs via diffusion, facilitated diffusion, osmosis, and active transport. Around 90% of all absorption of nutrients takes place in the small intestine, while the other 10% occurs in the stomach and large intestine. In the small intestine, its lengthy structure provides a larger surface area for absorption, and this area is further enhanced by circular folds, villi, and microvilli.