- How the food changes consistency and form
In our mouth, food is mechanically and chemically broken down by our teeth and saliva, resulting in a semi-solid paste called a bolus. Movements of the smooth muscles, known as peristalsis, help move that bolus down your esophagus. After this, a sphincter opens and dumps the food when it reaches your stomach. The bolus is further broken into an acidic "soup" called chyme. Chyme then passes through the pyloric sphincter and enters the small intestine, which absorbs most nutrients. Next, undigested materials (and some water) travel to the large intestine, changing its form from a liquid into stool removed from the body as feces.
2. How the body was able to absorb the nutrients from the foods we eat.
For the nutrients to be transported and used by our bodies, the food we eat must be broken down by our digestive system into smaller parts by using either motion (e.g., chewing) or digestive juices (e.g., enzymes). For example, carbohydrates must be broken down into glucose, protein into amino acids, and lipids or fats into fatty acids. The small intestines make digestive juice, which mixes with bile and pancreatic juice to complete the breakdown of proteins, carbohydrates, and fats. In addition, bacteria in your small intestine make some of the enzymes you need to digest carbohydrates.