Food is first chewed in the mouth and is mixed with saliva which breaks down starch into maltose. These processes result in forming a mass called bolus which is then propelled by the esophagus into the stomach. The stomach then mixes the bolus with gastric juices which contain hydrochloric acid which denatures proteins and pepsin to form chyme and further churns the food with stomach muscle contractions.
The chyme is then sent to the small intestine where enzymes from accessory structures such as the pancreas and liver such as bile act on the chyme. This results with carbohydrates being broken down into monosaccharides, lipids being emulsified, and finally proteins being broken down into amino acids.
The nutrients are then absorbed by the small intestine using structures such as villi and microvilli which increase the surface area used for absorption of nutrients. The monosaccharides are absorbed by either active transport or facilitated diffusion, similarly the amino acids are absorbed through active transport. Lipids emulsified by bile and fat-soluble vitamins such as vitamins A, D, E and K are absorbed into intestinal cells through diffusion, with water-soluble vitamins such as vitamin B and C are absorbed directly into the blood. Finally in the large intestine, the remaining water from the digested materials is absorbed, forming solid feces from the food consumed.