Your digestive system turns food into small substances your body can use for energy, growth, and repair. It works through a series of organs, with help from muscles, nerves, and digestive juices.
Step by step: the journey of food
- Mouth: Your teeth chew food into smaller pieces. Saliva moistens it and contains an enzyme that begins breaking down starch, a type of carbohydrate. Your tongue helps form the food into a soft ball so you can swallow.
- Esophagus: After you swallow, food travels down this muscular tube. Wave-like squeezes, called peristalsis, push it toward your stomach.
- Stomach: The stomach churns food and mixes it with acid and enzymes. These juices help break down food, especially proteins, and kill many germs. The food becomes a thick liquid.
- Small intestine: Most digestion and nutrient absorption happen here. The liver makes bile, which helps break up fats, and the gallbladder stores and releases bile. The pancreas sends enzymes that help digest carbohydrates, proteins, and fats. Tiny finger-like structures called villi absorb nutrients through the intestine wall into the blood. The blood carries them around your body.
- Large intestine: What remains moves here. The large intestine absorbs much of the remaining water and salts. Helpful bacteria also live there and break down some leftover material.
- Rectum and anus: The leftover solid waste, called stool, is stored in the rectum and leaves the body through the anus during a bowel movement.
Two kinds of digestion
- Mechanical digestion physically breaks food into smaller pieces, such as chewing and stomach churning.
- Chemical digestion uses acids and enzymes to split food molecules into smaller nutrients your body can absorb.
In short: food is broken down, useful nutrients and water are absorbed, and the remaining waste is removed. Eating a variety of foods, drinking water, and getting fiber from foods such as fruits, vegetables, beans, and whole grains can help your digestive system work well.