Your Digestive System and How It Works
Digestion starts when you smell food, triggering your salivary glands to release the first set digestive enzymes that help break down food. Macronutrients (carbs, fat, protein and fiber) are digested at different stages, with help from the stomach, small intestine, liver and pancreas.
Chewing is part of digestion, so healthy digestion starts by slowly and thoroughly chewing each bite. Your digestive system includes your mouth, esophagus, stomach, small intestine, large intestine, anus, pancreas, gallbladder and liver. Digestion takes 10 to 73 hours on average. That’s divided into:
- Gastric (stomach) emptying: 2-5 hours
- Small intestine transit: 2-6 hours
- Large intestine transit: 10-59 hours
Why the variance? It depends on what you eat — digesting processed food is faster but provides fewer nutrients. A big raw salad or a meal high in fats and protein will be harder to break down and take longer. Your body uses a combination of movements (chewing, squeezing and mixing) and digestive juices (digestive enzymes, bile and stomach acids) to break down food and move it through your body.
Here’s what happens during digestion:
- Mouth: As you chew, your salivary glands release saliva and enzymes. The softened, fully chewed food is called bolus.
- Esophagus: That bolus is swallowed and heads to the esophagus, the tube that connects to your stomach. A set of contracting sphincter muscles opens to let the bolus pass into the stomach.
- Stomach: The stomach (gastric) acids further break down food. The gastric acids and enzymes mix to form “chyme.”
- Small intestine: The chyme heads to the small intestine. More enzymes are released to keep digestion going. At this stage, the nutrients from the foods you eat are absorbed into the bloodstream.
- Large intestine: What’s left is waste, so your body gets ready for excretion (pooping).
Liver, gallbladder and pancreas: These organs help along the way by releasing enzymes and getting rid of certain nutrients and waste.