10.2 The Digestive System

Notes

The digestive system breaks food into small molecules the body can absorb.

• Mechanical digestion physically breaks food into smaller pieces (chewing, stomach churning).
• Chemical digestion uses enzymes to break molecules apart. Saliva's amylase starts digesting starch in the mouth.
• Path of food: mouth → esophagus → stomach → small intestine → large intestine.
• The stomach uses acid and the enzyme pepsin to start protein digestion.
• The small intestine finishes digestion and absorbs nutrients through finger-like villi that increase surface area.
• The liver makes bile (breaks fat into small droplets); the pancreas makes digestive enzymes.
• The large intestine absorbs water.