Digestive System

• Mechanical digestion


  Chewing up food (mastication)
• Chemical digestion


  Enzymes breaking down molecules
• Saliva


  Contains the enzyme salivary amylase that breaks down starches into sugars
• Pharynx


  Throat
• Epiglottis


  Flap that covers the opening to the trachea to prevent food from entering the lungs
• Peristalsis


  Wave-like contractions that push food down the esophagus
• Heartburn


  Painful burning in the esophagus caused by stomach acid backing up
• Stomach

  Mechanical and chemical digestion occurs here, contains hydrochloric acid and the enzyme pepsin
• Peptic ulcer


  Open sore in the lining of the stomach, small intestine or esophagus caused by stomach acid
• Small intestine


  Where most digestion and absorption of nutrients occurs, lined with villi and microvilli to increase surface area
• Pancreas


  Produces pancreatic juice with enzymes and sodium bicarbonate to neutralize stomach acid, also produces insulin and glucagon
• Liver


  Produces bile to help digest fats
• Gallbladder


  Stores and releases excess bile
• Cecum and appendix


  Cecum contains bacteria that digest cellulose in herbivores, appendix is an immune organ in humans
• Large intestine


  Absorbs majority of water from waste, contains bacteria that produce vitamins
• Diarrhea is when the colon does not remove enough water, often due to infection
• Constipation is when waste moves too slowly through the intestine, causing dry, hard feces
• Feces contains cells shed from the GI tract, bacteria, and indigestible material like cellulose