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DIGESTIVE STRUCTURES AND FUNCTIONS Structure Function(s) mouth receives food; site of chemical digestion of starch. tongue mixes food with saliva; moves food between teeth for chewing and to pharynx for swallowing; contains tastebuds. teeth mechanical digestion = breaks food into smaller pieces for easier swallowing and to increase surface area for enzymes. salivary glands produce saliva which lubricates food for easier swallowing and which contains salivary amylase to begin digestion of starch. pharynx passageway for both food (into esophagus) and air (into trachea). epiglottis covers trachea during swallowing to prevent entry of food. esophagus transports food bolus from pharynx to stomach by peristalsis cardiac sphincter closes during stomach churning to prevent chyme (containing HCL) from moving back into esophagus stomach mechanical digestion of food chyme; chemical digestion of proteins pyloric sphincter opens and closes to allow chyme to enter small intestine, from stomach, in small squirts duodenum receives bile from the liver, and enzymes and sodium bicarbonate from the pancreas gall bladder stores and concentrates bile small intestine site of digestion of all food substrates, and of absorption of all nutrient molecules. appendix thought to play a role in the immune response large intestine (colon) absorption of water and salts; E. coli bacteria within colon produce useful vitamins and amino acids which are absorbed through lining of colon rectum stores feces prior to defecation = release from body anus allows feces to exit the body or digestive tract.
