GI Summary Table

• motility: mastication and deglutition


  mouth and pharynx
• motility: peristalsis


  esophagus
• motility: receptive relaxation, peristalsis, retropulsion, and gastric emptying


  stomach
• motility: segmentation and MMC


  small intestine
• motility: haustrations, mass movement, and defecation


  large intestine
• chewing begins; initiation of swallowing reflex

  mouth and pharynx
• • moisten and dissolve food; help neutralize ingested acid
  • lubrication
  • polysaccharide-digesting enzyme (relatively minor function)
  • help prevent tooth and gum decay

  salivary glands
• • move food to the stomach by peristaltic waves
  • lubrication 


  esophagus
• • store, mix, dissolve, and continue the digestion of food; regulate emptying of dissolved food into the small intestine
  • solubilization of some food particles; kill microbes; activation of pepsinogen to pepsin
  • begin the process of protein digestion in the stomach
  • lubricate and protect epithelial surface

  stomach
• • secretes of enzymes and bicarbonate; also has nondigestive endocrine functions
  • digest carbohydrates, fats, proteins, and nucleic acids
  • neutralize HCl entering the small intestine from the stomach

  pancreas
• • secretion of bile
  • solubilize water-insoluble fats
  • neutralize HCl entering the small intestine from the stomach
  • elimination in feces

  liver
• store and concentrate bile between meals

  gallbladder
• • digestion and absorption of more substances; mixing and propulsion of contents
  • digestion of macromolecules
  • maintain fluidity of luminal contents
  • lubrication and protection

  small intestine
• • storage and concentration of undigested matter; absorption of ions and water; mixing and propulsion of contents; defecation
  • lubrication


  large intestine
• endocrine hormones: gastrin and SST


  stomach
• endocrine hormones: CCK, secretin, GIP


  small intestine
• exocrine secretions:

  • ions and water
  • mucus
  • amylase, lipase
  • antibodies and other immune factors

  salivary glands
• exocrine secretions:

  • mucus


  esophagus
• exocrine secretions:

  • histamine
  • HCl, intrinsic factor
  • pepsin
  • mucus, bicarbonate

  stomach
• exocrine secretions:

  • enzymes (know names, substrates, products)
  • bicarbonate


  pancreas
• exocrine secretions:

  • bile salts
  • bicarbonate
  • organic waste products and trace metals

  liver
• exocrine secretions:

  • enzymes
  • ions and water
  • mucus


  small intestine
• exocrine secretions:

  • mucus
  • bicarbonate
  • K+


  large intestine