Chap. 3

• What are the three processes that food goes under when eaten?

  digestion, absorption, elimination
• What is elimination?

  undigested portions of food and waste products removed from the body
• The GI tract


  a series of organs that work together to process food arranged in a long tube
• Mucosa

  innermost layer that surrounds the lumen
• Submucosa

  connective tissue and nerves
• Muscularis externa

  circular and longitudinal muscles that squeeze and propel food
• Serosa

  Outmost layer of the stomahhc
• Sphincters


  Muscles that control the passage of food material from organs
• Accessory organs of digestion

  salivary glands, liver, pancreas, gall bladder
• Mouth (enzymes)

  salivary amylase (carbs)

  lingual lipase (lipids)
• Stomach (enzymes)

  pepsin (proteins)

  gastric lipase (lipids)
• Pancreas (enzymes)

  Protease (proteins)

  pancreatic lipase (fat)

  pancreatic amylase (carbs)
• Small intestine (enzymes)


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• Gastrin

  secreted from the stomach, target organ is the stomach

  stimulates hcl and pepsinogen
• Secretin

  secreted by the small intestine, targets the pancreas

  stimulates the secretion of pancreatic bicarbonate
• Cholecystokinin

  secreted by the small intestine (dj), targets the pancreas and gall bladder

  stimulates the secretion of pancreatic digestion and gall bladder contraction
• What does the mouth digest?

  carbs and lipids
• What does the stomach digest?

  proteins and lipids
• What does the pancreas help digest?

  protein, lipids, carbs
• How does blood aid in the transport of nutrients?

  travels throughout the cardiovascular system
• How does the lymph help in the transport of nutreints?

  lacteals pick up most lipids and fat soluable vitamins
• How are carbs absorbed?

  active transport (glucose)

  facilitated diffusion (fructose)
• Where are carbs absorbed?

  capillaries then are sent to the liver through the hepatic portal vein
• Micelles

  transport lipid digestion products to the enterocyte for absorption into the lacteal
• Chylomicrons

  transported out of the enterocyte, through the lymphatic system, then are transferred through the blood stream into the thoracic duct
• Proteins

  enterocyte in the small intestine has different sites that specialize in the transport of AAs, di- + tri-peptides
• Where are proteins absorbed?

  into the capillaries then sent to the liver directly through the hepatic portal vein
• Peristalsis muscles

  moves the intestinal contents along
• Segmentation musles

  circular and longitudinal mucles contract to mix food and enhance contact area with digestive juices and enterocytes
• Chewing

  moistens the food and mechanically breaks it into smaller pieces
• Saliva

  contains digestive juice secreted by the salivary gland
• Enzymes

  chemicals that induce chemical changes in substrate to promote bodily processes
• Bolus


  mass of food chewed by the mouth
• Epiglottis

  covering the opening to the trachea during swallowing
• Esophagus

  propels food from the mouth to the stomach
• Peristalsis


  muscular contrations that move food through the GI tract
• Gastrin

  hormone secreted by the stomach lining. converts pepsinogen to pepsin
• Intrinsic factor

  proteins to absorb vitamin B12
• Pepsin

  digests protein
• HCL acid

  denatures proteins