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Review Sheet: The Digestive System 1. 2. Know the diagram of the digestive system. Explain the difference between mechanical and chemical digestion. Where in the digestive system does each occur? Mechanical digestion required muscular movement and chemical digestion requires enzyme. 3. What is homeostasis? The balance of the body’s internal environment; must be within narrow ranges 4. What is ingestion? The taking in of food Where does it occur? mouth 5. What are the 4 steps of digestion? Ingestion, mechanical & chemical digestion, absorption, elimination 6. Describe the process of swallowing. Include the words: teeth, salivary glands, tongue, bolus, pharynx, epiglottis and esophagus in your description. As you ingest food, your teeth mechanically break down the food in order to increase the surface area and the salivary glands release saliva which contains salivary amylase to chemically break down food. Your tongue assists with the movement of food and the formation of the bolus. As you swallow, your soft palate contracts to cover the nasopharynx region and the bolus moves through the pharynx. As the bolus passed by the flap of tissue called the epiglottis, it forces the epiglottis down to cover you trachea thereby allowing the bolus to enter the esophagus. 7. What are the functions of saliva? Antibacterial action, moisten food and mouth (including taste buds) and break down starch with the catalyst salivary amylase. 8. How many pairs of salivary glands are there? 3 9. Give the enzymatic reaction (substrate, enzyme and product) that result in the oral cavity. What is the optimum pH for this enzyme? starch amylase maltose at a pH of 7 10. What is the pharynx? The region between the mouth and the lower tubes. Name the two tubes that are located there. Trachea and esophagus 11. What is the epiglottis? The flap of tissue that covers the trachea when bolus passed it Name its function. Covers the trachea the prevent choking 12. What is peristalsis? Wave-like muscular contractions that will push the food through the digestive tract 13. What is a sphincter? A muscular valve that controls substances from entering or exiting Name the sphincter that prevents food from going back into the esophagus. Cardiac or esophageal sphincter Name the sphincter that prevents food from going back into the stomach from the small intestine. Pyloric sphincter 14. What is gastric juice? The juice secreted from the cells of the stomach Name the 3 substances that are secreted in the stomach. HCl, muscous, pepsinogen 15. What is the optimum pH of pepsin? 2 16. Why is pepsin secreted as pepsinogen from the stomach wall? Pepsinogen is the inactive form of pepsin. Pepsin digests protein and therefore would digest the protein in the cell membranes of the cells that are secreting it and therefore, the stomach cells secrete the inactive form so that only the proteins in the food are digested and not the cell membrances. 17. What is the function of the mucus layer that lines the stomach? Protects the stomach lining (the cells) from the acidity of the gastric juices 18. What is the name of the semi liquid mass in the stomach? chyme 19. a) What is the liver? An accessory organ that contributes to digestion b) Explain the functions of the liver. Produces bile, destroys old RBCs; breaks down hemoglobin; regulate blood glucose levels; produces urea; produces blood plasma proteins; produces and regulates cholesterol; stores iron ion and fat soluble vitamins; detoxifies blood c) Explain 2 disorders associated with the liver. Cirrhosis & jaundice d) What are gall stones? Crystallization of cholesterol in bile in which the crystals become too large and block the bile duct. 20. What is the function of the gall bladder? Stores excess bile 21. Name the 2 main functions of the pancreas. Produces pancreatic juices & secretes insulin & glucagon 22. Explain the function of insulin and glucagon. Insulin is secrete if blood glucose levels are too high and therefore, “encourage” liver cells to take up glucose. Glucagon is secrete if blood glucose levels are too low and therefore, communicates with liver to release glucose into blood (glycogen, a polymer, breaks down into glucose, the monomer) 23. What is the duodenum? The first portion of the small intestine. 24. What is bile? Substance secreted by liver, stored in gall bladder that acts in the small intestine to emulsify fat into fat droplets (smaller fats to increase surface area of fat) Why is it not considered to be an enzyme? Does not chemically break down fat, just physically whereas enzymes assist with chemical reactions. What is meant by emulsification? The breaking down of fat into fat droplets. 25. What is pancreatic juice? The mixture (juice) that is directly secreted from the cells of the pancreas. This juice is produces in the pancreas but acts in the small intestine 26. What is intestinal juice? The mixture (juice) that is directly secreted from the cells of the small intestine 27. Give the enzymatic reactions that occur in the small intestine. All those enzymes in the intestinal juice and the pancreatic juice. See you notes What is the optimum pH for these enzymes? Slightly basic (about 8 to 9) 28. How is stomach acid buffered in the small intestine? By sodium bicarbonate that is released as from the pancreas and travels via the pancreatic duct 29. What is absorption? The ability of the small intestine to move the nutrients from the digestive system into the blood and lymph system (lacteal) How is the small intestine specialized for absorption? By significantly increasing the surface area (the villi and microvilli) What is absorbed here? Monosaccharides (glucose) and aa into the blood capillaries and glycerol and fatty acids into the lacteal. 30. Explain how surface area is increased in the digestive system. Convoluted lining of the system (ie fold in stomach and villi/microvilli in the intestinal walls) 31. Draw a villus and explain the function of its parts. 32. Describe the role of E. coli in the colon. Further breaks down material that has not been digested thus far 33. Contrast endocrine and exocrine glands. Endocrine secretes hormones into the blood stream and exocrine secrete products into ducts for transport Give an example from the digestive system. Pancreas does both via the pancreatic duct and directly secretes insulin and glucagon into the blood stream 34. What is absorbed in the colon? Water and salts 35. Explain two problems that can be associated with elimination. Diarrhea (failure to absorb water) and constipation (too much water is absorbed) 36. Explain the complete digestion of carbohydrates, proteins, nucleic acids and fats as they pass through the digestive system. Don’t need to know the names of these, just consider it trypsin 37. Which of the following is considered an accessory organ in the digestive system? a) pharynx b) esophagus c) stomach d) pancreas 38. In the body, glucose is stored in the liver as a) starch b) protein c) glycogen d) glucagons e) amino acids 39. Liver does NOT function in the production of a) bile b) digestive enzymes c) blood proteins d) glycogen 40. The hepatic portal vein is located between a) the hepatic vein and the vena cava b) the mouth and the stomach c) the pancreas and the small intestine d) the small intestine and the liver 41. What is the role of HCl in the stomach? a) symptom of a digestive disorder b) only to cause stomach ulcers c) digestive enzymes to hydrolyze fats d)aids in the digestion of starch e)activates a digestive enzyme, pepsin 42. Name the structure and organ that has microvilli, maltase, and absorbs nutrients. a) villus, large intestine b) villus, small intestine c) villus, stomach d) folds, stomach e) pyloric sphincter, appendix 43. In mammals, fats are absorbed a) in the large intestine b) in the stomach c) into the blood capillaries d) into the lacteal e) none of the above are correct 44. At body temperature, which of these combinations is most likely to result in digestion? a) protein, water, pepsin b) protein, HCl, pepsin c) protein, bile, pepsin d) protein, sodium bicarbonate, pepsin 45. At body temperature, which of these combinations is most likely to result in digestion? a) fat, bile, sodium bicarbonate, lipase b) fat, bile, sodium bicarbonate, pepsin c) fat, HCl, maltase d)fat, bile, HCl, sodium bicarbonate, trypsin 46. Which of the following human digestive enzymes is incorrectly matched to its substrate? a) pepsin – protein b) trypsin- nucleic acid c) salivary amylase – starch d) lipase – fat e)maltase-maltose 47. Which organ in the human body produces maltase and peptidases? a) mouth b) esophagus c) stomach d) small intestine e) large intestine Use the following information to answer the next 4 questions a) protein pepsin peptides b) starch amylase maltose c) maltose maltase glucose d) fat lipase fatty acids + glycerol 48. Which reaction above is aided by a pH of about 2- 3? a) a b) b c) c d) d e) none 49. Which reaction above occurs in both the mouth and duodenum a) a and c b) a c) d d) c and d e) b 50. In the reactions above, in order for reaction “d” to proceed efficiently a) the pH must be at least 2 b) pancreatic juice must be secreted c) bile must be present d) HCl must be present e) pancreatic juice must be secreted and bile must be present 51. In the reactions above, reaction “a” occurs in the a) stomach b) oral cavity c) large intestine d) small intestine e) esophagus 52. Protein digestion is confined to the a) mouth, stomach, small intestine b) stomach, small intestine c) stomach, esophagus, small intestine d)mouth, large intestine e) small intestine, large intestine, mouth 53. The fingerlike projections along the surface on the small intestine are called a) mucosa b) lacteals c) capillaries d) villi e) appendix 54. Microvilli form a brush border on the cells of the a) esophagus b) stomach c) duodenum d) tongue e) pharynx 55. Which of these organs has food for the least time and participates least in digestion? a) mouth b) esophagus c) stomach d) small intestine e) large intestine 56. The main function of the esophagus is to a) digest proteins b) digest carbohydrates c) transport food from the small intestine to the large intestine d)transport food from the mouth to the stomach e) transport food from the stomach to the large intestine 57. A correct function of the human stomach is a) to produce highly basic fluids to kill most bacteria b) to begin the absorption of most small food molecules, especially sugars and alcohol c) storage of food and mixing with digestive fluids to begin chemical digestion d) promotion of bacterial fermentation e) absorption of iron to build hemoglobin for red blood cells 58. The ___ functions to store food, kill bacteria, and partially digest protein a) mouth b) esophagus c) stomach d) small intestine e) large intestine 59. Food and liquid is prevented from entering the trachea by the a) pharynx b) larynx c) epiglottis d) glottis e) sphincter muscle Use the following diagram to answer the next 6 questions. 60. Which structure above stores food, has limited digestion, and secretes HCl? x 61. In the diagram, which structure is the primary site for digestion and absorption of food? v 62. In the diagram, the esophagus is designated by the number t 63. Into which structure does food pass but no digestion takes place? t+z 64. In the diagram, the food material that is absorbed will first enter which organ? u 65. In the diagram which structure is the liver? u 66. The digestive system functions in the a) chemical breakdown of food b) mechanical breakdown of food c) elimination of waste products d) absorption of food molecules e) all of the above 67. Which of the following is NOT a function of the digestive system? a) ingestion of food b) digestion of food c) absorption of food d) elimination of digestible wastes e)elimination of non digestible wastes 68. Muscles that encircle tubes and act a valves are called a) constrictors b) dilators c) sphincters d) lacteals e) mucosa 69. The duodenum is the site for a) a duct from the liver that introduces bile b) a pancreatic duct that introduces basic fluids to neutralize the stomach acid c) highly acidic stomach contents d) all of the above 70. Water is absorbed primarily by the a) colon b) duodenum c) anal canal d) esophagus 71. Fat absorption differs from other foods because its breakdown products are a) formed in the large intestine b) absorbed directly into the blood c) absorbed into the lacteal d)absorbed only when glucose is not present 72. Villi serve to a) absorb nutrients b) secrete bile c) produce antibodies d) synthesize vitamins Match the words/description on the right with the terms on the left. There may be several answers for each term. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82. 83. 84. 85. Bolus _______N, O, P___________ Epiglottis_________Q______________ Esophagus ______A, N_____________ Sphincter relaxed _____M___________ Sphincter contracted ____L_________ Stomach __C, D, E, F, I, J, K__ Mechanical digestion ______G, I _____ Peristalsis______N______ Gastric glands ___C, D, E, F___ Duodenum ______B________ Small Intestine_____B, H ________ Villi _________B__________ Intestinal villi cells __________B_______ A. extends from pharynx to the stomach B. increased surface area C. gastric pits D. chyme E. pepsin, HCl, and mucus F gastric juice G. chewing H ~ 3 m long I churning J stores food K continuous with esophagus and duodenum L closed M open N swallowing O mixed with saliva P tongue Q flap of tissue to cover trachea