Human Physiology 18

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NursyDaisy
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100836
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Human Physiology 18
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2011-10-11 18:46:46
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Human Physiology
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The Digestive System
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  1. What process adds water to large molecules in the GI tract in order to break them down into monomers?
    hydrolysis
  2. Within what organ does absorption of the products of digestion take place?
    the small intestine
  3. What process involves taking food into the mouth?
    ingestion
  4. What is the physiological term for the chewing of food and mixing it with saliva?
    mastication
  5. What is the physiological term for swallowing?
    deglutition
  6. What are rhythmic wave-like contractions that move food through the GI tract?
    peristalsis
  7. What is the passage of digested end products into the blood or lymph?
    absorption
  8. What is the complete term for GI tract?
    gastrointestinal tract
  9. What are the two general categories of structures that form the digestive system?
    the gastrointestinal tract and the accessory digestive organs
  10. List the organs of the gastrointestinal tract.
    • oral cavity
    • pharynx
    • esophagus
    • stomach
    • small intestine
    • large intestine
  11. List the accessory organs of the digestive system.
    • teeth
    • tongue
    • salivary glands
    • liver
    • gallbladder
    • pancreas
  12. What is the general term for the layers of the digestive system?
    tunics
  13. List the four layers of the digestive system from the lumen outwards.
    • mucosa
    • submucosa
    • muscularis
    • serosa
  14. What is the absorptive layer of the GI tract?
    the mucosa
  15. What increases the surface area of the absorptive surface of the GI tract?
    • the long length of the GI tract
    • folds
    • villi
    • microvilli
  16. What are the mucus-secreting cells of the GI tract?
    goblet cells
  17. What is the thick, highly vascular layer of connective tissue where absorbed molecules enter blood and lymphatic vessels?
    submucosa
  18. What layer of the GI tract is responsible for segmental contractions and peristalic movements?
    muscularis
  19. What are the two layers of the muscularis of the GI tract?
    the inner circular layer and the outer longitudinal layer
  20. What is the outer most layer of the GI tract?
    the serosa
  21. What cranial nerve carries impulses to and from the digestive system?
    the vagus nerve
  22. What regions of the spinal cord carry impulses to and from the GI tract?
    S2-S4
  23. What is the effect of the parasympathetic division of the ANS on the digestive system?
    It stimulates motility and secretions
  24. What is the effect of the sympathetic activity on the digestive system?
    It reduces peristalsis and secretory activity
  25. What intrinsic system of the GI tract controls its movements?
    the enteric nervous system
  26. What two general categories of signals influences the motiliy of the GI tract?
    paracrine and endocrea
  27. What enzyme is contained in saliva?
    salivary amylase
  28. What substance is chemically digested by the enzyme in saliva?
    starch
  29. During swallowing, what structure covers the glottis and prevents food from entering the larynx?
    the epiglottis
  30. What structure connects the oral and nasal cavities to the larynx and esophagus?
    the pharynx
  31. What structure connects the pharynx to the stomach?
    the esophagus
  32. What type of muscle occurs in the esophagus?
    • the upper third contains skeletal muscle
    • the middle third contains a mixture of skeletal and
    • smooth muscle
    • the terminal portion contains only smooth muscle
  33. Through what opening in the diaphragm does the esophagus pass?
    the esophageal hiatus
  34. What action propels food through the GI tract?
    peristalsis
  35. What circular muscle prevents reflux from the stomach into the esophagus?
    the gastroesophageal sphincter
  36. What is the most distensible part of the GI tract?
    the stomach
  37. What are the functions of the stomach?
    • storage of food
    • initial digestion of proteins
    • killing bacteria with high acidity
    • moving chyme into the intestine
  38. What circular muscle prevents chyme from leaving the stomach and entering the small intestine?
    the pyloric sphincter
  39. What is the region of the stomach where the esophagus enters it?
    the cardia
  40. What is the dom-]shaped region of the stomach?
    the fundus
  41. What is the main portion of the stomach?
    the body
  42. What is the terminal, funnel-shaped region of the stomach?
    the pylorus
  43. What are the folds within the stomach?
    gastric rugae
  44. What are the cells that line the gastric pits within the folds of the gastric mucosa?
    gastric glands
  45. What cells of the gastric glands secrete HCl?
    parietal cells
  46. What cells of the gastric glands secrete pepsinogen?
    chief cells
  47. What process moves H+ into the lumen of the stomach?
    active transport via an H+/K+ pump
  48. What nerve stimulates the secretion of HCl into the stomach?
    the vagus
  49. What hormone stimulates the secretion of HCl into the stomach?
    gastrin
  50. What are the functions of HCl in the stomach?
    It denatures proteins to make them more digestible, converts pepsinogen into pepsin, and kills bacteria
  51. Both HCl and pepsin can damage the gastric lining and produce a peptic ulcer. What normally prevents this?
    There is an adherent, stable layer of mucus on the lining. This mucus contains bicarbonate for neutralizing HCl and is a barrier to the actions of pepsin. The gastric epithelial cells contain tight junctions to prevent HCl and pepsin from penetrating the surface
  52. How often are gastric epithelial cells replaced?
    every three days
  53. What does pepsin digest?
    proteins
  54. What happens to salivary amylase in the stomach?
    It is inactivated by the acidity
  55. What commonly ingested substances are absorbed in the stomach?
    alcohol and aspirin
  56. What is the erosion of the mucous membrane of the stomach or duodenum caused by the action of HCl?
    peptic ulcer
  57. What bacterium is associated with most gastric ulcers?
    Helicobacter pylori
  58. What is the first segment of the small intestine?
    the duodenum
  59. What is the middle segment of the small intestine?
    the jejunum
  60. What is the terminal segment of the small intestine?
    the ileum
  61. What lie within each villus of the small intestine?
    • lymphocytes
    • capillaries
    • a central lacteal
  62. The microvilli of the small intestine create what?
    a brush border
  63. What are attached to the microvilli of the small intestine to aid in chemical digestion?
    brush border enzymes
  64. List the functions of the large intestine.
    • absorption of H2O
    • electrolytes
    • B & K vitamins
    • folic acid
  65. What term refers to the community of organisms living in the large intestine?
    microflora
  66. About how many species of bacteria live in the large intestine?
    400
  67. What do the bacteria of the large intestine produce?
    • folic acid
    • vitamin K
    • fatty acids
  68. How do the bacteria of the large intestine protect their host?
    They reduce the ability of pathogenic bacteria to infect the large intestine
  69. List the regions of the large intestine.
    • cecum
    • ascending colon
    • transverse colon
    • descending colon
    • sigmoid colon
    • rectum
    • anal canal
  70. What circular muscle lies between the small intestine and the large intestine?
    the ileocecal valve
  71. The small intestine absorbs most of the water ingested. Of the water entering the large intestine, what percentage is absorbed?
    90%
  72. How does the large intestine absorb water?
    By setting up an osmotic gradient established by Na+/K+ pumps
  73. What can the large intestine secrete?
    Na+
  74. What is the medical term for the waste products eliminated after digestion?
    feces
  75. What is the medical term for the elimination of feces?
    defecation
  76. What is the largest internal organ?
    the liver
  77. What is the histological term for cells that carry out the functions of the liver?
    heypatocytes
  78. What structures do hepatocytes form in the liver?
    hepatic plates
  79. How many cells thick are hepatic plates?
    1 or 2 cells
  80. What separates hepatic plates?
    fenestrated sinusoids
  81. What is the only organ capable of regenerating itself?
    the liver
  82. In some cases, such as alcohol abuse or viral hepatitis, regeneration of the liver does not occur. In such cases alcohol abuse or hepatitis can lead to what conditions?
    liver fibrosis and, ultimately, cirrhosis
  83. What vascular network carries the products of digestion from the GI tract to the liver?
    the hepatic portal system
  84. The liver receives blood from what two vessels?
    the hepatic portal system and the hepatic artery
  85. What are the functional units of the liver?
    liver lobules
  86. What product of the liver is secreted into the duodenum and takes part in the digestive process?
    bile
  87. What is the recirculation of compounds between the liver and intestine?
    enterohepatic circulation
  88. What are the five major categories of liver function?
    • detoxification
    • carbohydrate metabolism
    • lipid metabolism
    • protein synthesis
    • secretion of bile
  89. How much bile is produced every day?
    250-1500 ml
  90. Where is bile pigment (bilirubin) produced?
    • spleen
    • bone marrow
    • liver
  91. From what is bilirubin produced?
    heme groups (minus iron) from hemoglobin
  92. Free bilirubin is carried in the blood on what molecule?
    albumin
  93. Free bilirubin combines with glucuronic acid to form what substance?
    conjugated bilirubin
  94. What form of bilirubin is secreted in bile?
    conjugated bilirubin
  95. Conjugated bilirubin is converted by intestinal bacteria into what substance?
    urobilinogen
  96. What form of is absorbed by the intestine and is filtered out of the blood by the kidneys?
    urobilinogen
  97. What makes urine yellow and feces brown?
    urobilinogen
  98. Where is bile made?
    in the liver
  99. What structure functions to store bile?
    the gallbladder
  100. What is the digestive function of bile?
    to emulsify fats
  101. The liver removes hormones, drugs, and other biologically active molecules from the blood by what three processes?
    • excretion into bile
    • phagocytosis by Kupffer cells
    • chemical alteration of molecules
  102. What organ forms urea?
    the liver
  103. Through what two processes does the liver remove glucose from the blood?
    glycogenesis and lipogenesis
  104. Through what two processes does the liver release glucose into the blood?
    glycogenolysis and gluconeogenesis
  105. Through what process does the liver convert free fatty acids into ketone bodies?
    ketogenesis
  106. What substances are formed by the liver during fasting to provide an energy source for the body?
    ketone bodies
  107. What substance formed by the liver contributes the most to the colloid osmotic pressure of the blood?
    albumin
  108. What organ makes albumin in order to maintain the osmotic pressure of blood?
    the liver
  109. What organ produces clotting factors?
    the liver
  110. What accessory digestive organ lies deep to the stomach?
    the pancreas
  111. What clusters of cells within the pancreas carry out that organís endocrine function?
    the islet cells
  112. What two hormones are produced by the pancreas?
    glucagon and insulin
  113. What three digestive enzymes are made in the pancreas?
    • trypsin
    • lipase
    • pancreatic amylase
  114. What substance formed by the pancreas rises the pH of chyme?
    bicarbonate
  115. What enzyme digest proteins within the lumen of the small intestine?
    trypsin
  116. What enzyme digest carbohydrates within the lumen of the small intestine?
    pancreatic amylase
  117. What enzyme digest fats within the lumen of the small intestine?
    lipase
  118. What substances complete digestion on the epithelium of the small intestine?
    brush border enzymes
  119. What are the three phases of extrinsic gastric control?
    • cephalic
    • gastric
    • intestinal
  120. What phase of extrinsic gastric control is carried out by the brain via the vagus nerve?
    cephalic
  121. What phase of gastric control involves the arrival of food in the stomach?
    gastric phase
  122. What hormone produced by the stomach brings about the secretion of HCl and pepsinogen?
    gastrin
  123. What stimulates the release of gastrin?
    short polypeptides and amino acids
  124. What happens in the gastric phase of digestion if the pH in the stomach drops to less than 2.5?
    HCl production decreases and will stop at a pH of 1
  125. What phase of gastric control begins as chyme enters the small intestine?
    the intestinal phase
  126. What are the neural and hormonal actions of the small intestine on the stomach as chyme enters the small intestine?
    A neural reflex inhibits gastric motility and secretion. Fat stimulates the small intestine to secrete enterogasterones (hormones) which also inhibit gastric motility and secretion
  127. What is the network of submucosal and myenteric plexuses within the intestines?
    the enteric nervous system

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