Ch.26

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Sunni7
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195616
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Ch.26
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2013-01-27 19:20:05
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Physiology Digestive System
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  1. What system is muscular but needs endocrine and exocrine for digestive enzymes?
    GI system
  2. Ingestion:
    food is taken in
  3. Digestion:
    breakdown of complex nutrients into simple nutrients
  4. Motility of the gastrointestinal (GI) wall:
    physically breaks down large chunks of food material and moves food along the tract
  5. Secretion of digestive enzymes allows:
    chemical digestion
  6. Absorption:
    movement of nutrients through the GI mucosa into the internal environment
  7. Elimination:
    Happens where?
    excretion of material that is not absorbed; large intestine
  8. Regulation:
    coordiantion of the various functions of the digestive system
  9. The digestive tract is functionally an extension of the ______ environment; material does not truly enter the body until it is absorbed into the ______ environment.
    external; internal
  10. Change ingested food from large particles into minute particles, facilitating:
    chemical digestion
  11. Churn contents of the GI lumen to mix with digestive juices and come in contact with the surface of the _______ _______, facilitating ______.
    intestinal mucosa; absorption
  12. Propel food along the _________ tract, eliminating digestive waste from the body.
    alimentary
  13. What does mastication do?
    • chewing movements
    • reduces size of food particles
    • mixes food with salvia in preparation for swallowing
  14. What does aspirate mean?
    food is in the lungs
  15. Deglutition:
    process of swallowing; complex process requiring coordination, rapid movements
  16. Oral stage:
    (mouth to oropharynx) voluntarily controlled
  17. Pharyngeal stage:
    (oropharynx to esophagus) involuntary movement
  18. Esophageal stage:
    (esophagus to stomach) involuntary movement
  19. Describe the stages of swallowing OPE:
    Oral- food in the middle of the tongue presses against palate & it moves to the oropharynx

    Pharyngeal- so food goes from pharynx to esophagus, mouth, nasopharynx & larynx blocked. Then contractions and gravity move it.

    Esophageal- contractions & gravity move bolus through esophagus & into stomach
  20. Wavelike ripple of the muscle layer of a hollow organ:
    Peristalsis
  21. Progressive motility that produces forward movement of matter along the GI tract:
    Peristalsis
  22. Mixing movement; digestive reflexes cuase a forward-and-backward movement with a single segment of the GI tract:
    Segmentation
  23. Helps breakdown food particles, mixes food with digestive juices, & brings digested food in contact with intestinal mucosa to facilitate absorption:
    Segmentation
  24. Gastric motility: _ to _ hours to empty the stomach; in the stomach food is chruned (propulsion & retropulsion) & mixed with gastric juices to form _____. Which is ejected into the duodenum every ___ ______.
    • 2 to 6 hours
    • chyme
    • 20 seconds
  25. Gastric emptying is controlled by:
    hormonal & nervous mechanisms
  26. ________ _________: fats in duodenum stimulate the release of gastric inhibitory peptide, which decreases peristalsis of gastric muscle and slows passage of chyme into duodenum.
    Hormonal mechanism
  27. _______ _______: enterogastric relex; receptors in the duodenal mucosa are sensitive to presence of acid and distention; impluses over sensory and motor fibers in the ______ nerve cause a reflex inhibitation of gastric peristalsis.
    Nervous mechanism; vagus nerve
  28. Intestinal motility: Segmentation in duodenum and upper jejunum mixes with digestive juices from the:

    *hint 3 things
    • pancreas
    • liver
    • intestinal mucosa
  29. Intestinal motility: Rate of peristalsis picks up as chyme approaches end of ______, moving it through the rest of the small intestine into the large intestine.
    Jejunum
  30. After leaving stomach, chyme normally takes approximately __ _____ to pass through the small intestine.
    5 hours
  31. _______: regulated in part by intrinsic stretch reflexes; stimulated by cholecystokinin (___).
    Peristalsis; (CCK)
  32. Absorption threw villi & microvilli in the small intestine absorbe the:
    chyme
  33. _______: changes in chemical composition of food as it travels through the digestive tract; these changes are the result of _____.
    Chemical digestion; hydrolysis
  34. What are digestive enzymes?
    Extracellular, organic (protein) catalysts.
  35. Specific in their actions
    Function at a specific pH & temperature
    Most catalyze a chemical reaction in both directions
    Principles of enzyme action
  36. What is continually being destroyed or eliminated from the body and must continually be synthesized?
    Enzymes
  37. Most digestive enzymes are synthesized as ______ ______.
    inactive proenzymes
  38. What type of compouds are carbohydrates?
    saccharide compounds
  39. What is hydrolyzed by amylase? What does it form?
    Polysaccharides; forms disaccharides
  40. Final steps of carbohydrate digestion are catalyzed by what? *Hint: These are found in the cell membrane of epithelial cells covering the villi that line the intestinal lumen.
    • sucrase
    • lactase
    • maltase
  41. What are proteins compounds composed of?
    twisted chains of amino acids
  42. What catalyzes hydrolysis of proteins into intermediate compounds and, finally, amino acids?
    Proteases
  43. Main proteases:
    _____ in gastric juice.
    _____ in pancreatic juice.
    _____ in intestinal brush border.
    • Pepsin in GJ
    • Trypsin in PJ
    • Peptidases in IBB
  44. Breakdown proteins with _____ which make _____ _____ which make cell walls.
    proteases; amino acids
  45. What must be emulsified by bile in small intestine before being digested?
    Fats
  46. What is the main fat-digesting enzyme?
    Pancreatic lipase
  47. _____ __ ______: some compounds of food resist digestion and are eliminated as feces.
    Residues of digestion
  48. Fats are not absorbed very well in general so they have to be coated. What is formed to maintain cell walls?
    Glycerall
  49. Saliva is secreted by:
    salivary glands
  50. What lubricates food and, with water, facilitates mixing?
    mucus
  51. What enzyme begins the digestion of starches; a small amount of salivary lipase is released its function uncertain.
    Amylase
  52. What increases the pH for optimal amylase function and is necessary to maintain pH?
    Sodium bicarbonate
  53. What is secreted by gastric glands?
    gastric juice
  54. Pepsin is a protease that begin the digestion of proteins. It is secreted as what by what type of cells?
    it is secreted as inactive pepsinogen by cheif cells
  55. What is secreted by parietal cells?
    hydrochloric acid
  56. What decreases the pH of chyme for activation & optimal function of pepsin?
    hydrochloric acid
  57. What is released actively into the gastric juice by hydrogen-potassium pumps (proton pumps)?
    hydrochloric acid
  58. Vesicles in the resting parietal cell move to the apical surface when the cell becomes active, thus increasing the surface area for the process of secretion:
    hydrochloric acid
  59. (secreted by parietal cells) protects vitamin B12, and later facilitates its absorption:
    Intrinsic factor
  60. Mucus and water lubricate, protectm and facilitate mixing of chyme:
    Intrinsic factor
  61. What takes B12 & attches it to its self to be absorbed?
    Intrinsic factor
  62. Pancreatic juice: secreted by ____ and ____ cells of the pancreas.
    acinar; duct
  63. Proteases (e.g. trypsin & chymotrypsin) are enzymes that digest _____ and _____.
    proteins and polypeptides
  64. Lipases are enzymes that digest:
    emulsified fats
  65. Nucleases are enzymes that digest:
    nucleic acids such as DNA & RNA
  66. Amylase is an enzyme that digests:
    starches
  67. What is secreted by the liver; stored & concentrated in the gallbladder?
    bile
  68. Lecithin & bile salts emulsify fats by encasing them in shells to form tiny spheres called what?
    micelles
  69. What increases pH for optimal enzyme function?
    sodium bicarbonate
  70. ______, products of detoxification, and bile ______ (e.g. bilirubin) are wast products excreted by the liver and eventually eliminated in the feces.
    Cholesterol; bile pigments
  71. What is secreted by cells of intestinal exocrine cells?
    Intestinal juice
  72. Mucus and water lubricate and aid in continued mixing of chyme:
    Intestinal juice
  73. Only reflex mechanisms control the secretion of saliva.
    Chemical and mechanical stimuli come from the presence of food in the mouth.
    Olfactory and visual stimuli come from the smell and sight of food.
    Salivary secretion
  74. What is stimulated by several hormones released by intestinal mucosa?
    Pancreatic secretion
  75. Pancreatic secretion evokes production of pancreatic fluid low in enzyme content but high in what?
    bicarbonate
  76. Causes increased exocrine secretion from the pancreas.
    Opposes gastrin, thus inhibiting hydrochloric acid secretion.
    Stimulates contraction of the gallbladder so that bile is ejected into the duodenum.
    CCK
  77. Bile secreted continually by the liver; secretin and CCK stimulate ejection of bile from the gallbladder:
    bile secretion
  78. Little is known about the regulation of this; suggested that the intestinal mucosa is stimulated to release hormones that increase the production of intestinal juice.
    Intestinal secretion
  79. What is the process of absorption? It is a complex system and the majority happens where?
    • Passage of substances through the intestinal mucosa into the blood or lymph.
    • Most absorption occurs in the small intestine, in the duodenum part.
  80. Lymph empties into vena cava fats ect. to help maintain what?
    protein levels
  81. _______: the expulsion of feces from the digestive tract; act of expelling feces is called _____.
    elimination; defecation
  82. What occurs as a result of a reflex brought about by stimulation of receptors nin the rectal mucosa that is produced when the rectum is distended?
    Defecation
  83. _______: contents of the lower part of the colon & rectum move at a slower than normal rate; extra water is absorbed from the feces, resulting in a hardened stool.
    Constipation
  84. ________: result of increased motility of the small intestine, causing decreased absorption of water & electrolytes & a watery stool.
    Diarrhea
  85. Primary contribution of the digestive system to overall homeostasis is to provide what?
    A constant nutrient concentration in the internal environment
  86. Secondary roles of digestive system:
    1. Absorption of _____.
    2. Teeth & tongue, along with _____ & _____ system, are important in producing spoken language.
    3. _____ _____ help the immune system by destroying potentially harmful bacteria.
    • 1. Nutrients
    • 2. Resipratory & Nervous
    • 3. Gastric acids
  87. Regulation of digestive motility and secretion requires the ______ system and _____ system.
    Nervous & Endocrine
  88. Oxygen for digestive activity depends of proper functioning of the ______ and ______ systems.
    Respiratory & Circulatory
  89. ________ and _______ systems support & protect the digestive organs.
    Integumentary & Skeletal
  90. _______ system is needed for ingestion, mastication, deglutition, and defecation to occur normally.
    Muscular
  91. To accomplish its functions, the digestive system needs other system contributions. What other systems are needed?
    • Nervous
    • Endocrine
    • Respiratory
    • Circulatory
    • Integumentary
    • Skeletal
    • Muscular

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