Digestive System

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RUTHCALLAWAY
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267275
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Digestive System
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2014-04-03 21:30:47
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profmwinston
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Digestive System
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  1. Accessory organs
    Salivary glands, liver, gallbladder, pancreas
  2. Extends from the mouth to anus and to several accessory organs.
    alimentary canal
  3. Aliment=
    Food
  4. Functions of the DS
    Mechanical digestion, chemical digestion, ingestion, propulsion, absorption, defecation
  5. mechanical digestion
    breaks food into smaller pieces, not altering chemicals
  6. chemical digestion
    breaks food into simpler chemicals
  7. Innermost layer of alimentary canal. Protects other 3 layers and carries out secretion and absorption
    mucosa (or mucous membrane)
  8. muscular tube about 8 meters long
    alimentary canal
  9. 2nd layer of alimentary canal from the inside. Nourishes surrounding tissues and transports absorbed material
    submucosa
  10. 3rd layer of alimentary canal from the inside, consisting of 2 coats of fibers. Movement of this layer moves contents.
    Muscularis (or muscular layer)
  11. When these fibers of muscular layer contract, the tube diameter decreases
    circular fibers
  12. When these fibers of muscular layer contract, the tube shortens
    longitudinal fibers
  13. Outer layer of alimentary tube. Protects, lubricates.
    Serosa (or serous layer)
  14. Parts of alimentary canal
    mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus
  15. projections of mucosa that increase absorptive surface area
    lumen
  16. Two types of of movement in the alimentary canal
    Mixing and propelling
  17. segmentation
    a type of mixing movement that does not move materials in one direction in the small intestine
  18. Occurs when small segments of the muscular tube contract rhythmically
    mixing movement
  19. Begins when food expands the alimentary canal and causes the sound heard by a stethoscope placed on the abdomen.
    Peristalsis
  20. Waves that move the contents along the canal
    Peristaltic wave
  21. The branch of the ANS that stimulates the digestive process
    PNS 'Rest&Digest'
  22. The branch of the ANS that inhibits the digestive process by stimulating contraction of the sphincter muscles
    SNS 'FightorFlight'
  23. The 2 plexuses involved in controlling the digestive system
    Submucosal and myentric
  24. Where is the submucosal plexus & what does it do?
    Controls secretions by the gastrointestinal tract and is located in the submucosal layer.
  25. Where is the myentric plexus & what is it's function?
    Located in the muscular layer and controls gastrointestinal motility.
  26. Plexus
    Network of interlaced nerves or blood vessels
  27. Receptive relaxation
    The relaxing of the muscular wall just ahead of the ring of contraction involved in peristalsis.
  28. Where digestion begins by breaking up solids and mixing with saliva- Ingestion.
    Mouth
  29. Lymphatic tissue that covers the 'root' of the tongue
    Lingual tonsils
  30. Lymphatic tissue at the back of the mouth on either side that help prevent the body from infection
    Palatine tonsils
  31. Masses of lymphatic tissue on the posterior wall of the pharynx; adenoids.
    Pharyngeal tonsils
  32. What are the 4 types of teeth?
    Incisors, cuspids, bicuspids, molars
  33. What is the diff between primary & secondary teeth?
    Baby teeth and adult teeth; 20 primary, 32 secondary. Primary teeth have no bicuspids.
  34. Incisors are
    Front 4 teeth, upper and lower; for 'biting'.
  35. Cuspids are
    The canine teeth; for 'tearing'.
  36. Bicuspids and molars are
    The flat-surfaced teeth- bicuspids the first 2, and the smaller ones; molars the larger back 3. For 'grinding'.
  37. Name the 3 salivary glands
    Parotid, submandibular, sublingual
  38. Purpose of salivary glands?
    To secrete saliva which protects teeth from acids in food, dissolves food so you taste, and helps cleanse mouth/teeth.
  39. Location and secretion of parotid gland
    Parotid gland- largest; located anterior and inferior to ears. Serous cells- clear fluid rich in salivary amylase.
  40. Location & secretion of submandibular glands
    Located on inside surface of lower jaw. Cells  are equally serous & mucous.
  41. Two types of secretory cells?
    Serous- watery fluid containing digestive enzyme salivary amylase . Mucous- thick liquid which binds food&lubricates swallowing.
  42. What does salivary amylase 'digest'?
    Splits starches & glycerin into disaccharides, the first step in chemical digestion of carbs.
  43. What effect does SNS&PNS have on salivary glands?
    • SNS- dries up glands (fightorflight); SNS stimulated by unpleasant sight, smell, taste of food. 
    • PNS- stimulates glands (rest&DIGEST); PNS stimulated by sight, smell, taste,& thought, of good food!
  44. Location & secretion of sublingual gland
    Smallest; On floor of mouth inferior to tongue. Primarily mucous secretion.
  45. The 2 sphincters that control what enters and passes thro the stomach?
    • Lower esophageal sphincter (or cardiac sphincter) is the entrance to stomach. 
    • Pyloric sphincter is the entrance to the duodenum/small intestine.
  46. How is the structure of the stomach specialized to allow it to conduct its function?
    Stomach folds w ability to expand an secretory action of cells in stomach mucosa
  47. Main digestive function of stomach?
    Produce gastric juices. Also absorbs some water and salts.
  48. Propulsion starts here.
    Pharynx
  49. Mixes food w gastric juices & initiates the digestion of proteins
    Stomach
  50. Located at the end of gastric glands & secrete gastric juices
    Gastric pits
  51. Most important digestive enzyme in gastric juices
    Pepsin
  52. Pepsinogen
    Secreted by chief cells of gastric glands; contacts hydrochloric acid from parietal cells & forms pepsin.
  53. What is a chief cell?
    Cell type found in gastric gland that secretes digestive enzyme pepsin.
  54. List the 3 types secretory cells in the stomach
    • Mucous cells
    • Chief cells(peptic) which secrete digestive enzymes
    • Parietal cells which secrete hydrochloric acid
  55. What forms gastric juice?
    Product of mucous, chief, parietal cells.
  56. Mucous cells
    Provide an alkaline protective layer.
  57. Parietal cells
    Provide acidic environment for production & action of pepsin.
  58. Intrinsic factor are secreted by_______ and is required for?
    Secreted by parietal cells of gastric glands and is required for vitB12 absorption from small intestine.
  59. What is chyme?
    Mixed food particles & gastric juices in stomach
  60. 3 stages of gastric secretion?
    • Cephalic phase
    • Gastric phase
    • Intestinal phase
  61. 2 digestive reflexes & their functions
    • Enterogastric reflex: controls chyme rate of entering SI
    •  
    • Vomiting reflex
  62. The three triggers of the cephalic stage:
    Sight, smell, & thought!
  63. What hormone inhibits the digestive process and how?
    Somatostatin, by inhibiting the release of gastrin.
  64. What effect does SNS & PNS have on production and release of somatostatin?
    PNS suppresses somatostatin so gastrin can be released. SNS stimulates somatostatin.
  65. Which hormone activates the digestive process & how?
    Gastrin, by increasing the secretory activity of gastric glands.
  66. ATCH stimulates what cells?
    Cells of the gastric glands. Also suppresses the hormone somatostatin.
  67. Who secretes somatostatin?
    Specialized cells closely associated with parietal cells(which secrete hydrochloric acid). SNS stimulates.
  68. The 4 triggers of the intestinal stage:
    Stretch, proteins, lipids, acidic pH
  69. The 3 triggers of the gastric stage:
    Stretch of stomach lining, protein, increased(or alkalinic) pH
  70. 3 chemicals released in gastric stage in response to triggers of stretch, protein, increased pH, and their effect?
    Histamine, ACh, gastrin-each stimulate gastric juice secretion.
  71. Cephalic phase..
    Begins when PNS inhibits somatostatin secretion which releases gastrin -stimulating gastric glands- thro thought, smell, sight & taste.
  72. Explain the alkalinic tide.
    For the stomach to produce hydrochloric acid, H+ ions are removed from the blood. The same # of alkalinic HCO3 is released into the blood. After a meal, blood HCO3 increases & urine excretes excess.
  73. Gastric phase starts..
    When food enters the stomach.
  74. How does hormone cholecystokinen effect somach motility and what triggers it?
    (CCK) Decreases gastric motility. Triggered by fats/proteins in SI.
  75. Most nutrients are absorbed in
    The small intestine.
  76. What type of food moves quickest thro stomach?
    Liquids, foods high in protein, carbs.
  77. What type of food moves slowly thro the stomach?
    Solids: fatty foods.
  78. What stimulates the hormone gastrin?
    PNS impulses inhibit somatostatin and stimulate certain stomach cells in the pyloric region to release the hormone gastrin, which increases secretory activity of gastric glands.
  79. Which hormone is triggered by low or acidic pH? and what is its effect?
    Secretin. It is released into the blood from the duodenal mucous membrane in response to acidic  chyme in SI. It stimulates pancreas to release PJ high in HCO3.
  80. Describe enterogastric reflex.
    Starts in sm intestine(intero), ends in stomach(gastric). Chyme fills duodenum. Stretch receptors slow PNS impulse. As a result, peristalsis is inhibited, slowing intestinal filling and regulating how fast chyme leaves the stomach.
  81. What is the result of secretin release and why is it important?
    Secretin stimulates the release of PJ which is rich in bicarbs. The bicarbonate ions neutralize(alkaline) the acidic chyme so that the action of digestive enzymes can function.
  82. Function of pancreatic amylase:
    Splits carbs into dissacharides.
  83. Function of pancreatic trypsin, chymotrypsin, carboxypeptidase:
    Protein-splitting(proteolytic) enzymes.
  84. Function of pancreatic nucleases:
    Breaks nucleic acids into nucleotides.
  85. Function of pancreatic lipase:
    Breaks tryglycerides into fatty acids & monoglycerides.
  86. Pancreatic juices digest:
    Carbs, fats, proteins, nucleic acids.
  87. The 6 major pancreatic enzymes found in pancreatic juice:
    • 1)Amylase(carbs)
    • 2)Lipase(fat)
    • 3)Nucleases(nucleic acid)
    • 4)Trypsin                  }
    • 5)Chymotrypsin          }(proteins)
    • 6)Carboxypeptidase   }
  88. The function of zymogen granules?
    Stores proteolytic(protein-splitting) enzymes, which are secreted in inactive forms & activated by enterokinase, after they reach the sm intestine.
  89. Actions of trypsin:
    • Turns: chymotrypsinogen to chymotrypsin
    •         :procarboxypeptidase to carboxypeptidase.
  90. Function of enterokinase and where the action happens?
    Activates trypsinogen to trypsin- which in turn activates chymotrypsin and carboxypeptidase.All are protein-splitting enzymes secreted in inactive forms from the pancreas' zymogen granules into SI where they encounter enterokinase.
  91. The 2 hormones that control pancreas secretion, their triggers and their effects:
    • Secretin: Triggered by acidic chyme in duodenum. Stimulates pancreatic secretion high in bicarbonate ions to neutralize acid in duodenum.  
    • Cholycystokinin(CCK): Triggered by proteins and fats in duodenum and stimulates a pancreatic juice high in digestive enzymes.
  92. 2 actions of bicarb important to DS:
    • 1)Alkalinic(high in bicarbs, low in H+) pancreatic juice provides the alkalinic environment needed for the actions of digestive enzymes. 
    • 2)An alkaline environment in SI blocks pepsin action and damage to duodenum.
  93. Pancreatic juice contains enzymes that digest:
    Carbs, fats, proteins, and nucleic acid.
  94. Monoglyceride:
    One fatty acid bound to glycerol.
  95. Largest internal organ and what it does:
    Liver; much metabolic activity, most importantly protein. Stores many substances including iron, vits A, D, B12. Detoxifies. Role in digestion is to secrete bile.
  96. Path of bile from bili canaliculus to SI, naming all vessels and sphincters.
    Bile canaliculi, bile ductile, L or R hepatic duct, common hepatic duct, bile duct, hepatopancreatic sphincter.
  97. What is the main digestive function of the liver?
    To secrete bile.
  98. What function does bile perform?
    Bile salts break down fats. Lack of bile salts results in poor lipid reabsorption & vit deficiencies.
  99. Define emulsification.
    Bile salts breaking fat globules into fat droplets! :0! Droplets can then mix with water and be digested more effectively.
  100. The function of Kupferr cells and where they are located?
    Large cells in the lining of hepatic sinusoids that remove most of bacteria from the blood by phagocytosis.
  101. What is the function of the gall bladder?
    Stores bile, concentrates bile by reabsorbing water, contracts to release bile.
  102. What are gallstones and how do they form?
    Bile becomes concentrated in gallbladder d/t water and electrolyte reabsorption. If cholesterol is separated from bile composition, it forms gallstones.
  103. 7 main functions of liver:
    • 1)Carb     }
    • 2)Lipid       }metabolism
    • 3)Protein  }
    • 4)Glycogen and vitamin storage
    • 5)Blood filtering
    • 6)Detoxification
    • 7)Secretion of bile
  104. Carb metabolism by liver helps maintain:
    Glucose levels.
  105. Lipid metabolism by liver produces:
    Fats which are transported to adipose tissue for storage.
  106. Protein metabolism by liver is:
    Most vital function. Forms urea, clotting factors and more.
  107. Liver storage includes
    Many substances including glycogen, iron, vits A, D, B12, & blood.
  108. Liver blood filtering removes:
    Damaged red blood cells and foreign substances by phagocytotic Kupferr cells.
  109. What effect does CCK have on the gallbladder?
    Contraction, & release of bile/opens the sphincter of Oddi.
  110. What is the hormone CCK released in response to?
    Proteins and fats in the SI.
  111. What effect does CCK have on the pancreas?
    Stimulates pancreatic enzyme secretion of fluid with high digestive enzyme.
  112. What causes the hepatopancreatic sphincter(sphincter of Oddi) to open?
    Cholecystokinen
  113. 3 general areas of the small intestine(SI)?
    Duodenum, jejunum, ileum.
  114. Main digestive function of SI?
    To absorb the products of digestion.
  115. How is the mucosa of the SI specialized to support it's function?
    Increased surface layer due to plicae circularis of mucosa, villa, an microvilla.
  116. How does each speciliazed structure of SI support absorption?
    Mucous is secreted, causing surface area to flow together and be increased; hairs of villa/microvilla also increase surface area.
  117. List the major enzymes embedded in the membranes of the microvilla of the SI?
    • Peptidases: split peptides
    • Sucrase, maltese, lactase: split to monosaccharides
    • Intestinal lipase: splits fat into fatty acids&glycerol
  118. Describe mesentery.
    The double layered fold of peritoneum that suspends the jejunum and ileum from the abdominal wall. Also supports cardiovascular system to intestinal wall.
  119. What is peristaltic rush?
    Overdistended or irritated SI wall causes a strong peristaltic rush to pass along the length of the tube, sweeping contents into LI so quickly that water, electrolytes, & nutrients are not absorbed, ie: diarrhea!
  120. Intestinal villi are:
    Tiny projection of mucous membrane in SI, increasing SI surface area & thus absorption.
  121. Intestinal microvilli are:
    Tiny brush-like extensions of intestinal villa that continue to increase area/reabsorption!
  122. Plicae circularis are:
    Circular folds of mucosa in the lining of the SI and increase the surface area for absorption.
  123. The 2 main functions of the large intestine?
    • 1) Absorb water and electrolytes
    • 2) Form & store feces
  124. How is the mucosa of the LI specialized to support it's function?
    No plicae circularis & no villa, but has goblet cells which secrete mucous.
  125. 2 major changes in the gross anatomy of LI compared to rest of alimentary canal:
    • 1)Tenia coli: Longitudinal fibers in 3 distinct bands that extend the length of the colon.
    • 2)Haustra: When the bands exert tension lengthwise on the wall, a series of pouches(haustra) are created.
  126. Define mass movements.
    Peristaltic wave in the LI happen only 2 to 3 tmes daily, compared to those of the SI  that occur frequently. These waves in the LI produce mass movements in which a large section of wall constricts vigorously, forcing contents down LI.
  127. Describe the defecation reflex.
    As the rectum walls extend, the defecation reflex is triggered, which in turn triggers peristaltic waves in the descending colon. The internal involuntary sphincter relaxes. Abdominal muscles increase pressure on the rectum. The external sphincter muscle is signaled to relax.
  128. The 4 main parts of LI?
    • 1)Cecum
    • 2)Colon
    • 3)Rectum
    • 4)Anal canal
  129. Describe the appendix?
    Near the opening of the LI, hangs a narrow tube w a closed end. Contains lymphatic tissue, but has no known digestive function.
  130. Enterokinase is secreted by:
    The mucosa of the SI.
  131. The first action of the PNS in digestion?
    To inhibit somatostatin secretion by parietal cells so that gastrin flows uninhibited.
  132. The hormone histamine is released by? and what is it's effect?
    PNS impulses AND gastrin promote release of histamine from mucous cells, stimulating more gastric secretion.
  133. Enzyme:
    A substance that acts as a catalyst to bring about a specific biochemical reaction.
  134. Liver detoxification:
    Breaks down toxins.
  135. Liver secretes___ and why is it important?
    Bile, which contain bile salts to break down fats.
  136. Function of gallbladder besides storage?
    Reabsorbs water and electrolytes and concentrates bile. Cholesterol normally remains in bile solution.
  137. Bile contains:
    Water, bile salts, bile pigments, cholesterol & electrolytes.
  138. What bile substance is most abundant and what does it do?
    Bile salts; they are the only bile substance with a digestive function.
  139. What do hepatic cells use to produce bile salts?
    Cholesterol! which has no special function in bile or digestion. Altho in releasing bile salts, hepatic cells also release some cholesterol into bile.
  140. What purpose do the goblet cells of the LI serve?
    Alkalines the LI contents, assists to form feces, protects intestinal wall against abrasion.

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