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32 Cards in this Set
- Front
- Back
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55. Effect of NO in GI?
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a. Increases smooth muscle relaxation, including lower esophageal sphincter.
b. Loss of NO secretion is implicated in increased lower esophageal tone of achalasia. |
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56. Where is Motilin secreted?
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a. Cells of small intestine.
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57. Action of Motilin and What regulates (increases or decreases)?
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a. Produces migrating motor complexes (MMCs).
b. Increased in fasting state. c. Motilin receptor agonists are used to stimulate intestinal peristalsis. |
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58. What cells secrete intrinsic factor?
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a. Parietal cells of stomach.
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59. Action of Intrinsic factor?
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a. Vitamin B12 binding protein (required for B12 uptake in terminal ileum).
b. Autoimmune destruction of parietal cells->chronic gastritis and pernicious anaemia. |
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60. What cells secrete HCL?
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a. Parietal cells.
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61. What regulates (increases or decreases) Gastric acid (HCL)?
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a. Increased by histamine, ACh, Gastrin.
b. Decreased by somatostatin, GIP, Prostaglandin, secretin. |
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62. Gastrinoma?
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a. Gastrin-secreting tumour that causes continuous high levels of acid secretion and ulcers.
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63. What cells secrete Pepsin?
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a. Chief cells.
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64. Function and regulation of Pepsin?
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a. Protein digestion.
b. Increased by vagal stimulation and local acid. c. Inactive pepsinogen is cleaved to Pepsin by H+. |
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65. What cells secrete HCO3?
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a. Mucosal cells
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66. Saliva type from Parotids?
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a. Mostly serous.
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67. Saliva type from submandibular and sublingual?
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a. Mostly Mucinous.
b. “Serous on the Sides (Parotids), Mucinous in the Middle (sublingual)”. |
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68. Components and function of salivary secretion?
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a. α-amylase (ptyalin) begins starch digestion; inactivated by low pH on reaching stomach.
b. Bicarb-neutralizes oral bacterial acids, maintains dental health. c. Mucins (glycoproteins- lubricate food. d. Antibacterial secretory products e. Growth factors that promote epithelial renewal. |
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69. What is salivary secretion stimulated by?
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a. Both sympathetic (T1-T3 superior cervical ganglion and parasympathetic (facial, glossopharyngeal nerve) activity.
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70. Effect of low flow rate on salivary secretion?
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a. Hypotonic secretion (More time to reabsorb Na and Cl)
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71. High flow rate on salivary secretion?
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a. Closer to isotonic (less time to reabsorb Na and Cl).
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72. What nerve runs through the parotid gland?
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a. CN VII.
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73. Function of Brunner glands in the duodenum?
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a. Secrete alkaline mucus to neutralize acid contents entering the duodenum from the stomach.
b. Located in the duodenal submucosa (the only GI submucosal glands). c. Hypertrophy of Brunner’s glands is seen in peptic ulcer disease. |
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74. Pancreatic α-amylase?
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a. Starch digestion, secreted in active form.
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75. Pancreatic enzymes for fat digestion?
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1. Lipase
2. Phospholipase A 3. Colipase. |
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76. Pancreatic proenzymes (zymogens)?
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a. Proteases:
1. Trypsin, chymotrypsin, elastase, carboxypeptidases |
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77. Trypsinogen?
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a. Converted to active enzyme trypsin by enterokinase/enteropeptidase, an enzyme secreted from duodenal mucosa.
b. Trypsin activates other proenzymes and more trypsinogen (positive feedback loop). |
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78. Salivary amylase?
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a. Starts digestion.
b. Hydrolyzed α-1,4 linkages to yield disaccharides (maltose and α-limit dextrins). |
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79. Where is pancreatic amylase in highest concentration and function?
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a. Highest concentration in duodenal lumen.
b. Hydrolyses starch to oligosaccharides and disaccharides. |
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80. Where are oligosaccharide hydrolases and function?
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a. At brush border of intestine, the rate-limiting step in carbohydrate digestion, produce monosaccharides from oligo and disaccharides.
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81. Carbohydrate absorption?
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a. Only Monosaccharides (glucose, galactose, fructose) are absorbed by enterocytes.
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82. What are glucose and galactose taken up by?
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a. SGLT1 (Na+ dependent).
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83. How is fructose taken up?
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a. Facilitated diffusion by GLUT-5.
b. All monosaccharides. transported to blood by GLUT-2. |
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84. Where and in what form is Iron absorbed?
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a. As Fe2+ in duodenum.
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85. Where is Folate absorbed?
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a. Jejunum.
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86. Where is B12 absorbed?
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a. Ileum a w/bile acids. Requires intrinsic factor.
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