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29 Cards in this Set
- Front
- Back
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how is salivary secretion stimulated?
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by sympathetics (T1-T3 superior cervical ganglion) and parasympathetics (facial and glossopharyngeal)
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what are the 3 functions of salivary secretions from the parotid, submandibular, and sublingual glands?
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1. alpha amylase for starch digestion
2. bicarb to neutralize oral bacterial acids and dental health 3. mucins (glycoproteins) to lubricate food |
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source and action of gastrin?
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G cells of stomach antrum
increase HCl production and proliferation of gastic mucosa |
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how is gastrin secretion regulated? what 2 aa's are very potent stimulators of gastrin?
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regulation:
1. increase: stomach distention, amino acids, peptides, vagal stimulation 2. decrease: acid secretion, pH < 1.5 phenylalanine and tryptophan are potent stimulators |
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source and action of CCK (cholecystokinin)?
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source: I cells of duodenum and jejunum
axn: increase pancreatic secretions, stimulate gallbladder contraction, inhibit gastric emptying |
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why does pain worsen in cholelithiasis after fatty food ingestion?
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CCK secretion promotes gall bladder contraction
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regulation of CCK?
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decrease: secretin and stomach pH < 1.5
increase: fatty acids and amino acids |
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source and axn of secretin?
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source: S cells of duodenum
axn: increase pancreatic HCO3- secretion and inhibits gastrin secretion |
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stimulation of secretin secretion? purpose of secretin?
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stimulated by acid, fatty acids in lumen of duodenum
bicarb neutralizes acid in duodenum to let pancreatic enzymes to work |
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source and axn of somatostatin?
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source: D cells in pancreatic islet cells, GI mucosa
axn: inhibition of... 1. gastric acid and pepsinogen secretion 2. pancreatic and small bowel fluid secretion 3. gallbladder contraction 4. release of both insulin and glucagon |
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regulation of somatostatin?
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increased by acid and decreased by vagus
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general purpose of somatostatin in GI?
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inhibitory hormone: anti-growth hormone effects (digestion and absorption of substances needed for growth)
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source and axn of gastric inhibitory peptide (GIP)?
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source: K cells of duodenum and jejunum
axn: exocrine (lower gastric HCl secretion); endocrine (increase insulin release) |
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source and axn of intrinsic factor?
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source: parietal cells of stomach
axn: vitamin B12 binding |
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what happens in the autoimmune destruction of parietal cells?
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less intrinsic factor -> chronic gastritis and pernicious anemia
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source and axn of gastric acid?
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source: parietal cells of stomach
axn: lower stomach pH |
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regulation of gastric acid secretion?
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increase: histamine, ACh, gastrin
decrease: somatostatin, GIP, prostaglandin |
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source and axn of pepsin?
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source: chief cells of stomach
axn: protein digestion, optimal axn at pH 1-3 |
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regulation of pepsin?
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increased by vagal input and acid
acid converts pepsinogen -> pepsin |
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bicarb source and function?
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source: mucosal cells, stomach and duodenum
axn: neutralize acid and prevent autodigestion |
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what stimulates bicarb secretion?
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secretin
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what parts of the GI system are retroperitoneal? what is partially peritonealized?
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duodenum, body and head of pancreas, esophagus
partial: ascending and descending colons, tail of pancreas |
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source and axn of VIP (vasoactive intestinal peptide)?
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source: smooth muscle and nerves of intestines
axn: relaxes intestinal smooth muscle, causes pancreatic bicarb secretion and block gastric acid secretion |
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what parts of GI are completely peritonealized?
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liver, stomach, transverse and terminal colons, and cecum
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what enzyme converts pancreatic trypsinogen to active form? what does trypsin do?
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enterokinase, a duodenal brushborder enzyme
activates other proenzymes and activates trypsinogen (positive feedback loop) |
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what are 4 pancreatic proteases?
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trypsin
chymotrypsin elastase carboxypeptidase |
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what types of carbohydrates are absorbed?
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monosaccharides only: glucose, galactose and fructose
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what does bacterial colon do to direct bilirubin?
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converts to urobilinogen and then stercobilin is excreted in feces
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what side of the hepatocytes face the bile canaliculi?
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ABC!
Apical surface faces Bile Canaliculi basolateral faces liver sinusoids |
