Term
| What characterizes the cephalic phase of GI digestion? |
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Definition
| Secretion in mouth due to conditional reflex (pavlov's reflex) or taste of actual food in mouth |
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Term
| What characterizes the gastric phase of GI disgestion? |
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Definition
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Term
| What characterises the intestinal phase of GI digestion? |
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Definition
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Term
| What effect does parasympathetic stimulation have on the rate of GI secretion? |
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Definition
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Term
| What effect does sympathetic stimulation have on GI secretion? |
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Definition
| May slightly increase secretion, but may also counter parasympathetic stimulation and decrease secretion via vasoconstriction and reduction of blood supply |
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Term
| What enzymes are found in saliva? |
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Definition
| Ptyalin (alpha-amylase), lingual lipase, kallikrein |
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Term
| What immunoglobulin is found in saliva? |
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Definition
|
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Term
| How does saliva compare osmotically to plasma? |
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Definition
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Term
| What is the major neural stimulator of salivary secretion? |
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Definition
| Parasympathetic NS, though Sympathetic NS contributes |
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Term
| What effect does aldosterone have on salivary glands? |
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Definition
| Increases K+ secretion, Na+ reabsorption |
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Term
| What are the types of glands in the gastric mucosa of the stomach? |
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Definition
| Oxyntic glands and Pyloric glands |
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Term
| What types of cells make up oxyntic glands? |
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Definition
| Parietal cells, Chief cells, Mucus cells |
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Term
| What kind of cells make up pyloric glands? |
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Definition
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Term
| What do parietal cells secrete? |
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Definition
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Term
| What do chief cells secrete? |
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Definition
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Term
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Definition
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Term
| What is the function of HCl in the GI tract? |
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Definition
| Bactericidal, denatures polypeptides, fascilitates conversion of pepsinogen to pepsin |
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Term
| What is the function of pepsin? |
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Definition
| Initiates protein digestion |
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Term
| What is the purpose of gastric lipase? |
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Definition
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Term
| What is the function of mucus and HCO3? |
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Definition
| Creates the gastric mucosal barrier which protects gastric mucosa, buffers gastric acid |
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Term
| What is the function of intrinsic factor by parietal cells? |
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Definition
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Term
| What is the result of deficient levels of intrinsic factors? |
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Definition
| Low vit B12 absorption leading to pernicious anemia |
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Term
| What enzyme produces H+ and HCO3- in parietal cells? |
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Definition
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Term
| What kind of transporter secretes H+ |
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Definition
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Term
| What stimulates gastric acid secretion? |
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Definition
| AcH, Histamine, Gastrin (stimulates histamine release) |
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Term
| What specific receptor does ACh bind to on parietal cells? |
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Definition
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Term
| What specific receptor does gastrin bind to on parietal cells? |
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Definition
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Term
| What kind of signal transduction do ACh and Gastrin receptors participate in in parietal cells? |
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Definition
| G-protein Gaq activated PLC -> PKC and the release of Ca2+ |
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Term
| What is the specific receptor on parietal cells for Histamines? |
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Definition
| H2 producing cAMP and activating PKA |
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Term
| Which inhibitors oppose the action of histamines on parietal cells? |
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Definition
| Somatostatin and Prostaglandins |
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|
Term
| What nerve directly stimulates parietal cells? |
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Definition
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Term
| Vagal stimulation of what enhances gastric acid secretion through what? |
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Definition
| ECL cells via increased histamine release |
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Term
| Vagal stimulation of what promotes gastric acid secretion by inhibiting the release of what? |
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Definition
| D cells, inhibiting somatostatin release |
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Term
| What stimulates D cells to release somatostatin? What kind of feedback is this? |
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Definition
| Luminal H+, negative feedback |
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Term
| What effect does food have on gastric pH? |
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Definition
| Raises pH due to buffering effect |
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Term
| When are gastric secretions at their highest? |
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Definition
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Term
| Chyme in the duodenum stimulates what? |
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Definition
| Secretin release and enetrogastric reflex |
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Term
| What is the function of secretin? |
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Definition
| Inhibition of gastric acid secretion |
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Term
| What is the function of the enetrogastric reflex |
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Definition
| Inhibits gastric secretion and stomach emptying |
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Term
| What stimulates gastric acid secretion in the stomach? |
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Definition
| Wall distention, presence of digested protein fragments |
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Term
| What is the major stimulus for gastric secretion in the intestines? |
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Definition
| Circulating amino acids are the major stimulus, distention of the intestinal wall is minor stimulus |
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Term
| What stimulates the secretion of pepsinogen? |
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Definition
| ACh, H+ in the stomach lumen, Secretin, Gastrin |
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Term
| What are the functions of the mucus secreted by surface cells in the gastric mucosa? |
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Definition
| Diffusion barrier for H+ and pepsins, also traps HCO3- which titrates any H+ that diffuses into the gel layer from the stomach lumen |
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Term
| What is the result of H+ penetrating the gastric mucosa into the gastric epithelium? |
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Definition
| Damage to mast cells, releasing histamines that trigger an inflammatory response. May lead to injury/ulcers. |
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Term
| What factors contribute to peptic ulcer disease? |
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Definition
| H. Pylori, Aspirin, Bile acids |
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Term
| What is the distribution of exocrine and endocrine cells in the pancreas? |
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Definition
| 90% exocrine, 10% endocrine |
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Term
| What do ductal cells of the pancreas secrete and what are their functions? |
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Definition
| Aqueous component that secretes HCO3-, H2O, and electrolytes, optimizes pH for digestive enzymes and prevents ulceration |
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Term
What do acinar cells of the pancreas secrete and what are their functions?
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Definition
| Enzymatic component, secretes digestive enzymes (amylase, lipase, proteases), aids digestion |
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Term
| What hormones regulate pancreatic secretion? |
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Definition
| Secretin and Cholecystokinin |
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Term
| What stimulates secretin release? |
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Definition
| Acidic chyme in the duodenum |
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Term
| What is the primary effect of secretin? |
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Definition
| Increases HCO3- from pancreatic ductal cells and liver |
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Term
| What stimulates the release of Cholecystokinin? |
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Definition
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Term
| What is the primary effect of Cholecystokinin? |
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Definition
| Increases digestive enzyme secretion |
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Term
| What is the primary neural regulator of pancreatic secretions and what are the effects? |
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Definition
| ACh, stimulated by peptides and amino acids, increases enzyme and aqueous secretions from the pancreas |
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Term
| What type of secondary messengers do ACh and CCk use on pancreatic acinar cells? |
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Definition
| Both utilize G-receptors -> PLC -> PKC and release of Ca2+ |
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Term
| What secondary messengers do VIP and Secretin activate? |
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Definition
| Both use G-protein receptors -> Adenylyl Cyclase -> cAMP -> PKA |
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Term
| What should be kept in mind about dosing patients with CCK? |
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Definition
| High doses are less effective |
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Term
| What electrolyte movement generates HCO3- cotransport? |
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Definition
| Cl- movement out of the cell due to secretin causes favored Na/HCO3 cotransport |
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Term
| What would be the effect of a high protein, low carb diet on pancreatic secretions? |
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Definition
| Increased proportion of proteases, decreased amylase |
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Term
| What is the effect of insulin on the pancreas? |
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Definition
| Maintains normal rates of pancreatic protein synthesis and stores of digestive enzymes |
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