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Gastrointestinal
Anatomy & Physiology: GI
| Question | Answer |
|---|---|
| 1. What is the activity of the components of the muscularis externa ahead of the bolus? 2. Behind the bolus? | 1. Circular muscle relaxed; longitudinal muscle contracted 2. Circular muscle contracted; longitudinal muscle relaxed |
| What is the role of inhibitory neurons in segmenting contractions? | inhibitory neurons are active in the segments that are relaxed and inactive in segments that contract allowing inherent myogenic activity to take place |
| What 2 things stimulate relaxation of the orad stomach? | 1. swallowing center 2. stomach distention initiates long loop vago-vagal reflexes |
| How does the sympathetic NS effect motility, secretions and sphincters in the GI tract? | ↓ motility ↓ secretions ↑ constriction of sphincter |
| How does the parasympathetic NS affect motility and secretions? | ↑ motility ↑ secretions |
| What are the two nerve plexuses in the GI tract and what mucosal layer are they found in? | 1. Meissner's plexus - submucosa 2. myenteric plexus - muscularis externa |
| What are the two layers of muscularis externa? | inner circular outer longitudinal |
| 1. Which substances get absorbed in the stomach? 2. Which substances get absorbed in the large intestine? | 1. alcohol, aspirin, caffeine 2. fluids and ions |
| What are plicae circularis? What are their function? | transverse folds of the mucosa and submucosa in the small intestine that act to increase surface area |
| What is the difference between villi and microvilli? | 1. mucosal folds that form extensions of epithelium 2. microvilli are hair-like extensions of enterocyte plasma membrane |
| What structures act to increase surface area in the small intestine? | 1. plicae circularis 2. villi 3. microvilli |
| What are the taenia coli? What structure do they produce? | 3 distinct bundles of muscle that run longitudinally along the length of the colon; contract to for haustra, or compartments along colon |
| What are the structural differences between the inner and outer surface of the large and small intestine? | 1. small intestine: smooth outer surface, brush border inner surface 2. large intestine: smooth inner surface, haustral bulges on outer surface |
| What forms of sugar is absorbed by the small intestine? | 1. glucose 2. galactose 3. fructose |
| 1. Where and why is salivary amylase inactivated? 2. Sugars ingested are mainly starches and saccharides. What are the different kinds? | 1. in the stomach from high pH 2. starches: amylose and amylopectin; saccharides: sucrose and lactose |
| What are the 3 intestinal enzymes involved in lipid digestion? What cofactors are required for each? | 1. pancreatic lipase - colipase 2. phospholipase A2 - bile acids 3. cholesterol esterase |
| 1. Where are small, medium and large chain fatty acids absorbed in the GI tract? 2. Do medium and long chain fatty acids require micelles for absorption 3. Why or why not? | 1. small = stomach, medium and large = small intestine 2. medium are micelle-independent; their -COOH group is ionized at intestinal pH which increases their hydrophilic character 3. large are micelle-dependent; they are hydrophobic |
| 1. Which macronutrients enter lymphatics after intestinal absorption? 2. Where are other macronutrients absorbed into? | 1. hydrophobic end products 2. hepatic portal vein |
| Which hormone effects Na absorption in the colon? | aldosterone enhances Na/K activity on basolateral membrane and thus activity of ENaC on apical side |
| 1. In the intestine luminal membrane, glucose and galactose are absorbed by __ active transport linked to __. 2. Fructose is absorbed by.. | 1. secondary, sodium 2. facilitated diffusion |
| 1. Small peptides move into the luminal membrane through 2. Enterocytes take up lipids in the form of __ and reform them as __. | 1. PepT1 a Na/H antiporter 2. Micelles, chylomicrons |
| Serous, mucus or mixed? 1. parotid gland 2. submandibular gland 3. sublingual gland | 1. serous 2. mixed 3. mixed |
| 1. Lipid hydrolysis begins in the __. 2. What do goblet cells secrete? What is their function in the stomach? | 1. stomach (lingual lipase) 2. Mucus to protect the stomach mucosa from acid |
| 1. H+ ions are pumped into the stomach lumen via the __ in the parietal cell membrane. 2. Which hormone inhibits acid secretion by binding parietal cells? | 1. K+/H+ ATPase 2. somatostatin |
| 1. Direct path of acid secretion? 2. Indirect path of acid secretion? | 1. ACh, gastrin & histamine stimulate parietal cells 2. ACh & gastrin stimulate histamine release from ECL cells |
| Which GPCR subunit is activated by: 1. ACh 2. Gastrin 3. Histamine | 1. Gaq 2. Gaq 3. Gas |
| Which receptor on the parietal cell is bound by: 1. ACh 2. Gastrin 3. Histamine | 1. M3 2. CCKb 3. H2 |
| Gastrin release is stimulated by: | 1. stomach distention 2. alkalinization of stomach 3. vagal stimulation 4. partially digested proteins 5. hypercalcemia |
| 1. Which hormone inhibits gastrin secretion by binding G cells? 2. Where in the GI tract is gastrin produced. | 1. somatostatin 2. antrum of stomach and duodenum |
| How does gastric inhibitory peptide directly and indirectly reduce acid secretion? | 1. Directly - inhibits parietal cell acid release 2. Indirectly - inhibits gastrin which stimulates H+ release from parietal cells |
| What are the two foms of Gastrin and their main difference | 17 amino acid form is more active than the 34 amino acid form |
| Major effects of gastrin | 1. acid secretion by parietal cells 2. release of histamine by ECL cells 3. pepsinogen secretion by chief cells 4. regulation of mucosal growth in the corpus of the stomach |
| 1. Pepsinogens are secreted by ___ cells. 2. Somatostatin secretion is stimulated by ___. | 1. Chief 2. low gastrin pH |
| Somatostatin has both paracrine and endocrine effects. What makes up the two? | 1. Paracrine - somatostatin from D cells in corpus acts on parietal cells in corpus 2. Endocrine - somatostatin from D cell in the antrum enters bloodstream to parietal cells in corpus |
| 1. CCK is produced by __ cells of the __. 2. What stimulates CCK production? | 1. I cells, duodenum 2. FFA's and amino acids |
| What are the major functions of CCK? | 1. increase in digestive enzyme release from exocrine pancreas acini 2. contracts smooth muscle of gallbladder 3. relaxes Sphincter of Oddi 4. decreases gastric emptying |
| What is the diffeence in CCKa & CCKb receptors in their affinity for hormones? | 1. CCKa binds CCK > gastrin 2. CCKb binds CCK & gastrin equally |
| What is the purpose of colipase? | to displace bile salt form the surface of micelles; required for pancreatic lipase activity |
| 1. Which 2 substances cause pancreatic acinar cell secretion? 2. Which GPCR subunit is activated? | 1. CCK and ACh 2. Gaq |
| 1. Which 2 substances cause pancreatic duct cell secretion? 2. Which GPCR subunit is activated? | 1. Secretin and ACh 2. Gas |
| 1. Which transporter causes HCO3 secretion into the lumen from duct cells? 2. What is produced by F cells of the exocrine pancreas? | 1. Cl/HCO3 exchanger 2. Pancreatic polypeptide |
| Describe the voltage dependent and votage independent mechanism for Cl absorption. | 1. voltage dependent: Cl- passively follows Na uptake 2. voltage independent: Cl/HCO3 exchanger |
| 1. Where are carbohydrates absorbed in the GI tract? 2. Where is lactase located in the GI tract? | 1. small intestine 2. luminal wall of the intestinal epithelium |
| 1. Which section of the GI tract absorbs the largest volume of water? 2. Pancreatic amylase hydrolyzes starch to .... | 1. small intestine 2. maltose and maltotriose |
| In the defecation reflex, how do the internal and external anal sphincters respond to increased stretch in the rectum? | 1. IAS relaxes 2. EAS contracts |
| What is the purpose of the ileal brake? | to slow intestinal transit so absorption can occur |
| What action does the small and large intestine usually take on K+? | 1. small - net absorption 2. large - net secretion |
| What effect does parathyroid hormone have on the intestines? | increased intestinal absorption of calcium |
| 1. What two sources supply blood to the liver 2. Through what does blood leave the liver? | 1. hepatic artery and hepatoic portal vein 2. hepatin vein |
| 1. How does Cl- enter the lumen of a duct? 2. How does Cl- exit the lumen of a duct and enter into a duct cell? | 1. CFTR 2. Cl-/HCO3- exchanger |
| Why is there a biphasic release of insulin? | in the acute phase, preformed insulin is released later, newly synthesized insulin is released |
| 1. Water is absorbed mostly from which portion of the GI tract? 2. Major mechanism of Na+ absorption in the fasted state? | 1. jejunum 2. neutral NaCl absorption |
| What are the 4 mechanisms of Na+ absorption in the GI tract? | 1. Na/nutrient cotransport 2. NaCl uptake 3. ENaC 4. Na/H exchanger |
| The ENaC sodium transporter is located in the __ membrane and coupled to the __ on the opposite membrane. | 1. apical 2. Na⁺/K⁺ exchanger |
| Two main mechanisms of Cl- uptake? | 1. NaCl uptake 2. HCO₃⁻/Cl⁻ exchange |
| Where is intrinsic factor produced | parietal cells of stomach |
| Intrinsic factor binds Vitamin B₁₂ in the __ and is taken up in the __. | 1. duodenum 2. ileum |
| Bile acid synthesis is catalyzed by the action of enzyme __ on cholesterol. | 7-α hydroxylase |
| 1. Where in the GI tract is Meissner's plexus found? 2. Where is the GI tract is Auerback's plexus found? | 1. small intestine to anal canal 2. esophagus to anal canal |
| What effect does CCK have on acid secretion? | CCK deactivates the parietal cells which decreases acid secretion |
| NEW NOTECARDS START HERE********** | |
| Why can ileal resection lead to steatorrhea? | bile is reabsorbed in the ileum and recycled to the liver. ↓ bile → ↓ micelle formation → fat malabsorption. |
| Connects the liver to the anterior abdominal wall. | Falciform ligament |
| 1. Which GI nerve plexus controls motility? 2. Which GI nerve plexus controls secretion and blood flow? | 1. myenteric plexus (Auerbach) 2. submucosal plexus (Meissner's) |
| Distal 1/3 of transverse colon, rectum. 1. blood supply 2. innervation 3. embryonic region | 1. Inferior mesenteric artery 2. Pelvic nerve 3. Hindgut |
| What portion of the intestine contains peyer's patches? | ileum |
| Esophagus, stomach to proximal duodenum, liver, pancreas 1. blood supply 2. innervation 3. embryonic region | 1. celiac 2. vagus 3. foregut |
| Distal duodenum to proximal 2/3 of transverse colon 1. blood supply 2. innervation 3. embryonic region | 1. superior mesenteric artery 2. Vagus nerve 3. Midgut |
| Point at which the common bile duct and pancreatic duct meet. | ampulla of vater |
| 1. valve at the ampulla of vater that allows the release of bile and pancreatic juices 2. What hormones leads to valve opening? | 1. sphincter of oddi 2. cholecystokinin (CCK) |
| What is found within the femoral triangle? | lateral to medial NAVEL 1. Nerve (femoral) 2. Artery (femoral) 3. Vein (femoral) 4. empty space 5. Lymphatic |
| Which structures form the boundaries of the femoral triangle? | SAIL (triangle shaped like a sail) 1. Sartorius muscle 2. Adductor longus muscle 3. Inguinal Ligament |
| What is the TIPS procedure to treat portal hypertension? | Transjugular Intrahepatic Portosystemic Shunt (TIPS) between the portal vein and hepatic vein |
| Which vein drains into the portal system and is responsible for: 1. esophageal varices 2. internal hemorrhoids 3. Caput medusae | 1. left gastric vein 2. superior rectal vein 3. paraumbilical vein |
| What is the pectinate line? | point where the hindgut meets the ectoderm |
| Gastroesophageal junction displaced above the diaphragm. | sliding hiatal hernia |
| Gastroesophageal junction is in the normal place at the level of the diaphram but stomach protrudes through esophageal hiatus. | Paraesophageal hernia - stomach next to esophagus |
| Where are these hormones produced: 1. gastrin 2. cholecystokinin 3. secretin 4. somatostatin | 1. G cells of antrum 2. I cells of duodenum 3. S cells of duodenum 4. D cells of pancreas and GI mucosa |
| What stimulates gastrin secretion? | 1. stomach distention/alkalinization 2. amino acids 3. vagal stimulation |
| What action does gastrin have? | 1. ↑ gastric H+ secretion 2. ↑ growth of gastric mucosa 3. ↑ gastric motility |
| How does atropine effect vagal stimulation of parietal cells and G cells? | 1. No effect on gastrin production 2. blocks stimulation of parietal cells |
| What stimulates CCK release? | fatty acids, amino acids in duodenum |
| What actions does CCK produce? | 1. ↑ pancreatic secretion 2. ↑ gallbladder contraction 3. sphincter of Oddi relaxation 4. ↓ gastric emptying (more time for digestion) |
| What stimulates secretin release? | acid, fatty acids in lumen of duodenum |
| What action does secretin produce? | 1. ↑ pancreatic bicarbonate secretion 2. ↓ gastric H+ secretion |
| Which GI cells produce: 1. gastric acid 2. pepsin 3. bicarbonate | 1. parietal cells of stomach 2. chief cells of stomach 3. mucosal cells along GI tract; Brunner's glands in duodenum |
| Which nerve runs through the parotid gland? | facial nerve (CN VII) |
| What is the vagovagal reflex? | distention of the → vagal afferents to brain → vagal efferents back to stomach → release of vagal neuroendocrines |
| What is the gastroileal reflex | presence of food in the stomach leads to: 1. ↑ peristalsis in the ileum 2. relaxation of the ileocecal sphincter |
| What three factors increase gastric parietal cell acid production? What receptors are involved? | 1. ACh from vagus nerve binds M3 receptor 2. Gastrin from G cells binds CCK type B receptor 3. Histamin from enterochromaffin like cells binds H2 receptor |
| What are the two methods in which gastrin increases gastric acid production? | 1. directly bind parietal cells 2. trigger release of histamine from ECL cells which then bind parietal cells |
| Which G protein subunit do the following act through: 1. prostaglandin 2. Histamine 3. gastrin 4. somatostatin 5. ACh | 1. Gi 2. Gs 3. Gq 4. Gi 5. Gq |
| Converts trypsinogen into the active enzyme trypsin | enterokinase/enteropeptidase |
| Transporters involved: 1. glucose uptake into enterocytes 2. fructose uptake into enterocytes 3. transportation of sugars from enterocyte into blood 4. galactose uptake into enterocyte | 1. SGLT1 (Na+ dependent) 2. GLUT-5 3. GLUT-2 4. SGLT1 |
| Where are the following absorbed: 1. iron 2. folate 3. B12 4. calcium 5. bile | 1. duodenum 2. jejunum 3. ileum 4. duodenum 5. ileum |
| How do triglycerides reach the bloodstream after absorption? | repackaged into chylomicrons within enterocytes → lymph → thoracic duct → bloodstream |
| How does the chloride content of exocrine pancreas secretions change as bicarbonate secretion increases? | Cl decreases as HCO3 increases. They are exchanges for one another by an antiporter |
| 1. Where are lipids digested 2. Where are lipids | 1. duodenum 2. jejunum |
| Name the blood supply of the stomach: 1. proximal lesser curvature 2. distal lesser curvature 3. proximal greater curvature above the splenic artery 4. proximal greater curvature 5. distal greater curvature | 1. left gastric artery 2. right gastric artery 3. short gastric arteries 4. left gastroepiploic 5. right gastroepiploic |
| What is the postprandial alkaline tide and why does it occur? | Increase in plasma bicarbonate after a meal. Gastric parietal cells contain carbonic anhydrase which creates H+ and HCO3-. H+ is secreted into the stomach while HCO3- enters the blood stream. |
| What are the retroperitoneal structures? | 1. duodenum 2. ascending and descending colon 3. kidney, adrenals and ureters 4. pancreas 5. aorta 6. IVS 7. rectum |
| Which inguinal hernia: 1. lateral to the inferior epigastric vessels 2. medial to the inferior epigastric vessels 3. goes through internal and external inguinal ring into scrotum 4. protrudes through inguinal triangle 5. protrudes below inguinal liga | 1. indirect inguinal hernia 2. direct inguinal hernia 3. indirect inguinal hernia 4. direct inguinal hernia 5. femoral hernia |
| In which layer of the GI wall are Brunner's glands located? | submucosa |
| Neonate presents with palpable mass in epigastric region and nonbilious projectile vomiting | Congenital pyloric stenosis |
| Which zone of the hepatocyte is most susceptible to: 1. toxic injury 2. ischemic injury | 1. Zone 1; nearest the portal vein 2. Zone 3; nearest the central vein |
| Where does aldosterone exert it's effect on the GI tract? | colon |
Created by:
amichael87
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