Small Intestine Disorders PDF

Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c the most striking gross structural features of the small intestines villi are =...

Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c the most striking gross structural features of the small intestines villi are = Series of electrical activity patterns in the smooth muscle of the gastrointestinal tract What are migrating myoelectric complexes? How does feeding affect migrating myoelectric complexes? Disrupts them, inducing segmentation and peristaltic contractions 1. bacteria polymers broken down by = 2. amylase 1. glucose polymers broken down to = 2. galactose what absorbs glucose and galactose? 1. SGLT-1 with 2 Na+ ions fructose passes by = facilitated diffusion Which transporter is responsible for the absorption of glucose, SGLT1 galactose, and Na+ ions in enterocytes? What process drives the absorption of glucose and galactose Extrusion of Na+ by Na+-K+ ATPase against their concentration gradients? How is the electrochemical Na+ gradient created for nutrient ab- Na+-K+ ATPase pumping Na+ out of the basolateral membrane sorption? Facilitated diffusion through the apical membrane by GLUT-5 How is fructose absorbed into the cell? transporter Which transporter is responsible for fructose absorption into the GLUT-5 cell? all three hexoses leave the cell by facilitated diffusion through = GLUT-2 GLUT-2 located in the = basolateral membrane What symptom can arise from lactase deficiency? Osmotic diarrhea following the consumption of lactose-rich foods Where are disaccharidases, including lactase, located in the in- In the apical brush border membrane of villous absorptive epithe- testine? lial cells A rare autosomal recessive disorder caused by mutations in the gene encoding lactase. What is congenital lactase deficiency? 1. congenital What are the 3 types of lactase deficiency? 2. acquired 3. transient 1. Explosive diarrhea with watery, frothy stools What are the symptoms of congenital lactase deficiency? 2. Abdominal distention after milk ingestion. 1 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c How can symptoms of congenital lactase deficiency be alleviated? By terminating exposure to milk and milk products. Acquired lactase deficiency is caused by = loss of lactase gene expression early in childhood which type of lactase deficiency is the most common? acquired lactase deficiency acquired deficiency typically manifest after = age of weaning from breast milk transient lactase deficiency is caused by = small bowel injury 1. infectious transient lactase deficiency may occur due to = 2. inflammatory insults transient lactase deficiency is (reversible/irreversible) = reversible if the cause of the injury remits breakdown starts in __ with __ stomach with pepsin 1. frequency diarrhea is increased = 2. volume three or more liquid or semisolid stools daily for at least 2 to 3 what "qualified" as diarrhea? consecutive days 1. increased stool frequency what are the symptoms of diarrhea? 2. increased stool volume 3. decrease in stool consistency acute diarrhea = < 2 weeks chronic diarrhea = > 4 weeks acute diarrhea usually due to = infectious cause the most common noninfectious causes of diarrhea is = medication side effects 1. infectious the majority of cases of diarrhea are = 2. toxic 3. dietary intake What are luminal secretagogues? produced by bacterial degradation of a variety of substrates A toxin from cholera modifies G proteins and permanently acti- How does the toxin from cholera affect G proteins? vates adenylyl cyclase. What is the result of the toxin from cholera modifying G proteins? It increases intracellular levels of cAMP. What is the consequence of strong activation of the apical Cl- Massive secretion of Cl- ions, water, and Na+ ions channels of crypt cells? How much diarrhea can patients with cholera excrete per day? Up to 20 L What can the excessive diarrhea in cholera lead to? Rapid dehydration and death What is an inexpensive and effective treatment for dehydration? Oral rehydration with glucose-containing solutions Glucose drives the sodium-glucose cotransporter to transport How does glucose aid in the absorption of fluids during oral molecules into enterocytes, along with chloride and water, offset- rehydration therapy? ting fluid efflux caused by bacterial toxins What role does fluid and electrolyte secretion play in mucosal It flushes bacterial products and toxins away from the surface of defense? the epithelium. What substances that stimulate fluid and electrolyte secretion Secretagogues known as? Neurotransmitter secretagogues from the submucosal plexus in- 1. VIP clude = 2. acetylcholine 1. bradykinin 2. serotonin Paracrine secretagogues include = 3. histamine 4. prostaglandins Luminal secretagogues include = 1. bacterial toxins (cholera toxin) They act on submucosal neurons to induce the release of acetyl- How do some products from immune cells stimulate secretion in choline or VIP, which then acts on enterocytes to stimulate secre- the gut? tion. 2 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c What are the mediators involved in the indirect stimulation of Acetylcholine or VIP released by submucosal neurons. secretion in the gut by immune cells? what is pseudomembranous colitis? purulent inflammation in the inner lining of the bowel pseudomembranous colitis aka C. diff c.dif can be visualized on = colonoscopy 1. watery diarrhea (e3 loose stool in 24hrs) patients with c.diff infection present with = 2. lower abdominal pain 3. fever 1. distended abdomen patients with severe c.diff infection present with = 2. hypovolemia laboratory findings of c.diff include = 1. leukocytosis 1. hypoalbuminemia laboratory findings of severe c.diff include = 2. lactic acidosis toxins released by c.diff cause = ribosylation of small GTPases 1. disruption of the epithelial cytoskeleton what are some consequences of the ribosylation of small GTPas- 2. tight junction barrier loss es by toxins released by C. difficile? 3. cytokine release 4. apoptosis 1. stool studies how can you diagnose c.diff? 2. sensitive test initially (NAAT or GDH) 3. toxin EIA 1. toxic megacolon abdominal imaging is done for c.diff to rule out = 2. bowel perforation 3. other conditions requiring surgical intervention 1. ORAL vancomycin C.diff is treated with = 2. ORAL fidaxomicin 3. metronidazole 1. hx of recent antibiotic use (clinda most common) what are some risk factors of c.diff? 2. hospitalization 3. e 65 yo what is the treatment for pts with at least 2 c.diff infection recur- fecal microbiota transplantation rences? 1. intraluminal digestion 2. terminal digestion malabsorption results from = 3. transepithelial transport 4. lymphatic transport of absorbed lipids proteins, carbohydrates, and fats are broken down into forms what is intraluminal digestion? suitable for absorption hydrolysis of carbohydrates and peptides by disaccharidases and what is terminal digestion? peptidases in the brush border of the small intestinal mucosa nutrients, fluid, and electrolytes are transported across and what is transepithelial transport? processed within the small intestinal epithelium 1. celiac sprue celiac disease also known as = 2. gluten-sensitive enteropathy immune-mediated disorder triggered by the ingestion of what is celiac disease? gluten-containing foods such as wheat, rye, or barley in genetically predisposed individuals 3 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c 1. luminal Gluten is digested by = 2. brush-border enzymes 1. amino acids gluten is digested into = 2. peptides (33- amino acid ±- gliadin peptide) 1. gastric 33- amino acid ±- gliadin peptide is resistant to degradation by = 2. pancreatic 3. small intestinal proteases what are the immune mechanisms involved in the tissue respons- 1. innate (CD8+ intraepithelial T cells) es to gliadin? 2. adaptive (CD4+ T cells and B cells) CD8+ intraepithelial T cells activated by = IL-15 CD4+ T cells and B cells sensitization to = gliadin 1. varying degrees of villous atrophy what are the result morphologic alterations of celiac disease? 2. increased numbers of intreaepithelial lymphocytes 3. epithelial proliferation with crypts elongation 1. epithelial cells some gliadin peptides may induce ___ to express ___ 2. IL-15 induce epithelial cells will trigger = activation and proliferation of CD8+ intraephithelial lymphocytes CD8+ intraephithelial lymphocytes express = NKG2D natural killer cell marker and receptor for MIC-A NKG2D = What is the consequence of enterocytes expressing surface They are attacked by NKG2D-expressing intraepithelial lympho- MIC-A in response to stress? cytes. What happens when gliadin peptides pass into the lamina pro- They are deamidated by tissue transglutaminase due to epithelial pria? damage. What do gliadin peptides interact with in celiac disease? HLA-DQ2 or HLA-DQ8 on antigen-presenting cells What do CD4+ T cells produce in response to gliadin peptides in Cytokines that exacerbate tissue damage celiac disease? Which HLA alleles are commonly found in people with celiac HLA-DQ2 or HLA-DQ8 disease? what is the unusual plasma concentration value? LDL-C < 60mg/dL LDL-C < 60mg/dL suggest = inherited condition 4 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c a rare autosomal recessive disease characterized by an inability to assemble triglyceride-rich lipoproteins What is abetalipoproteinemia? What causes abetalipoproteinemia? Mutation in microsomal triglyceride transfer protein (MTP) Required for transfer of lipids to nascent apolipoprotein B polypep- What is the role of MTP in abetalipoproteinemia? tide What happens without MTP in abetalipoproteinemia? Lipids accumulate intracellularly what is the evident of epithelial vacuolization? triglyceride accumulation triglyceride accumulation can be highlighted by = 1. oil red-O, particularly after a fatty meal 1. failure to thrive Abetalipoproteinemia presents in infancy with = 2. diarrhea 3. steatorrhea What is the consequence of the defect in lipoprotein assembly? Plasma is devoid of lipoproteins containing apolipoprotein B Leads to deficiencies of fat-soluble vitamins and lipid membrane How does failure to absorb essential fatty acids affect the body? defects, recognized by the presence of acanthocytes in blood smears 1. extremely low level of plasma of cholesterol and TG what would you see in the lab work of abetalipoproteinemia? 2. undetectable in plasma: chylomicrons, VLDLs, LDLs, and apoB 1. progressive pigmented retinopathy 2. decreased night and color vision pts with abetalipoproteinemia may develop = 3. reductions in daytime visual acuity 4. progressing to near-blindness Presence of acanthocytic red cells (spur cells) due to altered lipid content in red cell membranes What is a characteristic finding in peripheral blood smears of individuals with abetalipoproteinemia? 1. acanthocytes What are the two types of spiculated red cells? 2. echinocytes Contracted dense cells with irregular membrane projections of varying length and width Describe acanthocytes. 5 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c Cells with small, uniform, and evenly spaced membrane projec- tions Describe echinocytes. 1. severe liver disease acanthocytes are present in = 2. abetalipoproteinemia 3. McLeod blood group 1. severe uremia echinocytes are present in = 2. glycolytic red cell enzyme defects 3. microangiopathic hemolytic anemia What are the pathologic patterns of motility associated with par- 1. spasms alytic ileus? 2. ileus very strong and often painful contractions that occur continuously what is spams? in a dysregulated manner contractile activity is markedly decreased or absent what is ileus? ileus often results from = irritation of the peritoneum 1. surgery ileus may occur with = 2. peritonitis 3. pancreatitis 1. functional paralytic ileus also known as = 2. pseudo-obstruction failure of normal intestinal motility what is paralytic ileus? 1. intestinal or abdominal surgery 2. acute pancreatitis paralytic ileus often occur after = 3. intestinal infection 4. cardiac dysfunction 5. hypokalemia what are the mechanical causes of acute obstruction? 6 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c 1. adhesions 2. hernias 1. intestinal ischemia 2. necrosis What are the consequences of a strangulated obstruction? 3. perforation if left untreated What is a common cause of chronic pseudo-obstruction? Idiopathic origins 1. tumors What conditions are often associated with partial obstructions? 2. inflammatory disorders especially in the large intestine why is small intestine is most often involved with obstruction of the narrow lumen GIT? 1. hernias 2. intestinal adhesions 3. intussusception what account for 80% of mechanical obstructions? 4. volvulus 20% = tumors & infarction Intussusception occurs when a segment of the intestine tele- What is intussusception? scopes into the immediately distal segment due to peristalsis. Once trapped, the invaginated segment is propelled by peristalsis What happens to the invaginated segment in intussusception? and pulls the mesentery along. 1. intestinal obstruction What are the potential complications of untreated intussuscep- 2. compression of mesenteric vessels tion? 3. infarction what is the most common cause of intestinal obstruction in chil- intussusception dren younger than 2yo? 1. viral infection intussusception often associated with = 2. rotavirus vaccines intussusception in older children/adult (uncommon), generally 1. intraluminal mass caused by = 2. tumor Mucosa and submucosa herniate through muscular layer What is diverticular disease? diverticular disease usually at sire of = arterial insertion 1. chronic constipation diverticular disease predisposed by = 2. connective tissue disease arterial bleeding due to anatomic location What is diverticular bleeding? Irritation or obstruction of diverticular entrance leads to closure What is diverticulitis? and infection 7 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c What complications can diverticulitis cause? Perforation, abscess, fistula with surrounding structures Low fiber diet ’ chronic constipation ’ increased intraluminal pres- sure ’ connective tissue disorders (Marfan syndrome, Ehlers-syn- drome) ’ muscular hypertrophy ’ herniation of mucosa through the muscular wall What is the pathophysiology of diverticular disease? chronic inflammatory condition triggered by the host immune re- What is Inflammatory bowel disease (IBD)? sponse to intestinal microbes in genetically predisposed individu- als What are the two entities encompassed by IBD? Crohn disease and ulcerative colitis Ulcerative colitis is limited to the colon and rectum, involving only the mucosa and submucosa, while Crohn disease can involve any area of the gastrointestinal tract and often produces transmural inflammation. How is ulcerative colitis different from Crohn disease? ulcerative colitis shared risk factors and pathogenesis with __ Crohn Disease Which layers of the colon does ulcerative colitis affect? Affects only mucosa and submucosa of colon How does ulcerative colitis spread in the colon? Contiguous spread from rectum proximally What is the potential extent of involvement of ulcerative colitis in May affect up to terminal ileum the colon? What is the increased risk associated with ulcerative colitis? High risk for colon cancer Name two conditions associated with ulcerative colitis. Associated with PSC and Pyoderma Gangrenosum What is the proposed initial trigger in IBD? Presentation of microbial antigens to CD4+ helper T cells What cytokines induce the differentiation of Th1 and Th17 cells in IL-12 and IL-23 IBD? They activate macrophages, recruit neutrophils, and release What happens after Th1 and Th17 cells are activated in IBD? proinflammatory cytokines like TNF What may cause the presence of microbial antigens in the lamina Defects in epithelial barrier function exacerbated by inflammation propria? What determines whether the disease manifests as ulcerative Differences in the induced cytokine milieu in response to microbial colitis or Crohn's disease? products What are the possible symptoms of Irritable Bowel Syndrome? Diarrhea, constipation, or alternation of both 8 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c What is the main characteristic of IBS? Idiopathic dysregulation of motility Likely multiple phenotypes and mechanisms Altered microbiota, enteric nervous system hypersensitivity to stress Common onset after GI infections What are some common factors associated with IBS? The pancreas is a transversely oriented retroperitoneal organ extending from the C loop of the duodenum to the hilum of the spleen. Where is the pancreas located? Adjacent vessels and ligaments demarcate the pancreas into a head, body, and tail. How is the pancreas anatomically divided? The islets of Langerhans (endocrine portion) and the exocrine portion What are the two main components of the pancreas? 9 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c They serve critical endocrine functions What is the function of the islets of Langerhans in the pancreas? It is a major source of enzymes essential for digestion What is the function of the exocrine portion of the pancreas? What is the significance of diseases affecting the pancreas? They can be a source of significant morbidity and mortality. Due to the retroperitoneal location of the pancreas and the gen- Why do many pancreatic diseases go undiagnosed for extended erally nonspecific signs and symptoms associated with disorders periods of time? of the exocrine portion. Just proximal to the papilla of Vater Where does the main pancreatic duct join the common bile duct? The duct of Santorini What is the name of the accessory pancreatic duct? Through a separate minor papilla How does the accessory pancreatic duct drain into the duode- num? Pancreatic divisum is caused by a failure of fusion of the fetal duct systems of the dorsal and ventral pancreatic primordia. 10 / 11  Disorders of the small intestine and colon Study online at https://quizlet.com/_f6sv1c What is pancreatic divisum? As a result of pancreatic divisum, the bulk of the pancreas (formed by the dorsal pancreatic primordium) drains into the duodenum through the small-caliber minor papilla. How does pancreatic divisum affect drainage? Full-blown acute pancreatitis is a __ medical emergency of the first order Elevation of serum lipase and amylase What are the laboratory findings associated with acute pancreati- tis? increase 4 to 12 hours after onset of pain Which marker is more specific and sensitive for acute pancreati- Serum lipase tis? How long do lipase levels remain elevated in acute pancreatitis? 8 to 14 days reversible inflammatory disorder that varies in severity, from focal What is acute pancreatitis? edema and fat necrosis to widespread hemorrhagic necrosis autodigestion of the pancreas by intraacinar activation of pancre- atic enzymes What causes acute pancreatitis? What accounts for close to 80% of acute pancreatitis cases? Gallstones and chronic excessive alcohol 11 / 11