Unit 1 Flashcards
Be able to ID the 4 layers of the GI tract and describe why variations in those layers are important along the length of the tract
1) mucosa
- epithelial layer
- loose vascularized CT called lamina propria (contains lymphocytes, plasma cells, and macrophages)
- under is thin smooth muscle called muscularis mucosa
2) submucosa
- dense CT, larger blood vessels, nerve plexi, glands, and lymph nodes
- glands only in esophagus and duodenum (Brunner’s)
3) muscularis externa
- inner circle smooth muscle
- outer longitudinal smooth muscle
- nerve plexi between
- fcn in peristalsis and churning lumen contents
4) serosa/adventitia
- squamous epithelial cells separated from underlying muscular layers by thin CT
Describe how the major components of our food sources (proteins, nucleic acids, complex carbs, and lipids) are digested and absorbed. What components and conditions need to be secreted and met in order to do this?
- enzymes secreted to digest
- proteins –> AAs
- carbs –> monosaccharides
- fats –> fatty acids and monoglycerides
carb digestion
- salivary amylase hydrolyzes alpha1,4 –> disaccharides maltose and alpha limit dextrans
- pancreatic amylase hydrolyzes starch –> oligosaccharides and disaccharides
- oligosaccharide hydryolases at BB produce monosaccharides (glucose, galactose, fructose)
- SGLT1 takes up glucose and galactose (Na-dep)
- GLUT5 takes up fructose (fac diff)
- GLUT2 moves all to blood
What mechanisms are in place to avoid digesting ourselves?
- proteases and amylases are released in pro-enzyme from that need to be activated in the proper environment first
- mucus protects the inner layer of epithelium from acid and enzymes
ID the fundamental aspects of mucosal structures/functions that prevent bacterial infection along the GI tract? Describe the organization and role(s) of MALT in the GI tract
- submucosa has a lot of lymphocytes and plasma cells
- mucus provides protection
- IgA
- defensins and lysozymes from Paneth cells in SI
- endogenous gut flora that is protective
- serous epithelial cells of salivary glands secrete lysozyme and peroxidase
Describe the roles of smooth muscle and the enteric nervous system in gut motility, and the advantage of extrinsic control as well
- smooth muscle acts as a unitary structure since the cells are held together by gap junctions and innervated by autonomic nerves
- some cells can spontaneously depol –> APs w/o innervation –> tone at rest and innervation causes contraction or relaxation
- can sustain contraction for a long time
- enteric nervous system: resides in walls of GI tract
- meissner’s and auerbach’s plexuses
- meissner’s: submucosa, pregang para and postgang symp
- auerbach’s: between muscle layers of GI tract, interneurons, sensory/motor neurons, pregang para, and postgang symp
- exist outside of CNS and can control peristalsis without input
- extrinsic parasympathetic NS promotes digestion and peristalsis
- sympathetic NS on blood vessels and glands slows digestion to get blood to extremities
Delineate the requirements for pH control in different regions of the gut. Why in general do we have a much lower pH in the stomach?
- low pH in stomach: activates pepsinogen –> pepsin
- low pH kills bacteria, denatures proteins
- neutralized in duodenum by pancreatic and duodenal enzymes
Describe some of the effects of key endocrine cells in the GI tract and understand their more general roles in regulation of GI coordination
- G-cells: pylorus of stomach; secrete gastri
- A-cells: secrete glucagon
- EC-cells: secrete 5HT
- D-cells: secrete somatostatin; widely dist, except mid stomach
ID the normal histology of the esophagus and be able to differentiate it from other regions of the GI tract
- non-cornified squamous epithelium
- upper is skeletal muscle
- mid is mix of skeletal and smooth
- lower 1/3 is smooth
- see squamous epithelium, blood vessels, muscularis,
- see change at GEJ
Describe the layers of the stomach, ID unique features of cells in these layers and be able to differentiate them from other regions of the GI tract
- cardia: secretes mucus
- fundus: secretes acid and digestive products
- pyloris: secretes mucus and has endocrine cells that secrete gastrin
- stem cells that renew epithelium
- surface mucus cels release mucus and bicarb
- chief cells secrete pepsinogen
- parietal cells pump H ions; stim by gastrin and histamine; secrete intrinsic factor
- have gastric pits
- parietal cells with fried egg appearance
- chief cells towards bottom
Understand the functional significance of rugae in the stomach and plicae circulares in the small intestine
- longitudinal folds (rugae) and transverse folds (plicae circulares)
- increase surface area a lot
- PC are covered with villi which have microvilli
Be able to describe the layers of the small intestine, difference in the duodenum vs. other regions, and the cell types and specific functions in these layers
- crypts of Lieberkuhn: simple tubular glands
- paneth cells: large eosinophilic granules with densins and lysozymes and phospholipase
- brunner’s glands: secrete bicarb into crypts
- villi and microvilli
Describe and be able to recognize cellular structures of the exocrine pancreas. Define differences you would observe between pancreatic acini and acini of salivary glands. Describe the importance of zymogens and their activation
- zymogens: precursor to enzymes that go to pancreatic duct and help in digestion; precursor form to prevent autodigestion of proteins/lipids on the way to ducts to the duodenum
Be able to ID normal histological features and differences among salivary glands
- serous and mucus secretion
ID the layers of the colon, describe the cell types and their roles in the colon, and be able to differentiate the histology of the colon as compared to other regions of the GI tract
- crypts and adipose tissue
- “rack of test tubes”
Achalasia
- inflam destruction of neurons in myenteric plexus of esophagus
- destroys NO prod inhib neurons –> smooth muscle LES cannot relax after swallowing
- test with esophageal manometry
Scleroderma
- fibrosis and smooth muscle atrophy
- lower 2/3 of esophagus and LES –> difficulty swallowing and GERD
- esophageal manometry shows no esophageal body peristalsis
- weakened LES as opposed to hyperactive LES in achalasia
Spastic disorders of the esophagus
- impairment of inhibitory innervation
- chest pain and difficulty swallowing
- inc vigor or rapid esophageal peristalsis while swallowing
Gastroparesis
- delayed gastric emptying w/o obstruction
- feeling full, bloating, nausea, anorexia, vomiting, abd pain, weight loss
- caused by DM, meds, gastric surgery, post-viral, injury to vagus nerve
- test with gastric emptying or wireless motility capsule
What is the MMC?
- migrating motor complex
- sweeps GI tract from stomach to bowel
- 3 phases
- requires intact enteric NS
Intestinal pseudo-obstruction
- obstruction in small or large bowel w/o actual obstruction
- see dilation of bowel on imaging
- caused by degen neuropathies (parkinson’s, DM), chagas, paraneoplastic AI neuropathy
- also by scleroderma, amyloidosis, eosinophilic gastroenteritis
- see abd pain, bloating, distention
- can test with wireless motility capsule or manometry
- treat with antibiotics, nutrition, and prokinetic meds
Constipation
- caused by meds, mechanical obstruction, metabolic disorders, pregnancy, immobility, functional disorders like IBS
- myopathic causes: scleroderma, amyloidosis
- neuropathic: parkinson’s spinal cord injury, MS, autonomic neuropathy, Hirschsprung’s
- test with wireless motility capsule or sitz marker study
Hirschsprung’s disease
- congenital absence of myenteric neurons of distal colon (involving internal anal sphincter) –> lack of reflex inhibition of internal anal sphincter
Dyssynergic defecation
- disorder of coordination of pelvic floor muscles
- contraction of pelvic floor and external anal sphincter during defecation
- fix with biofeedback
Describe the 2 major types of motility in the GI tract, their fcn in digestion, and the differences between them
- segmentation
- peristalsis
Explain how the symp and para systems communicate with intestinal smooth muscle
- para: ACh mediates contraction
- symp: prevents digestion; move blood to extremities
Describe the characteristics of the BER of the SI and its relation to smooth muscle contractile activity
- intrinsic/inherent to muscle (myogenic)
- BER is not enough for contraction; need NT (ACh) input
- ## BER inc as you move down tract
List the stimulus that initiates the swallowing sequence and the events that follow. ID the point at which the swallowing sequence switches from voluntary to involuntary
- three stages: voluntary (bolus pushed by tongue to oropharynx), involuntary (glottis covers trachea, UES relax), involuntary (esophageal peristalsis)
Explain the mechanism of esophageal motility and peristalsis, and the role of the upper and lower esophageal sphincters in this process
- muscle goes from skeletal to smooth as you go down esophagus
- bolus distends wall of esophagus –> activates sensory neurons –> release ACh and substance P –> smooth muscle contracts at oral end of bolus –> force bolus down –> trigger relaxation distal to bolus with NO and VAP and ATP
- LES: prevents backflow from stomach to esophagus
Describe the storage, digestion, and motility roles of the stomach
- storage: stores 3-4L
- digestion: forms gastric acid (disinfectant), digest proteins, produces intrinsic factor
- chyme spurts into duodenum with pyloric sphincter as sieve
- carbs leave stomach in a few hours; protein are slower; fat is slowest
List the phases of the MMC
- every 90min; from stomach to ileocecal valve (doesn’t include LI); motilin activated and neural
- sweeps food and material out
phase 1
- quiescence occurs for 50% of the 90min duration
phase 2
- motility inc with irregular contractions
- doesn’t propel luminal content
- 25% of MMC
phase 3
- 5-10min of intense contractions
- stomach to ileocecal valve
- pylorus fully opens
Compare and contrast the colonic motor activity during a “mass movement” with that during haustral shuttling and the consequence of each type of colonic motility
haustration:
- coordinated movements in both directions
- colon muscles contract intermittently to divide LI into functional segments (haustra)
- similar to segementation
mass movement:
- strong peristaltic waves 1-3x/day
- usually after a meal and lasts a while
Describe the sequence of events occurring during defecation, differentiating those that are under voluntary control from those under involuntary control
- filling of rectum –> relaxation of internal anal sphincter via VIP and NO from intrinsic nerves –> external anal sphincter contracts (rectoanal inhibitory reflex)
- defecation occurs with voluntary relaxation of EAS
What happens in emesis?
- centrally regulated by vomiting center in brain
- steps: salivate (bicarb secretion) and nausea, reverse peristalsis, abd muscle contract and UES and LES relax, gastric contents eject
List the functions of secreted gastric acid
- kills bacteria
- begins protein digestion
- activates pepsinogen –> pepsin
- parietal cells also secrete intrinsic factor for vitB12 abs
- H/K ATPase pumps H across luminal surface against large gradient (uses up a ton of energy)
Describe the protective mechanisms in place to limit toxicity of gastric acid, including occasions where these processes might be disrupted
- mucus and bicarb layer (PGs inc mucus production)
- tight junctions b/w epithelial cells prevent acid from infiltrating layers of wall
- rapid cell turnover maintains integrity
Discuss the modulation of gastric acid secretion throughout the day and night
Phases of HCl secretion:
- interdigestive phase: between meals following circadian rhythms (high in evening, low in morning before waking)
- cephalic phase: neural reg
- gastric phase: neural –> endocrine/gastrin and neural reg
- intestinal phase: mostly endocrine reg
In general terms describe how the 3 parietal cell secretagogues include acid secretion
- muscarinic receptors (ACh), histamine receptors, and CCK receptors (gastrin)
- Ca and cAMP –> rearrangement in cell –> secrete acid
Describe the mechanism of gastric acid generation and secretion, including the roles of K, Cl/bicarb, carbonic anhydrase, and H/K ATPase
- H is actively transported across apical membrane with H/K exchanger ATPase
- bicarb is transported into blood across BL membrane in exchange for Cl into cell
- Cl accumulates in cell –> cross apical membrane
- H2O follows HCl from blood to lumen –> pH of blood leaving the stomach is high due to bicarb (alkaline tide)
Describe the role of the stomach, if any, on the gastric digestion of carbs, proteins, and fats
Carbs:
- amylase is major enzyme in saliva and pancreatic secretions
- sucrose and lactose can be digested at surface of enterocyte
- only simple monomeric sugars can be absorbed
- isomaltase (alpha-limit dextrins –> glucose)
- maltase (maltose and maltotriose –> glucose)
- lactase (lactose –> glucose and galactose)
- sucrase (sucrose –> glucose and fructose)
- trehalase (trehalose –> glucose)
Describe the role of the stomach, if any, on the gastric digestion of carbs, proteins, and fats
- acid denatures proteins
Explain where carb digestion occurs, what enzymes are required, and which sugars they target
Carbs:
- amylase is major enzyme in saliva and pancreatic secretions
- sucrose and lactose can be digested at surface of enterocyte
- *only simple monomeric sugars can be absorbed
- starch –> maltose, maltotriose, and alpha-limit dextrins
on surface of enterocyte:
- isomaltase (alpha-limit dextrins –> glucose)
- maltase (maltose and maltotriose –> glucose)
- lactase (lactose –> glucose and galactose)
- sucrase (sucrose –> glucose and fructose)
- trehalase (trehalose –> glucose)
Predict the SI and colonic consequence of a deficiency in the enzyme lactase following the consumption of dairy products
- lack of lactase (BB enzyme) causes gas and diarrhea due to colonic bacterial digestion of lactose –> osmotic and draws water (diarrhea)
Compare and contrast the carbohydrate uptake mechanisms in terms of location, ions involved, and specificity
- Na/K ATPase causes electrochem gradient
- SGLT1: Na and glucose/galactose come in (cotransport fac dif)
- GLUT5: fructose comes across (Na-indep)
- GLUT2: glucose, galactose, and fructose go into bloodstream through BL surface
- SGLT1 is regulated by sugar; if you eat more carbs –> upreg transporters and inc uptake of simple sugars
List the 4 mechanisms of protein uptake
1) Na-dep cotransporters; H2O follows
2) Na-indep transporters
3) specific carriers for di and tri peptides linked to H ions (cotransporter PEPT1)
4) pinocytosis of small peptides by entereocytes in infants
Explain the roles of pancreatic lipase, colipase, and micelles. Discuss how fat soluble vitamins are absorbed and the consequence of fat malabsorption (steatorrhea) on their uptake
- 1ary bile acids made in liver from cholesterol (cholic and chenodeoxycholic acid)
- 2ary bile acids are formed by bacteria in intestines and colon
- bile acids complex with glycine or taurine to make bile salts
- fat is hydrophobic with low SA; lipase binds to colipase binds to bile salt penetrates fat; form micelles to be easily absorbed
- bile is recycled through distal ileum
- lingual and gastric lipase –> pancreatic lipase (triglyc –> FFAs) –> bile salts (fat into micelles; FFAs to enterocytes) –> triglyc –> chylomicrons into lacteal
Describe the composition and formation of chylomicrons, their movement across the enterocyte BL membrane, and the route of entry into the CV system
- triglyc –> bile salts –> abs –> reform triglyc –> chylomicrons –> into thoracic duct/lacteal
Describe the abs of H2O-soluble vitamins, including the role of IF in the abs of vitB12
- fat soluble vitamins (ADEK) abs along SI and in micelles into chylomicrons
- H2O soluble vitamins through diffusion or specific transporters
Explain the physiological significance of the regulation of luminal H2O content and daily fluid balance. Understand the role of the intestinal epithelia in regulating fluid movement along with the pathways of secretion and absorption of major ions in the SI and LI
- in 9L, out 100-200mL
- H2O follows solutes
- SI becomes iso-osmotic wrt blood
- H2O can move between or through cells
- net fluid secretion from cells in crypts
- ## net fluid abs from enterocytes on villi
List the different classes of diarrhea and the mechanisms by which oral rehydration fluids are able to counter the loss of H2O and electrolytes
- osmotic diarrhea: impaired abs capacity (lactase def, ileal resection so not abs bile salts, celiac disease)
- secretory diarrhea: e.g. cholera; inc cAMP –> activate CFTR Cl channel –> Cl into lumen, Na and H2O follow
Cl absorption
- passive in proximal intestines (loose TJs)
- distal ileum/colon: exchanged for bicarb
K absorption
- passive
- paracellular in jejunum (low K in intercellular space)
- transcellular in colon
- K is high in cells
- diarrhea –> loss of K and hypokalemia
Ca and Mg absorption
- inc in one is loss of other (compete for uptake)
- enters enterocyte passively
- store in intracellular Ca stores
- vitamin D is important; synth in skin or abs in intestine; stim uptake of Ca
Fe absorption
- regulated in proximal intestines
- transport across apical membrane as heme or Fe++
- either binds to apoferritin to form ferritin to stay in cell OR binds to transferrin and leaves cell to go into blood
Fe absorption
- regulated in proximal intestines
- transport across apical membrane as heme or Fe++
- either binds to apoferritin to form ferritin to stay in cell OR binds to transferrin and leaves cell to go into blood
Oral rehydration for therapy
- treat diarrhea
- abx for bacteria
- KHCO3 for hypokalemia and metabolic acidosis
- glucose (Na-dep draws in Na and H2O)
List the tumors of the Appendix
- carcinoid: neuroendocrine and most common
- benign: mucinous cystadenoma (rare but can obstruct and rupture appendix); villous adenoma
- malignant: adenocarcinoma, lymphoma
- secondary tumors (mets)
Name 4 types of diarrhea based on stool characteristics and give examples of each
1) watery [gap = 290-2*(stool Na - stool K)]
- osmotic (gap>50): lactose intolerance, sorbitol, fructose, Mg laxatives
- secretory (gap <50): bacteria, neuroendocrine tumors, bile salt, stim laxatives, motility disorders
2) steatorrhea (fat in stool)
- malabsorption: celiac, whipple’s, SIBO, shortened bowel from surgery
- maldigestion: pancreatic insuff, biliary obstruction
3) inflam/exudative (bloody)
- crohn’s
- ischemia
- infection of colon: c diff, e coli, amebiasis, shigella
4) functional
- IBS
Describe the clinical presentation and causes of fat malabsorption
- weight loss, diarrhea, steatorrhea, vitamin def
- pale bulk malodorous stool
- caused by surgery, bacterial overgrowth, meds, pancreatic insuff, liver disease, intestinal inflamm, ischemia, infiltration
- check for fat in stool
Describe the pathogenesis, diagnosis, and treatment of celiac disease
Pathogenesis:
- inflammatory of SI
- autoimmune response to gluten –> loss of villi due to inc intraepithelial lymphocytes and crypt hyperplasia –> malabsorption of carbs, fats, protein, iron, and folate
- diarrhea, weight loss, bloating, abd pain
- can see dermatitis hepetiformis and iron def anemia
Diagnosis:
- intestinal biopsy (see villi flattening, intraepi lymphocytes, crypt hyperplasia)
- anti-tissue transglutaminase (tTg) IgA ABs
Treatment:
- gluten free diet
Describe the pathogenesis, diagnosis, and treatment of small bowel bacterial overgrowth
Pathogenesis:
- bacterial overgrowth due to hypomotility in scleroderma or diabetes, partial obstruction, diverticula, dec gastric acid secretion
- bacteria inactivate bile acids, catabolize disacch in microvilli, and dec effectiveness of enterokinases
- see diarrhea, steatorrhea, and abd pain, flatulence, bloating, weight loss
- def of vit ADEK and B12
- normal to high folate
- vitamin K normal
Diagnosis:
- aspiration of duodenum with culture (not common anymore)
- glucose-hydrogen breath test
Treatment:
- antibiotics empirically (ciprofloxacin)
Compare the clinical features, pathology, and endoscopic findings of UC and Crohn’s
UC:
- lower abd pain
- hematochezia
- mucus in stool
- tenesmus
- urgency
- affects just colon
- diffuse
- inflam in mucosa and SM
- superficial ulcers
- little fibrosis
- no granulomas
- potential for malignancy
- toxic megacolon
Crohn’s:
- mid or lower abd pain
- N/V
- steatorrhea
- fistulas
- affects entire GI tract
- strictures are common
- skip lesions
- transmural inflam
- deep ulcers
- lots of fibrosis
- lots of granulomas
- obstruction
- malabsorption
- malignancy if colon involved
- can recur after colectomy
Both:
- chronic diarrhea
- weight loss
- fatigue
List the common extra intestinal manifestations of IBD
- autoimmune conditions of eye, skin, bile ducts, and joints
- more common in UC than Crohn’s
- uveitis
- pyoderma gangrenosum
- erythema nodosum
- ankylosing spondylitis
- primary sclerosing cholangitis
Differentiate the clinical and pathologic features of ischemic colitis from those of other types of colitis
Ischemic colitis:
- acute hypoxia from vasospasm
- deydration, hypotension, CV insult
- splenic flexure, rectosigmoid junction
- abrupt lower abd pain
- urgency to defecate
- mild diarrhea +/- hematochezia
- see inflam, ulceration on CT or endoscope
- caused by vasculitis, SLE, PAN, HS, substance abuse, estrogens, mesenteric thrombosis
Diagnose a patient presenting with diverticulosis-related complications including lower GI bleeding or diverticulitis
- diagnose with CT or MRI
Chronic abd pain and diarrhea
IBD
Diagnose a patient with colonic obstruction based on the history, physical exam, and xray findings
Causes:
- tumor
- strictures or volvulus
- foreign body
Signs:
- N/V
- abd distention
- constipation or obstipation
Diagnosis:
- plain xray: air in colon, paucity of air in rectum, distended small bowel and colon
- confirm with CT
Treatment:
- admit to hospital
- NG tube
Hematochezia after surgery or MI
Ischemic colitis
Acute dysentery, travel, ill contacts, or antibiotics use
Infectious diarrhea
Chronic, microcytic anemia
Neoplasia or AVMs
NSAIDs
Drug-induced colitis
History of pelvic radiation
Radiation proctitis
History of pelvic radiation
Radiation proctitis
Small bowel bacterial overgrowth
- from hypomotility (diabetes, scleroderma)
- presents with steatorrhea
- diagnose with duodenal aspiration, glucose-hydrogen breath test
- vit ADEK and B12 def
- folate normal/high
- treat with empirical abx (ciprofloxin)
Celiac disease
- gluten (alpha-gliadin peptide) sensitive enteropathy
- inflam of small intestine
- autoimmune
- HLA-DQ2, DQ8
- enteropathy associated T-cell lymphoma and small intestinal adenocarcinoma
- abd pain, diarrhea, weight loss, fatigue
- steatorrhea
- flatulence
- dermatitis herpetiformis
- biopsy small intestine is gold standard
- loss of villi and scalloped duodenal folds on endoscopy
- positive IgA antibodies to tissue transglutaminase
Celiac disease
- gluten (alpha-gliadin peptide) sensitive enteropathy
- inflam of small intestine
- autoimmune
- HLA-DQ2, DQ8
- enteropathy associated T-cell lymphoma and small intestinal adenocarcinoma
- abd pain, diarrhea, weight loss, fatigue
- steatorrhea
- flatulence
- dermatitis herpetiformis
- biopsy small intestine is gold standard
- loss of villi and scalloped duodenal folds on endoscopy
- positive IgA antibodies to tissue transglutaminase
- tissue biopsy shows: villous blunting, intraepithelial lymphocytes, lymphoplasmacytosis of LP (crypt hyperplasia)
- iron deficiency anemia
- AST, ALT elevations
- treat with gluten free diet
Celiac disease
- gluten (alpha-gliadin peptide) sensitive enteropathy
- inflam of small intestine
- autoimmune
- HLA-DQ2, DQ8
- enteropathy associated T-cell lymphoma and small intestinal adenocarcinoma
- abd pain, diarrhea, weight loss, fatigue
- steatorrhea
- flatulence
- dermatitis herpetiformis
- biopsy small intestine is gold standard
- loss of villi and scalloped duodenal folds on endoscopy
- positive IgA antibodies to tissue transglutaminase
- tissue biopsy shows: villous blunting, intraepithelial lymphocytes, lymphoplasmacytosis of LP (crypt hyperplasia)
- iron deficiency anemia
- AST, ALT elevations
- treat with gluten free diet
Tropical sprue
- visiting tropical areas
- bacterial toxins
- macrocytic anemia from B12/folate def
- villous flattening
- give abx and B12/folate
Whipple’s
- caused by T. whippelii
- LP macrophages absorbed organism –> lymphatic obstruction –> malabs diarrhea
- fever, joint pain, diarrhea, abd pain, CNS symptoms
- PAS stain shows macrophages with whipple bacilli
- villi distended by macrophages
- one year of abx
Mesenteric ischemia
- chronic: 2/3 major vessels occluded
- acute: embolues/severe abd pain
- post-prandial stomach pain, weight loss, diarrhea/malabs
- fecal fat
SI tumors
- most are adenocarcinomas
- then carcinoid, sarcoma, lymphoma
- symptoms of obstruction (abd pain, distention, dec stool)
- get a biopsy
Appendicitis
- inflammation of appendix
- periumbilical pain that radiates to RLQ
- fever, inc WBC, sever pain –> perforation
- get an appendectomy
Inflammatory bowel disease
- females in teens/20s and 80s
- UC and Crohn’s
- chronic diarrhea, abd pain, bleeding for >2wks
- extraintestinal symptoms (uveitis, pyoderma gangrenosum, erythema nodosum, 1ary sclerosing cholangitis (UC), ankylosing spondilitis, osteoporosis)
- screen for cancer
Ulcerative colitis
- T helper type 2 mediated
- bloody diarrhea, weight loss, fatigue
- limited to colon, usually rectosigmoid –> surgery can cure
- LLQ pain
- hematochezia or mucus in stool
- tenesmus (incomplete evacuation)
- diffuse; from rectum more proximal
- toxic megacolon
- ulcer = mucosa+SM
- crypt abscess
- pseudopolyps and loss of haustra
- assoc with 1ary sclerosing cholangitis
Crohn’s disease
- T helper type 1 mediated
- non-bloody diarrhea, weight loss, fatigue
- anywhere but usually terminal ileum and right colon
- periumbilical/mid abd pain
- N/V
- fistula
- strictures
- skip lesions
- granulomas and lymphocytes
- transmural ulcerations
- full thickness inflammation
- cobblestone mucosa
- malabsorption
Microscopic colitis
- 50-80yo females
- lymphocytic and collagenous
- assoc with celia, NSAIDs usually a cause
- chronic mild secretory diarrhea non-bloody
- no gross features, just on histology
- lymphocytic infiltration of mucosa
- thickened subepi collagenous band
- treat with antidiarrheals
Ischemic colitis
- usually >60yos
- caused by vasospasms, dehydration, hypotension, MI, PE
- affects splenic flexure and rectosigmoid (wateshed)
- abrupt onset, crampy lower abd pain
- loss of peristaltic sounds
- mild diarrhea +/- hematochezia
- get a colonoscopy and treat triggers
Irritable bowel syndrome
- 20-40yo females
- chronic recurrent abd pain, bloating
- improve with defecation
- get endoscopy and tissue biopsy
Infectious colitis (campylobacter spp)
- from poultry, water, and unpast dairy
- watery diarrhea +/- blood
- friable colonic mucosa
- treat with antibiotics
Infectious colitis (shigella)
- highest infectivity rate
- water contaminated with feces
- severe watery or bloody diarrhea
- hemorrhage, exudates, pseudomembranes
- mimics IBD
- treat with abx
Infectious colitis (salmonella)
- food poisoning or traveler’s diarrhea
- non-typhoid: mild gastroenteritis, diarrhea in 2nd week of infection
- typhoid: pain, HA, fever, rash, leukopenia, perforation, toxic megacolon
- mucosal redness, ulceration, exudates on endoscopy
- treat with abx
Infectious colitis (e. coli)
- enterotoxigenic: secretes toxin; diarrhea
- enterovasive: similar to shigella; travelers’ diarrhea
- enterohemorrhagic: contaminated meat –> renal failure; bloody diarrhea; necrosis and hemorrhage
- ## enteroadherent: non-bloody diarrhea
Infectious colitis (pseudomembranous)
- C diff after course of abx (3rd gen cephalosporins)
- common in hospitalized patients
- fever, leukocytosis, abd pain, cramps, non-bloody watery diarrhea
- pseudomembrane formation; loss of crypts; volcano-like eruption of neutrophils
Infectious colitis (CMV)
- affects anywhere in GI tract
- cytomegaly (large cells)
Infectious colitis (herpes virus)
- usually esophagus and anorectum
- intranuclear inclusion
Infectious colitis (rotavirus)
- most common cause of childhood diarrhea (now have 2 vaccines)
- severe dehydration
Infectious colitis (adenovirus)
- second most common cause of childhood diarrhea
- in AIDS patients
- diarrhea, dehydration
- self resolves
- villous atrophy
Infectious colitis (norovirus)
- half of all gastroenteritis outbreaks
- contaminated foods and person to person
- diarrhea; SI affected
Infectious colitis (protozoan)
Entamoeba histolytica
- dysentery-like fulminant colitis –> goes to liver and cecum
- flask-shaped ulcers in mucosa
Giardia:
- explosive watery diarrhea, abd pain, N/V
- duodenum
- schools of fish on histology
Cryptosporidium parvum:
- usually in IC kids
- diarrhea, weight loss, fever, pain; usually SI
- mild erythema and mucosal granularity on endoscopy
- basophilic ADD
- treat all with anti-parasite therapy
Infectious colitis (helminthes)
Ascaris lumbricoides (roundworm)
- soil infected with feces
- obstruction, perforation, growth retardation
Strongyloides stercoralis (nematode):
- penetrates skin –> lungs –> esophagus –> SI
- diarrhea, pain, rash, pruritis
Schistosomiasis:
- exposure to contaminated water and skin penetration
- bloody diarrhea, anemia, weight loss
Drug-induced colitis
- mimics IBD or ischemia
- NSAIDs usually cause
- pain and diarrhea
- do colonoscopy to confirm and discont drug
Radiation colitis
- radiation proctitis is most common (from pelvic radiation for treating cervical or prostate cancer)
- hematochezia, diarrhea, painless rectal bleeding
- see edema and telangiectasia on colonoscopy
Diverticulosis
- outpouching of colon
- usually in elderly
- due to low fiber diet
- hemorrhage (5%); usually right colon that is painless
- get CT or MRI
- no inflam cells
- treat with high fiber diet
Acute diverticulitis
- fecolith obstructs a diverticulum –> inflammation –> microperforation, abscess, or peritonitis
- usually in sigmoid colon
- acute LLQ pain, nausea, fever
- not usually w/ diarrhea
- can lead to obstruction, perforation, abscess formation, bleeding –> sepsis
- get CT or MRI and see inflam cells
Zenker’s diverticulum
- outpouching of oropharynx from muscle wall defect
- above UES at esophagus and pharynx junction
- dysphagia, obstruction, hal
- treat with surgery
GERD
- reflux of gastric acid into esophagus
- more common in obese patients
- RFs: high fat diet, caffeine or alcohol, tobacco, meds, age
- inappropriate LES relaxation
- hiatal hernias
- ZES, Sjogrens, scleroderma
- heartburn, especially postprandial and lying down
- diagnose with 24hr pH study or just give PPI or antacids and evaluate
- see inc eosinophils in distal esophagus
- progresses to erosive esophagitis then to barret’s esophagus then to adenocarcinoma
Achalasia
- no relaxation of LES
- disorderly peristalsis
- vagal input to LES is impaired or secondary to diabetic neuropathy
- solid and liquid dysphagia
- chest pain, regurg, weight loss, halitosis
- diagnose with esophageal manometry
- see bird’s beak on esophagram
- EGD or CT to rule out cancer
- absence of ganglia in distal esophagus and LES on pathology
- treat with balloon dilation of LES, nitrates, CCBs, or botox injection into LES
Eosinophilic esophagitis
- eosinophilic infiltration
- diffuse narrowing of esophagus
- males usually younger than 50yo
- allergic causes (look for allergic history i.e. asthma, psoriasis, etc.)
- dysphagia +/- food impaction (due to fibrosis and eventual stricture)
- see concentric rings on endoscopy, nodular plaques, exudates
- biopsy shows eosinophils in mid esophagus
- treat with topical steroids
Barrett’s esophagus
- consequence of GERD
- can progress to adenocarcinoma
- RFs: hiatus hernia, white, M>F, smoking, obesity (same as GERD)
- asymptomatic or heartburn
- metaplasia where squamous –> glandular columnar
- salmon colored patch on endoscopy
- alcian blue stain shows acidic mucus/goblet cells
- treat GERD, inc screening, ablation, mucosal resection
Esophageal cancer
- dysphagia, weight loss, sometimes hematemesis, chest pain, anemia
Adenocarcinoma:
- GERD/Barrett’s
- distal esophagus
- resect, chemo, metal stent
SCC:
- RFs: smoking, alcohol, caustic injury, really hot tea, poor oral health
- upper/mid esophagus
- resect, chemo, metal stent
Work up for esophageal disorders
Dysphagia:
- coughing, aspiration –> suspect NM disorder, benign obstruction, neoplasia –> do a barium swallow
Esophageal Motility Dysfunction:
- pain +/- dysphagia –> GERD, achalasia, esophageal spasm –> manometry
Benign Structural Disorder:
- painless +/- solid food dysphagia –> strictures, EoE –> EGD
Neoplasia:
- painless +/- solid food dysphagia + cancer symptoms (weight loss, fatigue, etc.) –> esophageal cancer –> endoscopy and biopsy
Infectious esophagitis
Herpes:
- usually in IC patients
- pain w/ swallowing, dysphagia, GI bleed
- see punched out ulcers on endoscopy
- multinuc cells, intranuclear viral inclusion on histo
- give antiviral
Candida:
- most frequent infection
- in IC patients
- pain with swallowing
- white plaques on endoscopy and exudates
- pseudohyphae and budding yeast on histology
CMV:
- in IC patients
- usually with candida
- pain w/ swallowing
- punched out ulcers in distal esophagus on endoscopy
- cyto and nucleomegaly and intracytoplasmic inclusions on histology
Mallory-Weiss tear
- longitudinal, linear superficial tears
- presents with alcoholics or bulemics
Describe the epidemiology, pathophysiology, and treatment of H pylori infection
- HP produces urease which produces ammonia which raises local pH
- virulence factors avoid destruction by gastric acid, colonize gastric epithelium, damage epithelial cells, cause inflam
- injects CagA which can activate NFkB, dec cell adhesion assoc with gastric and duoenal ulcers
- VacA: makes pores in membrane, inhibits T cells
- can suppress Treg
- epidemiology: age-dep in developed countries; crowded, low SE status; oral transmission
- diagnosis: mucosal biopsies, CLO test; blood antibody; urea breath test; stool antigen test
- treat with PPI, amoxicillin, clarithromycin
ID the causes of gastritis
- infection usually by H pylori, but infectious gastritis in general is uncommon; can be syphilis, TB, candida, giardia, etc.
- ## three types: mild/diffuse chronic and active, antral predominant (high acid secretion –> ulcer), multifocal atrophic gastritis
Describe PUD pathogenesis
- gastroduodenal mucosa defenses are unable to protect epithelium from acid and proteases like pepsin –> disease of failed mucosal integrity, not acid hypersecretion
- RFs: H pylori infection and NSAID use
- may be asymptomatic, present with burning epigastric pain; relieved with food or antacids; pain comes and goes
- complications are: bleeding (inc NSAID use among elderly –> HP infection), perforations (due to acute peritonitis), obstruction (not common; causes N/V)
Explain PUD treatment
- anti-acid secretory meds
- liquid antacids like Maalox
- PPI and H pylori eradication
List the 5 most common types of gastric neoplasms
Adenocarcinoma:
- diffuse (signet ring, inc mucin) or intestinal (gland formation)
Gastric polyps:
- hyperplastic: prolif of mucus producing cells from chronic inflam; seen in AI gastritis and H pylori infection with chronic atrophic gastritis; can lead to dysplasia or adenocarcinoma
- adenoma: from dysplastic epithelial cells –> adenocarcinoma; FAP
- fundic gland: dilated oxyntic glands lined by flattened parietal and mucus cells; most common polyp due to PPI long term
Stromal tumors/GISTs:
- leiomyomas and lipomas
- SM bulging into lumen, subserosal into lumen or both
- usually asymptomatic, but if large –> abd pain and GI bleeiding
- treat with resection
- GISTs have different prognosis and treatment; express c-KIT (CD117) –> treat with imatinib
Neuroendocrine tumors:
- carcinoid arise from enterochromaffin cells
- 2 types of carcinoid tumors: sporadic (may metastasize, but try to resect) and achlorhydria due to atrophic gastritis (high levels of gastrin due to achlorhyria)
Lymphoma:
- strong assoc with H pylori infection and 1ary gastric Bcell lymphoma
- low grade clonal proliferation of Bcells in HP induced gastric MALT
- eradicate HP, but if not may become high grade lymphoma
Eosinophilic gastritis
- infiltration of gastric walls with eosinophils
- mucosal ulceration or luminal obstruction
- gastroparesis
- rule out parasitic infestation
- treat with corticosteroids and surgery
Menetrier diseas
- hypertrophic rugal folds, spares the antrum, foveolar hyperplasia, cystic dilation into SM
- abd pain, weight loss, bleeding
- hypoalbumnemia
Zollinger-Elison syndrome
- gastrin secreting neuroendocrine tumor stimulates parietal cells and increases acid secretion
Zollinger-Elison syndrome
- gastrin secreting neuroendocrine tumor stimulates parietal cells and increases acid secretion
Gastritis
- infection usually by H pylori, but also syphilis, TB, fungal, CMV, candida, etc.
- HP is a gram neg rod
- more common in developing countries in younger ages; older ages in developed countries
- urease converts urea to ammonhia –> inc pH
- abd pain, N/V, blood if ulcer
- may progress to PUD and cancer
- diagnose: endoscopy with mucosal biopsy, urease breath test
- 3 forms: mild/diffuse, antral predom (high acid secretion), multifocal atrophic (low acid, but inc cancer risk)
- treat: triple therapy (PPI, clarithro, amox for 2 weeks), or quad therapy (PPI, metro, tetrac, bismuth)
- other causes: NSAIDs, autoimmune
Gastritis
- infection usually by H pylori, but also syphilis, TB, fungal, CMV, candida, etc.
- HP is a gram neg rod
- more common in developing countries in younger ages; older ages in developed countries
- urease converts urea to ammonia –> inc pH
- abd pain, N/V, blood if ulcer
- may progress to PUD and cancer
- diagnose: endoscopy with mucosal biopsy, urease breath test
- 3 forms: mild/diffuse, antral predom (high acid secretion), multifocal atrophic (low acid, but inc cancer risk)
- treat: triple therapy (PPI, clarithro, amox for 2 weeks), or quad therapy (PPI, metro, tetrac, bismuth)
- other causes: NSAIDs, autoimmune
Peptic Ulcer Disease
- due to failed mucosal integrity not acid hypersecretion
- NSAIDs and HP
- burning epigastric pain
- abd pain, anemia, acute bleeding, perforation, obstruction, subepi hemorrhage
- treat with PPI/H2 blockers and eradicate HP
Peptic Ulcer Disease
- due to failed mucosal integrity not acid hypersecretion
- NSAIDs and HP
- burning epigastric pain
- abd pain, anemia, acute bleeding, perforation, obstruction, subepi hemorrhage
- treat with PPI/H2 blockers and eradicate HP
- treat bleeding with IV fluids, PPI, surgery if necesary
Hyperplastic gastric polyps
- assoc with chronic gastritis
- high gastrin –> inflammation
- AI gastritis is common
- prolif of foveolar epi and LP
Adenoma gastric polyps
- assoc with chronic gastritis
- intestinal metaplasia
- high risk of malignancy
- gastritis –> metaplasia –> adenoma (low grade) –> high grade –> adenocarcinoma
- premalignant; assoc with FAP
Fundic gland polyps
- assoc with chronic PPI and FAP
- cystic dilation of fundic glands
Gastric adenocarcinoma
- assoc with HP, chronic gastritis
- intestinal: RFS are age, male, tobacco, diet, smoked foods, salted fish, FAP; glad forming and assoc with atrophic gastritis
- diffuse: younger, CDH1 mutation, worse prognosis; signet ring and inc mucin and linitis plastica
- see weight loss, abd fullness, anemia
GISTs
- benign gastric tumors from stroma
- cells of Cajal
- weight loss, anemia, dyspepsia
- pain bleeding if large
- submucosa
- positive for c-kit (CD117)
- give gleeva/imatinib or surgery
Carcinoid
- neuroendocrine tumor
- usually SI
- AI gastritis, ZES, sporadic
- gastrinoma, insulinoma, VIPoma,
- prolif of endochromaffin cells of SI
- resect
MALT lymphoma
- low grade B cell lymphoma from HP
- RFs are celiac, IBD, immunodeficiency
- translocation of NFkB
- HP infection –> low grade B cell prolif (BCell MALToma) –> high grade lymphoma
Describe the protective and damaging processes that are commonly deranged in gastric disease
- surface mucosa secretion
- bicarb secretion into mucus
- mucosal blood flow
- epithelium can regenerate
- PGs
^^^these processes are damaged by HP, NSAIDs, etc.
- can also be by ischemia and shock
List the general features and causes of acute and stress-related gastritis
- causes: NSAIDs, EtOH, tobacco, HP, bile, strong acids/bases
- features: erythema, erosions
Acute:
- destruction of mucosa
- lots of inflmmatory infiltrate
Stress:
- resembles acute gastritis
- mediated by ischemia/vasoconst
- erosion and ulceration widespread
- common in critically ill patients
Describe the pathophysiology, epidemiology, and common sequelae of Helicobacter infection
- gram negative bacillus, spiral shaped; flagella
- resists acid through urease
- adhesion binds to gastric foveolar cells
- toxins to cause tissue damage
- oral-oral, fecal-oral environmental spread
- assoc w poverty, crowding, rural areas
- histo shows HP in surface mucosa of cells; see neutrophils and lymphoctes and plasma cells into gastric mucosa
Describe the pathophysiology and common sequelae of AI gastritis
- restricted to body
- chronic
- atrophic
- CD4+ T-cells attack parietal cells
- anti parietal cells and anti IF antibodies –> can be used for diagnosis
- can lead to pernicious anemia
- histo: lympocytes and plasma cells in body of stomach; atrophy of glands; intestinal metaplasia