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130 Cards in this Set
- Front
- Back
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Where is the majority of water reabsorbed?
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Jejunum (3-5 L)
Ileum (2-4 L) Colon (1-2L) |
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How does the bowel get water to move into the blood from the lumen?
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Na/K ATPase pumps 2 K into the cell for 3 Na, causing lumen Na to diffuse down it's electric and chemical gradient
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How does oral rehydration work for cholera?
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The Na/glucose transporter is unaffected by cholera toxin. By giving Na/glucose water, glucose and Na will be transported, bringing H20 in with them in excess of what is lost via cholera.
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What happens to concentrations in the stool of Na, K, Cl and bicarb as gut content travels from duodenum to colon?
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Na is absorbed and drops
K is secreted and rises Cl is absorbed and drops bicarb is secreted and rises |
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What does CFTR do in a health person?
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Cystic Fibrosis Transporter regulator - exports Cl-
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What does cholera toxin do?
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Keeps CFTR activated, and reduces Na/Cl transport in absorptive cells, causing excessive diarrhea
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What type of carbohydrates are digestible by humans?
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alpha 1,4 linkages (beta 1,4 and alpha 1,6 indigestible)
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Where are most oligosaccharides digested?
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small intestine on brush border by oligosaccharidases
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What nutrient can inhibit lactase?
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Glucose - which is a product of lactase hydrolysis (self-limiting)
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Where are most carbohydrates absorbed?
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duodenum and proximal jejunum
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Which monosaccharides are actively transported?
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Glucose and galactose
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What is the function of endo vs. exopeptidases?
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Endopeptidases produce polypeptides, Exopeptides produce amino acids and small polypeptides
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Which of the following are exopeptidases? trypsin, carboxypeptidase B, elastase, chymotrypsin, carboxypeptidase A
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carboxypeptidases A/B
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What nutrient do many transporters rely on to import AAs?
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Na
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Where does most protein absorption occur?
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mid-distal jejunum, with some reserve capacity in the ileum
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What disorder results in defective transport of dipolar AAs in the kidney and intestine brush border?
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Hartnup disease. Usually compensated by absorbing polypeptides.
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What disorder results in defective transport of cationic AAs and cysteine at brush border?
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Cysteinuria
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What slows the release of fats from the stomach into the duodenum?
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CCK
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What hydrolizes triglycerides?
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Pancreatic lipase
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What is the role of bile salt?
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Emulsify fats to make it easier for lipases to react with them.
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What is the role of colipase?
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Allows lipase to interact with triglycerides as oil/water interface
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Where is most fat absorbed?
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in the duodenum and proximal jejunum.
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How does Vit D stimulate Ca absorption?
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It's metabolite 1,25 dihydroxycholecalciferol Stimulates it's luminal transporters TRPV5 / 6. Also upregulates it's basolateral transporter PMCA1b.
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Where are iron and calcium absorbed typically?
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In the duodenum
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What does an elevated MMA and normal homocysteine indicate?
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B12 deficiency (homocysteine elevated = folate deficiency)
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What nutritional deficiency might result from long term use of cholestyramine?
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Vit A/D/E/K - fat soluble
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How does osmotic diarrhea present vs. secretory?
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Osmotic diarrhea happens after eating, while secretory persists without eating.
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How do you determine if diarrhea is osmolar?
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Calculate: 2X [Na + K]. If osmolarity is much greater than what you calculate, then unmeasured osmoles are making the difference and causing diarrhea*
If osmolarity is very low, probably was diluted. If osmolarity is very high, probably was treated with concentrated urine or left out standing to ferment. |
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What is osmolarity of secretory diarrhea?
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290 (like serum). Secretory diarrhea is caused by active transport of normal ions into lumen.
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What kind of diarrhea does stimulant laxation cause? Secretory or osmotic?
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Secretory
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What medication for UC relies on gut flora for activation?
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sulfasalazine - to 5-ASA + sulfapyridine
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Where are lithocholic and deoxycholic acid produced?
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In the gut - these are secondary bile acids
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What gut bacteria is associated with obesity?
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firmicutes
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What is associated with more GALT, increased MMC frequency, switch from TH2 to TH1 response
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Gut microbiota
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What type of fiber increases stool bulk?
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Soluble (psyllium)
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What type of fiber increases flatus?
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Insoluble (cellulose)
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What is the substrate for SCFAs produced by gut flora?
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fiber
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What gets protonated and results in bicarb release into lumen?
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SCFAs
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What is a jejunal aspirate used to diagnose?
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bacterial overgrowth in gut
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What is measured in a breath test for bacterial overgrowth?
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Fasting H ions >20ppm, or an increase from baseline of 10-12ppm after lactulose or glucose
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Contrast probiotics with prebiotics
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probiotics are meant to compete with exhisting flora for nutrients, keeping balance (bifidis, lactobacilli, saccharomyces, VSL#3)
Prebiotics are fiber (SC carbs) that should allow for targeted changes in microflora (i.e. bran, sorbitol) |
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What diseases have probiotics been show to improve?
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VSL#3: Pouchitis in IBD post colectomy
Bifidobacter infantis: IBS-D Saccharomyces boulardii: C Diff |
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What are synbiotics?
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Pro + Prebiotic (i.e. bifidis + bran) to help probiotic flourish
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What are postbiotics?
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Bacterial components
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What is the most common bacterium in the GI tract?
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bacterioides (50-60%)
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What are the common bacteria in upper GI?
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Gram pos: staph, strep
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What drug does eubacterium lentum inactivate?
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digoxin
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What might you expect in a person with scleroderma or diabetes with a lot of eructation?
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Small Intestine Bacterial Overgrowth (SIBO)
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Where are trefoil peptides and produced?
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Goblet cells of GI tract
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Where are beta defensins produced?
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Paneth cells of small intestine crypts
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What kinds of cells are destroyed by NK cells?
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Infected or distressed, via INF-gamma
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What are the 4 subtypes of GALT?
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lymphoid tissue (i.e. Peyer's)
lamina propria intraepithelial lymphocytes mesenteric lymph nodes |
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Where are Peyer's patches found?
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Small intestine, covered by a specialized M cell which samples gut content, span the lamina propria to submucosa
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What immune cells are in lamina propria that are NOT found in other GALT?
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eosinophils, mast cells
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Why can't lamina propria T cells leave the lamina propria?
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Restricted by alpha4beta7 integrin, which attaches to MadCAM-1 in mucosa
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What Ig type do most B cells in GALT secrete?
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IgA
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What do mast cells degranulate to produce?
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mostly histamine
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What kind of T helper cells have been discovered to play an important role in IBD?
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Th17, which secrete IL 17
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What component of GALT is increased in Celiac, GvH disease and IBD?
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intraepithelial lymphocytes
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Describe the path of an antigen caught by an M cell in the gut.
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M cell samples Ag, presents to dendritic cell. DC imports to Peyer's patch, which triggers a T cell migration to mesenteric lymph nodes. MLNs produce more lymphocytes which travel to the lamina propria. In LP, plasma cells produce IgA, which is released as secretory IgA via the poly-Ig receptor.
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What are the cytokines from Tregs associated with GI antigen tolerance?
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CD4+CD25+FOXP3 Tregs express CTLA-4 and IL-2 receptors, and produce IL-10 and TNFbeta which diminish immune response
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What are the two serum markers used to identify Celiac?
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tissue transglutaminase IgA (sensitive)
anti-endomysial antibody (specific) |
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What areas does UC typically affect?
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Superficial lesions beginning at rectum, extending to entire colon
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What areas does Crohn's typically affect?
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Can be anywhere in GI tract, granulomatous transmural lesions, occuring in patches at first
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What 2 entities in the IBD spectrum present with non-bloody diarrhea?
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Collagenous and lymphocytic colitis
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What is the significance of CARD15 in IBD?
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First gene identified with association with Crohn's
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What effect does smoking have on UC vs. CD in IBD?
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protective for UC
worsens CD |
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Which IBD has a stronger genetic concordance, UC or CD?
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CD - up to 40% in monozygotic twins
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Why effect does CARD15 have in CD?
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It's an apoptic signaller. Ag binds to leucine rich region in the gene, and signals for cell destruction through NFkB. A mutation causes this to turn off.
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Variants of what interleukin and its receptor are strongly associated with risk/protection from IBD
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IL-23
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What role does innate immunity play in hypothesized pathogenesis of IBD?
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Faulty innate immunity leads to an overzealous adaptive immune response
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What symptom is likeliest to be differentiating for UC vs. CD?
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Rectal bleeding
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What is the first line treatment for UC and CD?
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5-ASA (mesalamine)
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What IBD is ASA most effective in?
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UC, as an enema
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How are steroids helpful in IBD?
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Inhibit IL-2 transcription, stimulate production of IkBa, which traps NFkB in cytosol, preventing apoptosis
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What is the major use of steroids in IBD?
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flare treatment, not maintenance of remission
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Which steroid is likeliest to maintain a remission with fewer side effects for IBD?
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Budesonide
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Which therapy also used in chemotherapy is helpful for steroid-refractory IBD?
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azathioprine (6-MP)
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What drug that inhibits dihydrofolate reductase is a second line option for 6-MP refractory, steroid refractory IBD?
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Methotrexate
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What drug can be administered IV to severe IBD patients refractory to 6-MP?
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Cyclosporine - Anti T Cell also useful for organ transplant
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What are the side effects of Cyclosporine that must be monitored with IV admin?
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Hypertension, kidney damage, paresthesias
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What mab treatments are effective in IBD?
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Infliximab, adalimumab, Certolizumab - anti TNFalphas
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What are the risks of anti-TNFalpha therapy?
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Reactivation of TB, HepB, fungal infection
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What mab attaches to alpha-4 integrin, preventing T cell migration into the gut for CD?
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Natalizumab
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What should be tested via immunoassay prior to administering Natalizumab?
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JC virus - reactivation causes PML
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Where is CARD15 normally constituently expressed?
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Paneth cells of small intestine crypts
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In a male with UC and elevating LFTs, what should you suspect?
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Sclerosing cholangitis
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What important complication of IBD can be exacerbated by steroid use?
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Osteoporosis
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Where is the best developed Meissner's (submucosal) plexus found?
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Small intestine
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How is IBS defined?
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Abdominal discomfort 3+ days per month over 3+ months, associated with at least 2 of:
Improvement with defecation Change in frequency of stool Change in form of stool |
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What is the hypersensitivity of IBS?
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Increased AWARENESS of normal intestinal movements
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What peptides may be altered after resolution of inflammation to cause IBS?
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Substance P increase, causes TNFa release by mast cells
endorphin (or receptor) decrease 5-HT response increase TRPV-1 family increase |
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What peptides are altered with stress that may exacerbate IBS sx?
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CRH can alter gut permeability and bacterial adherence
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Which 5-HT receptor is related to hyperalgesia?
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5-HT3
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What is the major form of energy in TPN?
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Dextrose - 60-70% of non-protein calories
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What might hypercapnia indicate in a patient receiving TPN?
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overfeeding
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What are the approximate caloric needs for TPN?
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25-30kCal/kg. Up for critically ill patients
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How much protein should patients receive per day?
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1g/kg/day
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BV is a 56 year old female who presents with abdominal pain, nausea, and vomiting. She has problems with poor appetite, early satiety, and frequent nausea and vomiting following meals over the past month. During that time, she has lost 18 lbs. Her medical history includes Inflammatory Bowel Disease for 10 years and small bowel resections resulting in an ileostomy. On physical exam she is an ill-appearing female who weighs 150 lbs and 5'5" tall.
Abdominal CT findings demonstrate a bowel obstruction with a fluid collection consistent with an intra-abdominal abscess. She is taken to the operating room where she is found to have a complete bowel obstruction, multiple adhesions, recurrence of Crohn's disease, and a large suprapubic abscess resulting in lysis of adhesions, small bowel resection, and drainage of the abdominal abscess. Residual small bowel is measured at 190 cm. On post-operative day one she has a nasogastric tube than drains 1500 ml/day. Her abdomen is firm, distended, and tender in all four quadrants. No bowel sounds are present. 1. Evaluate BV's weight loss a. Not significant; she has lost 18 lbs but she was overweight to begin. b. On the basis of her BMI of 25, she would not be considered "at nutritional risk" c. Mild weight loss; her current weight is 9% of her usual weight. d. Severe weight loss; she has lost nearly 11% of body weight in one month. |
d. Severe weight loss; she has lost nearly 11% of body weight in one month.
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BV is a 56 year old female who presents with abdominal pain, nausea, and vomiting. She has problems with poor appetite, early satiety, and frequent nausea and vomiting following meals over the past month. During that time, she has lost 18 lbs. Her medical history includes Inflammatory Bowel Disease for 10 years and small bowel resections resulting in an ileostomy. On physical exam she is an ill-appearing female who weighs 150 lbs and 5'5" tall.
Abdominal CT findings demonstrate a bowel obstruction with a fluid collection consistent with an intra-abdominal abscess. She is taken to the operating room where she is found to have a complete bowel obstruction, multiple adhesions, recurrence of Crohn's disease, and a large suprapubic abscess resulting in lysis of adhesions, small bowel resection, and drainage of the abdominal abscess. Residual small bowel is measured at 190 cm. On post-operative day one she has a nasogastric tube than drains 1500 ml/day. Her abdomen is firm, distended, and tender in all four quadrants. No bowel sounds are present. 2. What mode of nutritional support is feasible at this time? |
c. Peripheral parenteral nutrition for an anticipated short course of therapy
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BV is a 56 year old female who presents with abdominal pain, nausea, and vomiting. She has problems with poor appetite, early satiety, and frequent nausea and vomiting following meals over the past month. During that time, she has lost 18 lbs. Her medical history includes Inflammatory Bowel Disease for 10 years and small bowel resections resulting in an ileostomy. On physical exam she is an ill-appearing female who weighs 150 lbs and 5'5" tall.
Abdominal CT findings demonstrate a bowel obstruction with a fluid collection consistent with an intra-abdominal abscess. She is taken to the operating room where she is found to have a complete bowel obstruction, multiple adhesions, recurrence of Crohn's disease, and a large suprapubic abscess resulting in lysis of adhesions, small bowel resection, and drainage of the abdominal abscess. Residual small bowel is measured at 190 cm. On post-operative day one she has a nasogastric tube than drains 1500 ml/day. Her abdomen is firm, distended, and tender in all four quadrants. No bowel sounds are present. 3. What factors will affect decision making regarding long term nutritional management? |
d. All of the above
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What ratio of Omega-3 (linolenic) to Omega-6 (linoleic) should one aim for?
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Lower, by increasing linolenic (fish oil) or decreasing red meat. Normal for Americans is 1:20
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What is an unintentional effect of a low-fat diet to lower LDL?
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Increase triglycerides, and decrease HDL
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What stimulates the release of CCK and GIP?
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fat digestion
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What factors contribute to colithiasis?
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Supersaturated bile, hypomotility, and cystic mucin secretion
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What are black gallstones indicative of?
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hemolysis - made of calcium bilirubinate
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What are brown stones indicative of?
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Helminthic parasite infection -usually in SE asia
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What are most bile stones made of?
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cholesterol
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What type of bile acids are these:
cholic acid chenodeoxycholic acid |
primary bile acids - conjugated in liver
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What type of bile acids are these:
lithocholic acid deoxycholic acid |
secondary bile acids - conjugated in small intestine
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What is the significance of "porcelain" gallbladder on CT?
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Calcification of gallbladder wall - higher risk for cancer, associated with stones
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What appearance is characteristic of a beaded appearance of cystic and common bile ducts on CT?
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Primary sclerosing cholangitis
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What are the 3 endopeptidases in pancreatic juice?
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trypsin, chemotrypsin, elastase (break into smaller polypeptides
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What exopeptidase breaks polypeptides into constituent AAs?
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carboxypeptidase
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What enzyme stimulates bicarb and water production from the pancreas in response to high fat/protein meals?
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Secretin
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What are the most common causes of pancreatitis?
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Gall stones
Alcohol |
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Of the many causes for pancreatitis, what is the common pathway for damage?
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inappropriate conversion of trypsinogen to trypsin
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What does the trypsin activation of elastase, kallikrein and complement produce in pancreatitis?
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Elastase: destroys blood vessels
Kallkrein: increases vascular permeability through bradykinin Complement: increases leukocyte chemotaxis |
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Which of the following is likely to develop chronic pancreatitis? Alcoholism or repeated biliary pancreatitis?
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Alcoholism
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Why does alcohol damage the pancreas?
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Protein plugs form, increase duct pressure, direct toxicity, enhance duodenal reflux
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What does steatorrhea indicate in chronic pancreatis?
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Insufficiency - burnout
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What part of the pancreas produces water and ions?
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duct cells
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What prevents trypsin from auto-digesting the pancreas?
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PSTI - Pancreatic Secretory Trypsin Inhibitor
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What is an indication for drainage of pancreatic pseudocyst?
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Size >12cm
Pain, infection, rapid enlargement, compression of adjacent structures |
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What is the most common genetic disturbance in hereditary pancreatitis?
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PRSS1 - a cationic trypsinogen gene, which disables self cleavage (inactivation)
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What is a common genetic disturbance in idiopathic chronic pancreatitis?
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CFTR mutations
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What type of pancreatitis are the chemokines IL-8, TGF-b, PDGF associated with?
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Chronic pancreatitis
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Which type of pancreatitis is responsive to steroids?
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Lymphoplasmacytic sclerosis pancreatitis - autoimmune
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What is the most frequent type of pancreas cancer?
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Ductal adenoCA
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Which pancreas cancer is more common in children?
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Pancreatoblastoma
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