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Flashcards in GI Deck (144):
1

foregut

pharynx to duodenum

2

midgut

duodenum to proximal 2/3 of transverse colon

3

hindgut

distal 1/3 of transverse colon to anal canal above pectinate line

4

rostral fold closure fail ->

sternal defects

5

lateral fold closure fail ->

omphalocele, gastroschisis

6

caudal fold closure fail ->

bladder exstrophy

7

midgut development

6th week: midgut herniates through umbilical ring. 10th week: returns to abdominal cavity + rotates around SMA

8

pancreatic embryology

derived from foregut. ventral pancreatic buds contribute to uncinate process and main pancreatic duct. dorsal pancreatic bud becomes body, tail, isthmus, and accessory duct. both buds contribute to pancreatic head.

9

annular pancreas

ventral pancreatic bud abnormally encircles 2nd part of duodenum

10

pancreas divisum

ventral and dorsal parts fail to fuse at 8 wks. common. usually w/o Sx, but can -> chronic abd. pain and/or pancreatitis.

11

spleen embryology

arises in mesentery of stomach (= mesodermal). supplied by foregut (celiac) artery

12

where's the portal triad?

in the hepatoduodenal ligament

13

falciform ligament

connects liver to ant. abd. wall. containes ligamentum teres hepatis (from fetal umbilical vein). derived from ventral mesentery

14

hepatoduodenal ligament

connects liver to duodenum. contains portal triad. pringle maneuver: compress by pinching, hold in omental foramen to control bleeding (hole between greater + lesser sacs)

15

gastrohepatic ligament

connects liver to lesser curvature. contains gastric arteries. separates greater and lesser sacs on the right. cut during surgery to access lesser sac.

16

gastrocolic ligament

connects greater curvature w/transverse colon. contains castroepiploic arteries. part of greater omentum.

17

gastrosplenic ligament

connects greater curvature and spleen. contains short gastrics, L gastroepiploic vessels. separates greater + lesser sacs on the left.

18

splenorenal ligament

connects spleen to posterior abd. wall. contains splenic artery and vein, tail of pancreas

19

level of celiac

T12/L1

20

level of SMA

L1 (same as L renal)

21

level of IMA

L3

22

level of aorta bifircation

L4 (bifourcation)

23

SMA syndrome

occurs when 3rd part of duodenum (transverse) is entrapped between SMA and aorta -> intestinal obstruction

24

portosystemic anastamosis: esophagus

L gastric esophageal

25

portosystemic anastamosis: umbilicus

paraumbilical small epigastric veins of ant. abd. wall

26

portosystemic anastamosis: rectum

superior rectal middle and inferior rectal

27

above pectinate line

internal hemorrhoids (not painful cause they have visceral innervation), adenocarcinoma. supplied by superior rectal artery (from IMA). drained by superior rectal vein -> inf. mesenteric vein -> portal system. lymph drainage -> internal iliac nodes

28

below pectinate line

external hemorrhoids (somatic innervation from inf. rectal from pudendal -> painful). supplied by inf. rectal artery (from internal pudendal. drained by inf. rectal vein -> internal pudendal -> internal iliac -> common iliac -> IVC. lymph -> superficial inguinal nodes.

29

anal fissure

tear in anal mucosa below Pectinate line. Pain while Popping; blood on toilet Paper. located Posterior since this area = Poorly Perfused

30

hepatocyte surface orientation

apical faces bile canaliculi. basolateral faces sinusoids.

31

liver zone I

periportal zone: affected 1st by viral hepatitis and ingested toxins (e.g. cocaine).

32

liver zone II

intermediate zone: yellow fever

33

liver zone III

pericentral vein (centrilobular) zone: affected 1st by ischemia. contains cytochrome P-450 system. most sensitive to metabolic toxins. site of EtOH hepatitis.

34

femoral sheath

fascial tube 3-4cm below inguinal ligament. contains femoral vein, artery, and canal (deep inguinal nodes) but not femoral nerve.

35

indirect inguinal hernia

goes through internal (deep) inguinal ring, external (superficial) inguinal ring, and into the scrotum. enters internal inguinal ring lateral to inferior epigastrics. occurs in infants 2/2 processus vaginalis failing to close -> hydrocele. covered by all 3 layers of fascia.

36

direct inguinal hernia

protrudes through inguinal (hesselbach) triangle. bulges directly through abd wall medial to inf. epigastrics. goes through external (superficial) inguinal ring only. covered by external spermatic fascia. older men. MDs don't LIe: Medial to inf. epigastric arte

37

indirect vs. direct mnemonic

MDs don't LIe: Medial to inf. epigastric artery = Direct. Lateral to inf. epigastric artery = Indirect

38

femoral hernia

protrudes below inguinal ligament through femoral canal below and lateral to pubic tubercle. leading cause of bowel incarceration.

39

hesselbach triangle

superolateral: inf. epigastrics
inferolateral: inguinal ligament
medial: lateral border of rectus abdominis

40

gastrin

made by G cells in stomach antrum and duodenum. action: inc. gastric acid, inc. growth of gastric mucosa, inc. gastric motility. reg: +: stomach distention/alkalinization, AAs, peptides, vagal stim. -: pH <1.5. inc. w/H. pylori and chronic PPI use.

41

somatostatin

made by D cells in pancreatic islets and GI mucosa. action: dec. gastric acid, pepsinogen, pancreatic and small intestine fluid secretion, gallbladder contraction, insulin and glucagon release. reg: +: acid. -: vagal stimulation

42

CCK

made by I cells in duodenum, jejunum. actions: inc. pancreatic secretion, gallbladder contraction, sphincter of Oddi relaxation. dec. gastric emptying. reg: +: FAs, AAs. acts on neural muscarinic pathways to cause pancreatic secretion.

43

secretin

made by S cells in duodenum. actions: inc. pancreatic bicarb secretion, bile secretion. dec. gastric acid secretion. reg: +: acid, FAs in duodenum lumen. inc. bicarb neutralizes gastric acid, allowing pancreatic enzymes to fxn.

44

GIP

made by K cells in duodenum, jejunum. action: exocrine: dec. gastric H secretion. endocrine: inc. insulin release. reg: +: FAs, AAs, oral glucose. the reason why oral glucose -> more insulin than IV glucose

45

motilin

made in small intestine. actions: produces migrating motor complexes (MMCs). reg: +: fasting state. receptor agonists (e.g. erythromycin) used to stimulate intestinal peristalsis

46

VIP

made by parasympathetic ganglia in sphincters, gallbladder, small intestine. actions: inc. intestinal water and electrolyte secretion, inc. relaxation of intestinal smooth muscle and sphincters. reg: +: distention, vagal stim. -: adrenergic input.

47

NO

actions: inc. smooth muscle relaxation, including LES. loss of NO secretion implicated in inc. LES tone of achalasia

48

intrinsic factor

made by parietal cells in stomach. actions: vit B12 binding protein

49

pepsin

made by chief cells in stomach. action: protein digestion. reg: +: vagal stim, local acid. pepsinogen -> pepsin in presence of acid

50

SGLT1

Na/glucose or galactose cotransporters

51

GLUT-2

transports all monosaccharides to blood

52

D-xylose absorption test

distinguishes GI mucosal damage from other causes of malabsorption.

53

Fe absorption

as Fe2+ in duodenum

54

bile fxns

digestion and absorption of lipids and ADEK
cholesterol excretion (only way!)
antimicrobial activity (via membrane disruption)

55

esophagitis appearance

candida: white pseudomembranes
HSV-1: punched-out ulcers
CMV: linear ulcers

56

plummer-vinson

triad: dysphagia, Fe-def. anemia, esophageal webs. may be associated w/glossitis. inc. risk of squamous cell CA.

57

curling ulcer

happens w/burns. dec. plasma volume -> sloughing of gastric mucosa (can't sweep away excess acid). "burned by a curling iron"

58

cushing ulcer

happens w/brain injury. inc. ICP -> inc. vagal stimulation -> inc. ACh -> inc. acid production. "always cushion the brain"

59

type A chronic gastritis

in fundus/body. Autoimmune d/o characterized by AutoAbs (side effect, not cause) to parietal cells (-> atrophy), pernicious Anemia, and Achlorhydria (-> G cell hyperplasia). T-cell mediated: type IV HSR. predisposes to adenoCA by -> intestinal metaplasia

60

type B chronic gastritis

antrum. most common type. caused by H pylori Bacteria. inc. risk of MALT lymphoma.

61

menetrier dz

gastric hyperplasia of mucosa -> hypertrophied rugae, excess mucus production w/resultant protein loss and parietal cell atrophy w/dec. acid production. precancerous. rugae of stomach are so hypertrophied that they look like brain gyri.

62

intestinal gastric adenoCA

associated w/H pylori, dietary nitrosamines, tobacco, achlorhydria, chronic gastritis. commonly on lesser curvature. looks like ulcer w/heaped up margins. blood type A association. sister mary joseph nodule = subQ periumbilical met.

63

diffuse gastric adenoCA

not associated w/H pylori. signet ring cells (= mucin-filled cells w/peripheral nuclei). stomach wall grossly thickened + leathery (linitis plastica <- inflammation). krukenberg tumor: b/l ovarian mets produce lots of mucin.

64

ulcer hemorrhage

lesser stomach curvature -> L gastric bleed
posterior duodenum -> gastroduodenal bleed

65

tropical sprue

similar to celiacs but responds to Abx. j + i > d (unlike celiac)

66

whipple dz

infxn w/tropheryma whipplea (GP), PAS+, foamy macrophages in intestinal lamina propria, mesenteric nodes. foamy whipped cream in a CAN: Cardiac Sx, Arthralgias, Neuro Sx. older men. macrophages can accumulate, compress lacteals -> steatorrhea, fat malabsorption.

67

crohns morphology

noncaseating granulomas and lymphoid aggregates (Th1 mediated)

68

UC morphology

crypt abscesses and ulcers, bleeding, no granulomas (Th2 mediated)

69

extraintestinal manifestations: crohns

strictures (string sign), fistulas (can -> UTIs), perianal dz, AK, pyoderma gangrenosum, aphthous ulcers, uveitis, Ca oxalate stones (inc. absorption w/inflam)

70

extraintestinal manifestations: UC

pyoderma gangrenosum, erythema nodosum, PSC, AK, aphthous ulcers, uveitis. p-ANCA.

71

crohns Tx

steroids, AZA, Abx (e.g. cipro, flagyl), infliximab, adalimumab. quit smoking

72

UC Tx

5-aminosalicylic preps (e.g. mesalaine), 6-mercaptopurine, infliximab, colectomy. smoking helps.

73

zenker diverticulum

false. herniation of mucosal tissue at killina traingle between thyropharyngeal and cricopharyngeal parts of inf. pharyngeal constrictor.

74

mutation associated w/hirschsprung dz

RET

75

angiodysplasia

acquired malformation of mucosal and submucosal capillaries from inc. tension. tortuous dilation of vessels -> hematochezia. usually cecum, can be terminal ileum, ascending colon. old people. confirmed by angiography.

76

ischemic colitis

atherosclerosis of SMA. pain after eating -> wt. loss. occurs at watershed areas.

77

hyperplastic polyps

non-neoplastic. generally smaller and majority located in rectosigmoid (L-side).

78

hamartomatous polyps

non-neoplastic, solitary. distorted architecture but otherwise normal tissue. associated w/peutz-jegher + juvenile polyposis.

79

adenomatous polyps

neoplastic via chromosomal instability pathway w/mutations in APC and KRAS. tubular histology = less malignant than villous. ASA = protective.

80

serrated polyp

premalignant, via CpG hypermethylation phenotype pathway w/microsatellite instability and BRAF mutations. "saw-tooth" pattern of crypts on Bx. up to 20% of sporadic CRC

81

inc. risk if polyps are:

>2cm, sessile (flat), villous histologically

82

FAP

AD APC (tumor suppressor) mutation on chromosome 5q. 2 hit hypothesis. 100% progression to CRC w/o resection. pancolonic, always involves rectum.

83

gardner syndrome

FAP + osseous and soft tissue tumors, congenital hypertrophy of retinal pigment epithelium, impacted/supernumerary teeth.

84

turcot syndrome

FAP + malignant CNS tumor (think turcot = turban)

85

peutz-jeghers

AD. numerous hamartomas throughout GI + hyperpigmented mouth, lips, hands, genitalia. associated w/risk of colorectal, breast, stomach, small bowel, and pancreatic CA

86

juvenile polyposis

AD. children, typically <5yrs old. numerous hamartomatous polyps in colon, stomach, small bowel. inc. risk of CRC. solitary rectal polyp = common: can prolapse + bleed

87

lynch syndrome

previously HNPCC. AD of DNA mismatch repair genes w/subsequent microsatellite instability. 80% -> CRC. proximal colon (R-side) = always involved. associated w/endometrial, ovarian, and skin CA. can be identified w/3-2-1 rule: 3 relatives w/lynch across 2 generations, 1 Dx younger than age 50.

88

CRC location & presentation

rectosigmoid > ascending > descending. ascending: exophytic mass, Fe def. anemia, wt. loss. descending: infiltrating mass, partial obstruction, colicky pain, hematochezia. can p/w strep bovis bacteremia.

89

microsatellite instability pathway

~15%. DNA mismatch repair gene mutations -> sporadic and lynch syndrome. mutations accumulate, but no defined morphologic correlates. R-side more common

90

APC/beta-catenin pathway

chromosomal instability. 85%. normal colon (+ loss of APC gene) -> colon at risk (+ KRAS mutation) -> adenoma (+ loss of p53, DCC) -> CA. L-side more common.

91

stellate cells

produce TGF-beta -> fibrosis (in cirrhosis). lie beneath endothelial cells that line sinusoids

92

ALP

= alk phos. Dx of cholestatic and obstructive hepatobiliary dz, HCC, infiltrative d/os, bone dz.

93

AST, ALT

viral hep (ALT>AST), EtOH hep (AST>ALT)

94

amylase

acute pancreatitis, mumps

95

ceruloplasmin

dec. in wilson dz

96

GGT

= gamma-glutamyl transpeptidase. inc. in various liver and biliary dz but NOT in bone dz. associated w/EtOH.

97

lipase

most specific for acute pancreatitis

98

findings of reye syndrome

mitochondrial abnormalities, fatty liver, hypoglycemia, vomiting, coma. associated w/ASA Tx of flu B, VZV. MoA: ASA metabolites -> beta-oxidation by reversible inhibition of mitochondrial enzymes.

99

alcoholic hepatitis histo

swollen and necrotic hepatocytes w/neutrophilic infiltration. mallory bodies = intracytoplasmic eosinophilic inclusions of damaged keratin filaments.

100

causes of inc. NH3 production and/or absorption

dietary protein, GI bleed, constipation, infection

101

causes of dec. NH3 removal

bypassed hepatic blood flow, renal failure, diuretics

102

lactulose MoA

inc. NH4 generation

103

spread of HCC

hematogenous, often through renal vein (-> budd-chiari)

104

cavernous hemangioma

common, benign liver tumor. age 30-50. Bx: dont! b/c of hemorrhage risk

105

hepatic adenoma

rare, benign tumor, often OCP- or anabolic steroid-related. may regress spontaneously or rupture (-> pain, shock).

106

angiosarcoma

malignant endothelial tumor associated with exposure to arsenic, vinyl chloride

107

budd-chiari syndrome

hepatic vein thrombosis/compression -> centrilobular congestive liver dz (hepatomegaly, varices, pain, -> liver failure). no JVD. associated w/hypercoagulation, PV, postpartum, HCC. can -> nutmeg liver

108

alpha1-antitrypsin def. (in liver)

misfolded protein aggregates in hepatocellular ER -> cirrhosis w/PAS + globules in liver. codominant trait.

109

indirect hyperbili causes

hemolysis (overwhelms conjugation), physiologic (low UGT activity), crigler-najjar (no UGT), gilberts (AR, low UGT)

110

general causes of direct hyperbili

obstruction, biliary tract dz, excretion defect

111

causes of obstructive jaundice

gallstones, cholangiocarcinoma, pancreatic or liver CA, liver fluke

112

bili excretion defects

dubin-johnson (AR, dev. b. canilicular transport protein -> dark liver, no Sx), rotor syndrome (similar w/normal appearing liver)

113

mixed hyperbili

hepatitis, cirrhosis

114

what determines urine urobilinogen levels?

how much conjugated bili gets into the duodenum

115

why is urine dark in obstructive jaundice?

conjugated bili is water soluble

116

why is urine dark in hemolytic jaundice?

it is eventually conjugated, excreted into GI tract, and processed into/excreted as urobilinogen

117

gilberts

mildly dec. UDP-glucuronosyltransferase conjugation and impaired bilirubin uptake. bilirubin inc. w/fasting + stress. very common, not worrisome

118

crigler-najjar

absent UDP-glucuronosyltransferase. type 1 presents early, death in 1st few yrs. jaundice, kernicterus. Tx: plasmapharesis + phototherapy. type 2: less severe, phenobarbital -> inc. liver enzyme synthesis

119

dubin-johnson

conjugated hyperbili due to defective excretion. black liver. benign

120

rotor syndrome

like dubin-johnson but even milder and liver appears normal.

121

wilson dz

Cs! low Ceruloplasmin, Cirrhosis, Corneal deposits, Cu accumulation, CA (HCC). AR, chromosome 13: ATP7B gene (hepatocyte ATP cotransporter excretion of Cu into bile). other Sx: hemolytic anemia, basal ganglia degeneration, asterixis, dementia, dysarthria. Tx: chelation w/penicillamine/trientine, oral zinc

122

hemochromotosis

hemosiderosis: Fe (hemosiderin) deposition stains prussian blue (distinguishes from lipofuschin). triad: micronodular cirrhosis, DM, skin pigmentation = bronze diabetes. -> HF, testicular atrophy, inc. HCC risk. AR (primary) or 2/2 chronic infusion Tx. inc. ferrition, inc. Fe, dec. TIBC -> inc. transferrin saturation. H63D or C282Y mutation on HFE gene. association w/HLA-A3. slower progression in women. Tx: repeat phleb, chelation (has "fer" in names)

123

secondary biliary cirrhosis

extrahepatic obstruction (stones, strictures, pancreatic CA) -> inc. intrahepatic pressure -> injury/fibrosis + bile stasis. may be complicated by ascending cholangitis

124

PBS

autoimmune (middle-aged women) -> lymphocytic infiltration + granulomas -> destruction of intralobular bile ducts (-> obstructive jaundice). anti-mitochondrial Ab (including IgM).

125

PSC

young men w/IBD. concentric "onion skin" bile duct fibrosis -> alternating strictures and dilation w/beading of intra- and extra-hepatic bile ducts on ERCP, MRCP. hypergammaglobulinemia (IgM). p-ANCA. can -> secondary biliary cirrhosis, cholangioCA

126

porcelain gallbladder

calcified 2/2 chronic cholecystitis. Tx: phrophylactic chole (high risk of CA)

127

weird causes of acute pancreatitis

steroids, mumps, autoimmune, hyperCa, drugs (sulfa, MRTIs, protease inhibitors), scorpion sting.

128

complications of acute pancreatitis

DIC, ARDS, diffuse fat necrosis, hypoCa, pseudocyst, hemorrhage, infxn, multiorgan failure

129

migratory thrombophlebitis

redness + TTP. associated w/pancreatic CA = trousseau syndrome.

130

palpable, nontender gallbladder

courvousier sign = associated w/pancreatic CA (w/obstructive jaundice)

131

cimetidine

reversible H2 blocker. potent P450 inhibitor. antiandrogenic effects. crosses BBB (-> confusion, dizziness, h/a) and placenta. dec. renal Cr excretion

132

side effects of PPIs

inc. risk of c. diff, pna. dec. serum Mg w/long term us

133

bismuth, sucralfate

bind to ulcer base (physical protection) and allows HCO3- secretion to reestablish pH gradient in mucus layer.

134

misoprostol

PGE1 analog -> inc. production/secretion of gastric mucus + dec. acid secretion. tox: diarrhea.

135

ocreotide

long-acting somatostatin analog. inhibits actions of splanchnic vasoconstriction hormones. Tx: variceal bleeds, acromegaly, VIPoma, carcinoid tumors. tox: N, cramps, steatorrhea

136

antacid side effect

hypokalemia

137

aluminum hydroxide side effects

aluminimum amount of feces + hypophosphatemia, prox muscle weakness, osteodystrophy, seizures

138

Ca carbonate SE

hyperCa, rebound acid inc. can chelate and dec. effectiveness of other drugs (e.g. tetracycline)

139

Mg hydroxide SE

diarrhea, hyporeflexia, hypotension, cardiac arrest.

140

sulfasalazine

combination of sulfapyridine (Abx) + 5-aminosalicylic acid (anti-inflam). activated by colonic bacteria. Tx: UC, crohns. SE: nalaise, N, sulfonamide tox, reversible oligospermia

141

osmotic laxatives

Mg hydroxide, Mg citrate, polyethylene glycol, lactulose

142

ondansetron

5-HT3 antagonist; dec. vagal stim. powerful, central-acting antiemetic. tox: h/a, constipation, QT prolongation

143

metoclopramide

D2 antagonist. inc. resting tone, contractility, LES tone, motility. does not influence colon transport time. Tx: DM and postsurgery gastroparesis, antiemetic. tox: parkinsonian Sx, TD, reslessness, drowsiness, fatigue, depression, diarrhea. drug-drug w/digoxin and DM meds.

144

orlistat

inhibits gastric and pancreatic lipase -> dec. breakdown and absorption of dietary fat. Tx: wt. loss. tox: steatorrhea, ADEK def.