GI Flashcards
What do rostral and caudal mean?
Rostral: head
Caudal: tail
What does failure of caudal wall lead to?
Bladder exstrophy
What does failure of caudal wall =?
Sternal defects
What does failure of lateral wall =?
Gastroschisis
3 arterial supplies to gut and what do they supply?
Celiac: foregut
SMA: Midgut
IMA: hindgut
What does the foregut become and what supplies it?
- Pharynx -> duodenum
- Liver
- Gallbladder
- Distal stomach
- Pancreas
- Supplied by celiac
Organ supplied by celiac that is not derived from foregut?
Spleen: derived from mesoderm, NOT endoderm
What layer makes most GI tract?
Endoderm
What does the hindgut become?
Distal 1/3 gut -> internal anus
- supplied by IMA
What does the midgut become? What supplies it?
- Jejunum -> proximal 2/3 colon
- Supplied by SMA
How does midgut develop?
Needs more space so from week 6 - 10 develops outside of abdomen
- Must rotate 270 degrees around SMA before can move back in
What is omphalocele?
- Failure of gut to rotate around SMA and reduce into abdomen at week 10
- Left stuck outside body with peritoneal covering
- Associated with trisomies
Difference between gastroschisis and omphalocele?
Gastroschisis does not have peritoneal covering and is adjacent to belly button
Presentation of esophageal atresia with TE fistula?
- Polyhydramnios as fetus cannot swallow
- Vomit / regurg on first feeding
- Drooling choking
- Gastric air bubbles on CXR
What is associated with duodenal atresia?
Down syndrome
What does double bubble sign mean?
Duodenal atresia
- Air is stuck in stomach and again in duodenum below pyloric sphincter
What does triple bubble sign mean?
Jejunal or ileal atresia
- Ligament of treitz is separating air into third bubble
Signs of duodenal atresia?
- Polyhydramnios
2. Bilious emesis (green)
How to tell duodenal from esophageal atresia?
There is not bilious emesis seen in in esophageal as atretic lumen is before bile is secreted in SI
What is sphincter of Oddi?
Where bile enters duodenum from common bile duct
What is hypertrophic pyloric spincter?
- Slow hypertrophy of sphincter AFTER birth
- Presents 1 month AFTER birth in contrast to atresias
1. Palpable olive shaped mass
2. Projectile vomiting
3. Non bilious vomit
What are the retroperitoneal structures?
“SAD PUCKER”
Suprarenal glands
Aorta / IVC
Duodenum 2 - 4th parts
Pancreas - except tail Ureters Colon (ascending and descending) Kidneys Esophagus Rectum
Which ligament does the portal triad travel through? What makes up the triad?
Hepatoduodenal ligament
- Common bile duct
- Hepatic artery
- Portal vein
What is the pringle maneuver?
Getting the liver to stop bleeding by compressing the hepatoduodenal ligament: the hepatic artery is found in here as well as rest of portal triad
First branch of aorta and where does it branch?
Common iliac arteries at L4
Where is IVC relative to aorta?
- To the right
- Anterior to renal / adrenal A
- Posterior to right gonadal A.
Left abdominal venous drainage to IVC?
- Renal vein is only vein that makes it to IVC
- Both gonadal and adrenal vein merge with renal then ride over
What is SMA syndrome?
- Normally, SMA travels in mesentery of fat over curvature of duodenum which give it cushion
- In malnourished folks, mesentery is lost and duodenum compressed between SMA and aorta = obstruction
1. Postprandial pain
2. Nausea / vomiting
Innervation of celiac / SMA area?
Greater and lesser splanchnic nerves T5-T12
Innervation of IMA area?
Lumbar splanchnic nerves L1 - L2
What does celiac arterial branch into?
- Left gastric: lesser curvature of stomach
- Common hepatic
- Splenic
What does left gastric artery do?
- Small branch to esophagus
2. Anastomosis on lesser curvature of stomach
What does splenic artery do?
- Body and tail pancreas
- Spleen
* **Short gastric artery: supplies fundus
What does hepatic artery do?
- Gastroduodenal:
- Proper hepatic: part of portal triad to liver
* *Also branches into Right gastric which anastomoses with left
Main blood supply to liver?
Portal vein: 80% volume, 50% oxygen
Venous blood to liver?
Portal to liver, hepatic veins to IVC
- Splanchnic, IMV, SMV feed liver
What is the ligamentum teres?
Used to be umbilical vein: if pressure in portal vein too high, recanalized and blood flows through it to umbilical area where cutaneous veins head back to VCs
**Caput medusae in portal HTN
Left gastric anastomoses from portal vein?
Left gastric -> esophageal veins -> Azygos vein - > SVC
IMV anastomosis from portal?
Rectal veins -> IVC - > heart
***This is why rectal absorption of drugs is better than liver as it bypasses liver
What does TIPS connect?
Hepatic vein to portal vein to bypass increased pressure
- However, the liver is no longer filtering
What is pectinate line?
Where the endoderm and ectoderm met at the anus
Venous drainage above pectinate line? Lymph? Cell type? Nervous?
- Superior rectal
- IMV
- Portal vein
Lymph: internal iliac
Histo: simple columnar
Nerves: Visceral pelvic splanchnic
Venous drainage below pectinate line? Lymph? Nervous?
Bypasses liver: 1. Middle / inferior rectal veins 2. Internal pudendal 3. Internal iliac 4. IVC Lymph: superficial inguinal Histo: Stratified squamous Nerves Pudendal
Which hemmorhoids are painful?
- External
- Internal = visceral innervation = non specific and dull `
Presentation of anal fissures?
Caused by constipation
- Painful defecation
- Blood on TP
What is central vein?
Found at center of hepatic lobules: drains blood from hepatic a. and portal vein to carry blood to hepatic veins and IVC
What are Kupffer cells? What are the important in?
Macrophages that line hepatic sinusoids
- Break down RBCs to make heme which makes bilirubin
- Hepatocytes accept the bilirubin to conjugate and excrete it
Where are Zone 1/3?
Zone 1: closest to triad, metabolizes and does O2 intensive tasks
Zone 3: Closest to central vein: CYP450 metabolism
Which zone of liver most susceptible to ischemia?
Zone 3, furthest from triad which has higher O2
Which zone most susceptible to toxins?
Zone 1: has not yet hit cyp450 which is in liver
What is toxic to zone III?
Alcohol and tylenol: both need to be metabolized before they become toxic
Which zone susceptible to hepatitis?
Zone 1
What is zone 2 susceptible to?
Yellow fever
Flow of bile from liver?
- Hepatic duct: drains bile from liver to sphincter of oddi to duodenum
- As oddi is usually closed, refluxes up cystic duct into gallbladder
- Common bile duct is distal to cystic and hepatic duct
What is the ampulla of vater?
Where common bile duct and pancreatic ducts meet
What are cholelithialsis?
Gallstones
What is cholecystitis?
Inflammation of gallbladder resulting from cholelithiasis
What is choledocolythiasis? Presentation?
Stone that has migrated down to common bile duct
- Jaundice: bile buildup in body
- Pale stools: bile colors stools
- Liver inflammation
Where would stone need to be to obstruct bile flow completely?
Common bile duct “choledocolithiasis”
- If only obstructing cystic duct, liver can still drain some of content town towards oddi
Where does stone need to be to cause inflammation of both bile duct and pancreas?
Confluence of pancreatic duct and common bile duct “ampulla of vater”
What else can obstruct the bile duct?
Pancreatic cancer
How to tell bile obstruction from stone and cancer?
Cancer usually presents with palpable, PAINLESS gallbladder
What hernia is more common in women?
Femoral
3 layers of inguinal canal?
- Transversalis fascia (NOT muscle)
- Internal oblique
- External oblique
What does the cremaster do?
Moves testis up and down to adjust for temperature
What does remnant of distal process vaginalis cause? Proximal?
Distal: Hydrocele
Proximal: indirect inguinal hernia, comes through deep inguinal ring to inguinal canal
What do direct and indirect hernias pop through?
Indirect: deep inguinal ring
Direct: superficial ring from abdominal wall
Indirect or direct hernal more common in elderly?
Direct as it needs to plow through a week abdominal wall
Which hernia covered by all 3 layers of inguinal canal?
Indirect
Direct: only covered by external spermatic fascia
Landmark for direct and indirect hernias?
Indirect: lateral to inferior epigastric vessels
Direct: Medial to inferior epigastric vessels
What occurs in hesselbach’s triangle?
Direct inguinal hernias
Which hernias are almost all male?
Indirect
What is sliding hiatal hernia?
Stomach pops up through diaphragm
What is paraesophageal hernia?
Fundus of stomach passes through diaphragm to side of esophagus
Presentation of diaphragmatic hernia?
- Asymptomatic
2. Reflux
Risk of congenital diaphragmatic hernia?
- Deadly lung HYPOplasia as lungs have nowhere to go
2. Causes pulmonary HTN and right HF
Where is gastrin produced and what does it do?
G cells of stomach antrum:
- Stimulates ECL to secrete histamine (endocrine)
- Stimulates parietal HCL
- Promotes growth of gastric mucosa
- Increases gastric motility
Regulation of gastrin?
Increased: 1. Stomach distension 2. AAs / peptides in stomach 3. Vagal release of GRP 4. Alkalinization 5. PPIs 6. ZE syndrome 7. Chronic gastritis Decreased: 1. PH
What is Zollinger ellison syndrome?
Gastrinoma
- Pancreatic tumor secreting gastrin
What occurs in chronic gastritis?
Parietal cells are destroyed, G cells keep secreted gastrin as not receiving negative feedback
Where is somatostatin made and what does it do?
D cells of pancreas:
- Stops secretions of pretty much everything
- Decreased gallbladder contraction: increased risk gallstones from stasis
What does somatostatin do in brain?
Released by hypothalamus to reduce GH secretion
What is octreotide? Side effect?
Somatostatin analogue: side effect of gallstones as it stops gallbladder contractions
Stimulation of somatostatin?
Increase:
1. Acid
Decrease:
1. Vagas
What does cck do? Where is it made? What increases?
“Cholecystokinin” ***Think CHOLE = gall bladder
- Made by I cells in SI
1. Increase pancreatic secretions
2. Contract gallbladder
3. Increase pyloric emptying
4. Relax oddi: bile secretion - **Increased by fat in duodenum
Main purpose of bile?
Help emulsify fats from food
Where is secretin made? What does it do?
- Increases secretions
- Made by S cells of duodenum
1. Increased bicarb
2. Increased bile
3. Decreased gastric emptying
What is GIP?
“Glucose-dependent insulinotropic peptide” aka “gastric inhibitory peptide”
- Increases insulin when glucose in duodenum
- Decreases gastric acid secretion: slows food coming down for insulin to take effect
- ***Much more highly stimulated with oral glucose than IV
Why is more insulin released in oral admin than IV?
GIP
What is motilin?
- Produced by M cells in SI
- Responsible for migratory motor complexes
- More prevalent in fasted state as we want to slow food down in fed for absorption
What drug is a motilin agonist?
Erythromycin
What does VIP do?
- Smooth muscle relaxation of sphincters
- Increased water / electrolyte secretion
* Increased by vagal stimulation
* Decreased by adrenergic NE
Presentation of VIPoma?
- Watery diarrhea from excess water / electrolyte secretion
NO roll in stomach?
- LES relaxation
What is loss of NO implicated in?
Achalasia
What is ghrelin?
- Produced by stomach in fasting state to remind you to eat
Disease in which ghrelin is increased?
- Prader willi syndrome from Chromosome 15 anomaly
- Causes overeating
What is IF?
“Intrinsic factor”
- Made my parietal cells in stomach and necessary for B12 absorption
- Allows for its absorption in terminal ileum
What is pernicious anemia?
- Destruction of parietal cells = decreased IF and macrocytic anemia
How does vagal stimulate parietal cells?
- ACH
3 Stimulators of Parietal cell?
- ACH: vagal binding M3 receptor
- Histamine: ECL cells via gastrin
- Gastrin
What does cimetidine do?
Block H secretion by blocking histamine receptor
How does H leave parietal cell?
H/K ATPase which is stimulated via ACH on M3 Gq via I# Ca cascade
How does histamine signal on parietal?
Via H2 receptor increasing cAMP which stimulates H/K ATPase
How do somatostatin and PGs signal on parietal cell?
Decreased cAMP decreasing H secretion
What do chief cells do?
Secrete pepsin: enzyme that aids in protein digestion
What do brunner glands secrete?
Bicarb into SI
Effects of PGs on GI?
Protect mucosa via increased bicarb and decreased H
What triggers CCK secretion?
Fats entering SI: think CCK increases bile and bile helps emulsify fats so this makes sense
What stimulates secretin?
Acid
What do D cells secrete?
Somatostatin
What releases GIP?
K cells
How is pancreatic bicarb secreted?
- Via pancreatic Cl / bicarb exchanger in pancreatic ducats cells
- Secretin increases this action
Flow dependency of pancreatic secretions?
Low flow: Cl high
High flow: bicarb high
What does alpha amylase do?
Starch digestion from pancreas
Why is trypsinogen?
Enzyme that activates all the zymogens secreted by pancreas
***Needs to first be activated by brush border enzyme enterokinase
What is enterokinase?
Brush border enzyme of SI that activates trypsinogen
Does stomach secrete anything for starch digestion?
No, only proteins and fats
What are the 3 major monosaccharides?
- Glucose
- Galactose
- Fructose
How are glucose and galactose taken up in stomach?
SGLT1 - uses Na gradient
How is fructose taken up on GI?
Glut-5
What is D xylose test?
- D xylose does not require pancreatic enzymes to be absorbed
- If problem with brush border enzymes: will not appear in bloodstream
- If problem with pancreatic enzymes: will appear in bloodstream
Where are Fe, B12, and folate absorbed?
“Iron First Bro”
Iron: duodenum
Folate: Jejunum / ileum
B12: distal ileum, needs IF
Where are bile acids absorbed?
Terminal ileum
Where are peyer’s patches found? What are they?
Lamina propria of and submucosa of illeum
- Lymphoid patches that can present antigens from GI tract
- Patches respond to antigens by secreting secretory IgA
Where are breuners glands found?
Duodenum
What can and cannot be absorbed by GLUT2?
Cannot: lactose (not a monosaccharide)
Can: Glucose, galactose, fructose
Composition of bile?
- Bile salts
- Phospholipids
- Cholesterol
- Bilirubin
- Water / ions
Rate limiting step in bile synthesis?
Cholesterol synthesis via 7-a-hydroxylase
What is a bile salt?
Bile acid conjugated with glycine or taurine to make water soluble
What is 7-a-hydroxylase?
Rate limiting step in bile synthesis that makes cholesterol
What is only way body can get rid of cholesterol?
In the bile
How is bilirubin made?
- Macs eat RBCs makin heme
- Heme oxygenase makes biliverdin -> unconjugated bilirubin
- Binds albumin to make blood soluble
- UDP-glucuronyltransferase conjugates in liver
- Excreted as bile in duodenum
Another name for unconjugated bilirubin?
Indirect
*** Both are water insoluble
Important train in unconjugated bilirubin?
Water insoluble
What happens to bile in gut?
- Gut bacteria convert to urobilinogen
- 80% excreted in stool as stercobilin = brown color
- 20% urobilinogen reabsorbed at terminal ileum
3a. 10% leaves urine as urobilin = yellow color
3b. 90% returned to liver
What does heme oxygenase do?
Makes indirect bilirubin
Cause of cleft lip and palate?
Failure of facial prominences to fuse
What is an aphthous ulcer?
Painful superficial ulcer on oral mucosa
- Arises from stress and spontaneously resolves
- Gray base surrounded by erythema
What is behcet syndrome?
- Aphthous ulcers
- Genital ulcers
- Uveitis
* from small vessel IC vasculitis
Cause of oral herpes?
HSV1
Where is HSV1 latent?
Ganglia of trigeminal nerve
What causes hairy leukoplakia?
EBV
What is bilateral inflamed parotids indicative of?
Mumps
What causes elevated amylase in mumps?
- Parotitis
2. Pancreatitis
What is a fistula?
Abnormal connection between 2 tubes
4 signs of TE fistula?
- Vomit
- Polyhydramnios
- Air in GI - distension
- Aspiration
What is an esophageal web?
- Protrusion of upper esophageal mucosa into lumen = obstruction
1. Presents with dysphagia for poorly chewed food
2. Risk of SCC
What is plummer vinson syndrome?
- Severe Fe anemia “Iron pipes / plumber”
- Esophageal web “Web / vines / vinson”
- Beefy red tongue “Jake plummer is a beefy guy”
What is zenker diverticulum?
- Outpouching of pharyngeal mucosa through muscle
- Occurs above UES at junction of esophagus and pharynx
- Caused by increased swallowing pressure in pharynx
1. Dysphagia
2. Obstruction
3. Halitosis
Is zenker true of false diverticulum?
False
What is mallory weiss?
- LONGITUDINAL laceration of mucosa at GE junctions
- Seen in severe vomit
- PAINFUL hematemesis vs. varices which is no pain
What is boerhaave syndrome?
- Rupture of esophagus = air in mediastinum
- Creates air bubbles in skin that make crackling noise
- Can be caused by mallory weiss tear
2 drainages of esophagus?
- Azygous to SVC
2. Esophageal veins -> Left gastric -> portal vein: risk of varices is here
What is achalasia?
“Without relaxation”
- Disordered esophageal motility / cannot relax LES
- Caused by damaged ganglion cells in myenteric plexus
1. Dysphagia for both solids and liquids
2. Esophageal dilation with bird beak on CXR
3. High LES pressure
4. Bad breath - Seen in chagas
What is bird beak on CXR indicative of?
Achalasia
What cells line esophagus?
Non keratinizing, squamous epithelium
When is hourglass appearance of stomach seen?
Sliding hiatal hernia
GERD presentation?
- Adult onset asthma
- Cough
- Heartburn
- Damage teeth enamel
What happens in barrett’s esophagus?
Metaplasia from non keratinizing squamous epithelium to non ciliated columnar epithelium with goblet cells
Facts for esophageal adenocarcinoma?
- Most common esophageal carcinoma
- Lower 1/3 esophagus
- Usually from barrett’s
Squamous cell carcinoma of esophagus facts?
- Middle to upper 1/3 esophagus
2. Most common worldwide
Where does cancer from esophagus spread?
Upper 1/3: cervical nodes
Middle 1/3: tracheobronchial or mediastinal nodes
Lower 1/3: Celiac / gastric nodes
What is gastroschisis?
Congenital exposure of abdominal wall usually on right side and not covered with peritoneum
- From lateral wall
Causes of acute and chronic gastritis?
Acute: burning of stomach by acid 1. Increased acid production 2. Decreased protection Chronic: 1. Autoimmune 2. H Pylori
Risks for acute gastritis?
- NSAIDs - GPs were protective
- Severe burn (curling ulcer) - decreased blood flow
- Booze
- Chemo
- Increased ICP - Cushing ulcer
How are prostaglandins protective to stomach?
- Decreased Acid
- Increased mucus
- Increased bicarb
- Increased ICP - Cushing ulcer
What is a cushing ulcer?
- Increased ICP = acute gastritis
- Increased vagal stimulation = increased ACH
- ACH = more acid from parietal cell
Difference between ulcer and erosion?
Erosion: loss of epithelium
Ulcer: loss of mucosa
What happens in autoimmune gastritis?
- Autoimmune destruction of parietal cells in body fundus
- Achlorhydria - decreased acid
- Increased Gastrin / G cell hyperplasia
- Megaloblastic anemia
- Intestinal metaplasia
Where are parietal cells found?
Fundus and body of stomach
What is intestinal metaplasia?
- Chronic gastritis leads to increased inflammatory cells in gastric lining which are not normally seen here but are seen in peyer’s patches of intestine
How does H. pylori cause gastritis? Where does it impact?
- Create ureases and proteases that damage defenses
- Antrum is most common site
Location breakout of peptic ulcer?
Proximal duodenum: 90%
Distal stomach: 10%
Causes of duodenal ulcer?
- H. Pylori, almost always
2. ZE syndrome
Which ulcer improves with meals?
Duodenum, this is because it is preparing itself for the meal and extra acid to arrive so it gets better
What happens on anterior and posterior duodenal wall rupture?
Anterior wall: - More common Posterior wall: 1. Rupture form gastroduodenal artery 2. Acute pancreatitis
Main cause of gastric ulcer?
- H Pylori 70%
- NSAIDs 20%
- Bile reflux
What ulcer worsens with meals and why?
Gastric: stomach secretes more acid to prepare for meal
Where is gastric ulcer usually found and what is risk?
- Found on lesser curvature of antrum
- Can lead to left gastric artery bleeding
Duodenal or gastric ulcer more likely malignant?
Gastric
2 types gastric carcinoma?
- Intestinal type: large irregular ulcer with heaped margins in antrum
- Diffuse type
What do nitrosamines in smoked foods give risk for?
- Intestinal type gastric carcinoma
Characteristics of diffuse gastric carcinoma?
- Signet rings cells infiltrate wall resulting in:
2. Desmoplasia causing thickening and linitis plastica
When are signet ring cells seen?
Diffuse type gastric carcinoma
What is linitis plastica indicative of?
Diffuse type gastric carcinoma
When is ulcer see in gastric cancer?
Intestinal type
Signs of gastric carcinoma?
- Acanthosis nigricans
2. Leser trelat sign
What is lesser trelat sign?
Dozens of seborrheic keratosis on skin
- Sign of gastric carcinoma
What is virchow node?
- Left supraclavicular node that drains stomach where cancer often spreads
Type of cancer causing krukenberg?
Diffuse type: signet ring cells seen
Type of cancer causing sister mary joseph?
Intestinal type
Association with duodenal atresia?
Down syndrome
What is meckels diverticulum?
- True diverticulum (all 3 layers) of bowel wall
- Failure of vitelline duct to involute
What does vitelline duct to?
- Nutrients from yolk sac to midgut early in fetus
- Forms in 4th week, gone by 7th
- Persistence = diverticulum
What does passing meconium through belly button at birth mean?
Failure of vitelline duct to close
What is being able to feel stool in belly button area indicative of?
Meckel’s diverticulum
Presentation of meckel’s diverticulum”?
- Bleeding: from heterotopic gastric mucosa that produces acid
- Volvulus
- Intussusception
- Obstruction
What is volvulus?
- Twisting of bowel along mesentery
- Obstructs blood supply = infarct
- Usually at sigmoid or cecum
Presentation of intussusception?
- Obstruction
2. Infarction - currant jelly stools
Causes of intussusception?
Adults: tumor
Kids: lymphoid hyperplasia of peyer’s patches
- Terminal illeum gets dragged into cecum
Presentation of small bowel ischemia?
- Abdominal pain
- Bloody diarrhea
- Decreased bowel sounds
Associations of celiacs?
HLA-DQ-2/8
Process of gluten?
- Most pathogenic form is gliadin
- Deamidated by tTG then presented to APCs via MHCII
- Helper Ts cause tissue damage
Celiacs presentation in kids?
- Abdominal distention
- Diarrhea
- Failure to thrive
- Dermatitis herpetiformis - IgA deposition in dermal papillae
Lab findings in celiacs?
IgA against:
- Endomysium
- tTG - (transglutaminase)
- Gliadin
Histo in celiacs?
- Flat villi
- Crypt hyperplasia
- Lymphocytic infiltrate
What is tropical sprue? Main characteristics?
Damage to small bowel villi by unknown org = malabsorption
- In tropical regions
- After infectious diarrhea
- Responds to antibiotics
* **Normally seen in jejunum and ileum
Main thing absorbed in jejunum?
Folic acid
What is whipple disease?
- Systemic tissue damage with macs loaded with whipple
- Partially destroyed orgs found in lysosomes with PAS +
- Usually in small bowel lamina propria
Presentation of whipple disease?
- Fat malabsorption
2. Steatorrhea
What are lacteals?
- Areas for absorption of chylomicrons found in lamina propria of SI villi
- Drain to lymphatics
- Chylomicrons made in enterocytes surrounding LP
What is lamina propria of of SI loaded with macs indicative of?
Whipple disease
What is abetalipoproteinemia?
- AR deficiency of apolipoprotein B48/100
What is B 48 required for?
Creation of chylomicron
What is B100 required for?
LDL / VLDL
What is positivity for chromogranin indicative of?
Carcinoid tumor
Most common site of carcinoid tumor?
Small bowel: chromogranin positive
What does carcinoid tumor usually secrete?
- Serotonin: only presents in liver because otherwise 5HT is draining to liver which just metabolizes it
What breaks down 5HT in liver?
MAO: breaks it down into 5-HIAA which is seen in urine
What is 5-HIAA in urine indicative of?
Carcinoid tumor
Presentation of carcinoid syndrome?
- Bronchospasm
- Diarrhea
- Flushing of skin
- Right sided fibrosis of heart valves: deposition of collagen = pulmonary stenosis and tricuspid regurg
Why doesn’t carcinoid tumor cause left sided fibrosis?
Lungs have MOA which breaks down MAO so fibrosis is not seen on the left side
Cause of appendicitis?
Obstruction of appendix by lymphoid hyperplasia or fecalith
Wall involvement in IBD?
Ulcerative: mucosal/submucosal ulcers
Crohn’s: full thickness with knife like fissures
Location in IBD?
Ulcerative: Continuous from rectum to colon
Crohn’s: Mouth to anus with skip lesions, ileum most common
Symptoms of IBD?
Ulcerative: left pain with blood diarrhea
Crohn’s: right pain, non bloody diarrhea
Inflammation in IBD?
Ulcerative: Crypt abscesses with neuts
Crohn’s: Lymphoid aggregates with granulomas
Gross appearance of IBD?
Ulcerative: Pseudopolyps, loss of haustra, lead pipe
Crohn’s: Cobblestone mucosa, creeping fat, strictures, string sign
What are crypt abscesses with neuts indicative of?
Ulcerative colitis
IBD complications?
Ulcerative: toxic megacolon, carcinoma
Crohn’s: Malabsorption, calcium ox stones
What is smoking protective against?
Ulcerative colitis
When is P-anca seen in stomach?
- Ulcerative colitis
- Churg strauss
- Microscopic polyangiitis
What is hirschsprung? Association?
- Defective relaxation and peristalsis of rectum and distal sigmoid
- Congenital failure of ganglion cells to descend
- Associated with Downs
Presentation of Hirschsprung?
- Failure to pass meconium
- Empty rectum on DRE
- Bowel dilation
- Rectal suction with lack of ganglion cells
What are colonic diverticula?
- Outpouching of mucosa and submucosa through muscular layer
- Caused by increased wall stress usually occurring where vasa recta cross
Complications of diverticula?
- BRBPR
- Fistula
- Diverticulitis
What is angiodysplasia?
- Acquired malformation of mucosal / submucosal capillary beds
- Usually in right colon and cecum due to high wall tension
- Presents as hematochezia
What do high stress in left and right colon caus?
Both present with hematochezia
Left: Diverticula
Right: angiodysplasia
What is hereditary hemorrhagic telangiectasia?
- Genetic thin walled vessels in GI and nasopharynx
Cause and location of ischemic colitis?
- Splenic flexure due to atherosclerosis of SMA
What is a hyperplastic polyp?
- Hyperplastic glands with serrated appearance
- Left colon
- Benign with no malignant potential
What is serrated appearance indicative of?
Hyperplastic polyp - benign left colon
What is adenoma carcinoma pathway?
- APC mutation = polyp (tumor suppressor)
- KRAS
- a P53 mutation
- b increased COX expression
What protects against gastric adenocarcinoma?
Aspirin - COX is part of pathway and aspirin inhibits this
What are sessile and pedunculated polyps and risk?
Sessile: flat growth, higher risk
Pedunculated: like mushroom
Histology in adenocarcinoma and risk?
Villous: high risk (villous = villain)
Tubular: low risk
What is FAP?
“Familial adenomatous polyposis”
- Inherited APC mutation on chromosome 5
- 1000s of colonic polyps
- Prophylactic colon resection
What is gardner syndrome?
- FAP
- Osteomas
- Fibromatosis
What is turcott syndrome?
- FAB
- Glial tumors
- Meduloblastomas
What is peutz jeghers syndrome?
- Hamartomatous GI polyps
- Mutocutasenous hyperpigment on lips, oral, genitals
- Increased risk for many cancers
What is MSI pathway?
“Microsatellite instability pathway”
- Instability seen in DNA replication that can lead to cancer
What is HNPCC?
“Hereditary non polyposis colorectal carcinoma”
- Inherited mutations in DNA repair
- Carcinomas arise de novo
Presentation of left sided GI carcinoma?
“Napkin ring lesion”
- Decreased tool caliber
- LLQ pain
- Blood in stool
- *Adenoma carcinoma sequence
Right sided GI carcinoma presentation?
“Raised lesion”
- Fe deficiency anemia
- Microsatellite sequence
WHat is CEA tumor marker for?
Progress / response of colon cancer
What is finely granular, large, hepatocytes with pale pink cytoplasm indicative of?
HBV
What does ventral pancreatic bud become?
- Main pancreatic duct
2. Uncinate process
What is adenosine demainase deficiency seen in?
SCID: Both B and T cell deficiency
What is deficient in SCID?
Adenosine deaminase
What cholesterol, bile salt, and phosphatidylcholine levels lead to gallstones?
Cholesterol: high
Bile salts: low
Phosphatidylcholine: low
Difference in cause of proximal and distal duodenal atresia?
Proximal: failure of recanalization
Distal: Vascular occlusion in utero
What does IL8 do?
- Attracts neuts and induces phagocytosis
What does C3a/C5a do?
C3: recruits eos/basos
C5: recruits neuts
What does IL3 do?
Bone marrow stimulation and growth
What does IL10 do?
Antiinflammatory from macs and TH2
Landmark for appendix?
Taenia coli
Risk of high triglycerides?
Acute pancreatitis
2 most common causes of acute pancreatitis?
- Booze
2. Gallstones
How does staph cause food poisoning?
Preformed exotoxin
How does C diff toxin work?
Toxin A/enterotoxin:
Toxin B/cytotoxin:
* both enter cell and disregulated cytoskeletal stability
Strongyloides appearance in stool?
Rhabidiform larvae
Vein in gastric varices?
Short gastric / splenic
What bleeds in perforation of posterior duodenum?
Gastroduodenal artery
What is seen in cholera diarrhea?
Flecks of mucus and, sloughed epithelial cells, no leukocytes
Most common cancer in liver?
Metastasis
Chrons hypothesis?
TH1 overactivity
What acid base abnormality does vomit lead to?
Metabolic alkalosis
What does exocrine pancreas do?
Digestive enzymes
Etiology of acute pancreatitis?
- Premature activation of trypsin causing other enzymes to be activated and causing autodigestion of pancreatic parenchyma
Appearance of prancreas in acute pancreatitis?
- Liquefactive necrosis
- Extensive hemorrhage
- Fat necrosis and saponification
2 most common causes acute pancreatitis?
- Alcohol - contracts spincter of oddi
- Gallstones
- Trauma
- Hypercalcemia
- Hyperlipidemia
- Drugs
- Scorpions
- Mumps
- Posteriors duodenal ulcer - head of pancreas sits here
Presentation of acute pancreatitis?
- Epigastric abdominal pain radiating to back
- Nausea / vomit
- HYPOcalcemia
- Elevated amylase and lipase
- Periumbilical and flank hemorrhage
2 things that could cause increased amylase?
- Pancreatitis
2. Damage to salivary gland
Complications of pancreatitis?
- Shock
- Pancreatic pseudocyst
- Abscess
- DIC - enzymes eat coag factors
- ARDS - enzymes eat alveolar lining
What is pancreatic pseudocyst?
- Seen in acute pancreatitis
- Fibrous tissue surrounding areas of necrosis and pancreatic enzymes to wall them off
- Presents with:
1. Abdominal mass
2. Persistence of amylase enzyme
3. Rupture
Causes of acute pancreatitis?
- CF: kids
2. Booze
Signs of pancreatic insufficiency / chronic pancreatitis?
- Malabsorption
- Steatorrhea
- Fat soluble vitamin deficiencies
- TIIDM
- Calcification
* *Amylase and lipase not elevated as pancreas is destroyed
What does pancreatic carcinoma arise from?
Ducts
Risks for pancreatic carcinoma?
- Smoking
2. Chronic pancreatitis
Signs of pancreatic carcinoma based on location?
Head: 1. Obstructive jaundice 2. Pale stools 3. Palpable gall bladder Body / Tail: 1. Secondary diabetes
Serum tumor marker for pancreatic cancer?
Ca - 199
What is ca 199 tumor marker for?
Pancreatic carcinoma
Cause of biliary atresia?
Failure to form extrahepatic bile ducts
Presentation of biliary atresia?
- Biliary obstruction
Increase / decrease in what can cause cholelithiasis?
Increased: 1. Bilirubin 2. Cholesterol Decreased: 1. Phospholipids (lecithin) (helps solubilize cholesterol) 2. Bile acids
2 types of gallstones?
- Cholesterol stones
2. Bilirubin stones
What is cholestyramine?
- Lipid lowering agent that binds bile acids
- Increases risk for gallstones because of this
How does stasis cause bili gallstones?
- Allows bacteria to flourish
- Bacterio unconjugated bili
- Deconjugated is not soluble = stones
Cholesterol stones radiolucent or opaque? Bilirubin?
Cholesterol: Lucent
Bilirubin: Opaque
Risk for cholesterol stones?
- Age
- Estrogen - Increases HMG CoA reductase
- Increases cholesterol uptake in hepatocytes via more receptor expression - Cirrhosis
- Crohn’s - damages terminal ileum - decreased bile acids
- Clofibrate
Risk for bili stones?
- Extravascular hemolysis - increased unconjugated bilirubin
- Biliary tract infection: causes deconjugation
Breakdown path of hemoglobin
Broken down into:
- Heme: which is broken into
a. Iron (recycled)
b. Protoporphyrin: becomes unconjugated bili (UCB) - Globin
- Broken into AAs which are recycled
Complications of gallstones?
- Biliary colic
- Cholecystitis
- Ascending cholangitis
- Gallstone ileus
- Gallbladder cancer
What is biliary colic?
- Waxing / waning RUQ pain from gallbladder contraction against stone in cystic duct
Acute cholecystitis presentation?
- RUQ pain radiating to right shoulder
- Fever / elevated WBC
- Increased alkaline phosphatase
What is porcelain gallbladder complication of?
Chronic cholecystitis
What is RUQ pain after eating indicative of?
Acute cholecystitis: bladder is trying to contract to release bile
Cause of jaundice?
Serum bili >2.5
What is urobilinogen?
- Enteric flora in GI act on conjugated bilirubin when released in bowel
- Makes poo brown / pee yellow
Why does ineffective erythropoiesis cause jaundice?
Macs are destroying poorly made RBCs
Do hemolysis and ineffective erythropoiesis case elevated conjugated or unconjugated?
- Unconjugated as system is overwhelmed
Whats happening in physiologic jaundice of newborn?
- Baby has deficiency conjugating due to low UGT
What is kernicterus?
- UCB is fat soluble so can deposit in basal ganglia if too much seen in baby
- Causes neurologic deficits and death
What does phototherapy do?
Makes UCB water soluble: ISNOT conjugating
What is gilberts?
- Genetically low UGT = increased UCB during stress
- Normally not clinically significant
Two spectrums of decreased UGT in adults?
- Gilberts: mild
2. Crigler: severe
What is Crigler Najar?
- Absent UGT
- High UCB
- Kernicterus and death
What is Dubin Johnson?
Dubin “think dubin = dumpin” problem with dumbing bili
- Deficiency in canalicular bili transport protein
- Increase in CB as conjugating system is fine
- Liver is pitch dark
What is pitch dark liver indicative of?
Dubin Johnson syndrome: think that it’s getting dark from all the bile that is accumulating in there
What is rotor syndrome?
Same as dubin Johnson but lacks black liver
Signs of obstructive jaundice?
- Jaundice
- Pruritis: bile acids leak and deposit in skin
- Xanthomas / HYPERcholesterolemia: cholesterol is leaking from bile
- Pale stool as bile cant get in bowel
- Steatorrhea
- Deficient fat soluble vitamins
- Dark urine: CB is water soluble
Break out of bili in hepatitis?
- Both UCB and CB as both hepatocytes and ducts are being damaged
3 causes viral hepatic?
- Hepatitis virus
- CMV
- EBV
Presentation of acute hepatitis?
- Mixed jaundice
- Dark urine
- ALT > AST
Where is inflammation in Acute / chronic hepatitis?
Acute: 1. Within portal tracts 2. Between hepatocytes Chronic: 1. Portal tracts
Mechanism of hepatocyte destruction in hepatitis?
- Viral antigens presented in MHCI
- CD8 cells perform killing
Routes of HAV, HEV? What is chronic state like?
HAV: fecal oral, travelers
HEV: fecal oral, contaminated water
*No chronic state seen
HEV in pregnancy?
Fulminant hepatitis with liver failure / necrosis
Which acute hepatitis has vaccine?
HAV
First serum marker to rise in acute HBV?
HBsAg
- If > 6 months = chronic
- Gone if infection is resolved
Marker of acute HBV battle?
IgM vs. core antigen
*If IgG, chronic
How to tell if resolved chronic HBV or immunized?
Resolved: IgG vs. core and surface
Vax: only surface IgG
What indicates HBV infectivity?
Envelop antigen
How to tell if HCV infx?
Viral RNA
HDV?
Only can occur if infected with HBV
- Acquire at later time: coinfection, less sever
- Acquire at same time: super inx, very severe
Histo in cirrhosis?
- Disruption of parenchyma by broad bands of cirrhosis and regenerative nodules of hepatocytes
What mediates fibrosis in cirrhosis?
- TGF-beta from stellate cells
- Lies below endothelial cells that line sinusoids
Funny things that happens in splenomegaly?
Hypersplenism: consumes RBCs and platelets
Why does cirrhosis cause hyperestrinism and what are results?
- Liver is normally removing estrogen from blood:
1. Gynecomastia
2. Spider angioma
3. Palmar erythema
Protein impacts of cirrhosis?
- HYPOalbuminemia
- Coagulopathy: decreased clotting factors
- Can no longer activate vitamin K
* *Increased PT AND PTT
Is fatty liver reversible?
Yes
What mediates damage in alcoholic hepatitis?
Acetaldehyde
Presentation of alcoholic hepatitis?
- Swelling / ballooning of hepatocytes
- Necrosis and acute inflammation
- Mallory bodies: damaged intermediate filaments in hepatocytes
What are mallory bodies indicative of?
Alcoholic hepatitis: from damaged intermediate filaments in hepatocytes
What is AST > ALT in alcoholic hepatitis?
- Acetaldehyde is mitochondrial poison
- AST is located in mitochondria
What is hemochromatosis / siderosis?
Hemochromatosis: excess Fe in body
Siderosis: deposition in tissues
*Damage is being caused by free radical deposition
Gi handling of Fe?
- Enterocytes take up and store Fe
- Only passes to blood if body says its needed
What happens in primary hemochromatosis?
- No regulation of Fe moving from enterocytes to blood
- Excess Fe now is deposited in tissues
Mutation in primary hemochromatosis?
HFE gene / C282Y
Cuase of secondary hemochromatosis?
Transfusions: body has no way to get rid of Fe
Presentation of hemochromatosis?
- Bronze skin
- Cirrhosis
- Secondary diabetes
- Arrhythmia
- Gonadal dysfunction
Lab values in hemochromatosis?
Ferritin: increased
TIBC: decreased
Serum Fe: increased
% Saturation: increased
Diagnosis of hemochromatosis?
- Liver biopsy showing brown pigment turning blue on prussian stain
- If does not turn blue, it is lipofuscin from normal damage
Defect in wilson’s? What does it cause?
- ATP7B gene involved in ATP mediated hepatocyte copper transport
1. Decrease Cu secretion in bile
2. Decreased Cu incorporation in ceruloplasmin
What is ceruloplasmin?
- Molecule that carries copper in blood
- Cannot integrate copper in wilson’s disease
Presentation of wilson’s?
Presents in childhood:
- Variety of neurologic symptoms
- Kayser fleischer rings in cornea
- Hepatocellular carcinoma
What are kayser fleischer rings seen in?
Wilsons
Treatment of wilson’s disease?
D-penicillamine: copper chelator
What is decreased serum ceruloplasmin seen in?
Wilson’s
What is primary biliary cirrhosis?
- Autoimmune, granulomatous destruction of intrahepatic bile ducts
- Antimitochondrial Ig is diagnostic
What is autoimmune, granulomatous destruction of intrahepatic bile ducts?
- Primary biliary cirrhosis
What is antimitochondrial Ig diagnostic of?
Primary biliary cirrhosis
Presentation of primary biliary cirrhosis?
- Obstructive jaundice
2. Liver cirrhosis
What is primary sclerosing cholangitis?
“Periductal fibrosis with onion skinning”
- Inflammation / fibrosis of intra/extrahepatic bile ducts
- Uninvolved areas are dilated = beaded appearance on imaging
- P-ANCA positive
- Causes conjugated jaundice
- Seen in ulcerative colitis
What is the following indicative of:
“Periductal fibrosis with onion skinning”
Primary sclerosing cholangitis
Associations of Primary sclerosing cholangitis
Ulcerative colitis
- p-ANCA
What is Reye syndrome?
- Fulminant hepatitis in child who takes aspirin with viral illness
- Likely due to mitochondrial damage
Reye presentation?
- Nausea / vomit
- Elevated liver enzymes
- HYPOglycemia
- Coma / death
Causation of hepatic adenoma?
- Oral contraceptive use: resolves on cessation `
- Risk of rupture in pregnancy which E2 is high
What is aflatoxin risk for?
Hepatocellular carcinoma
- Induces P 53 mutations
What is budd chiari?
- Thrombosis of hepatic vein often from tumor invasion
- Ascites and painful hepatomegaly seen
Tumor marker for hepatocellular carcinoma?
AFP
What is AFP tumor marker for?
Hepatocellular carcinoma
What CN moves through parotid gland?
VII: as such tumor in parotid can = facial pain, paralysis
Another name for achalasia?
Megaesophagus: from chagas
2 instances in which eosinophils are seen?
- Allergies
2. Parasitic infections
When is trachealization of esophagus seen?
Eosinophilic esophagitis
Medication causing esophagitis?
Bisphosphonates
Difference in HSV and CMV esophageal ulcers?
CMV: linear
HSV: punched out
Cancer risk in H pylori?
MALT lymphoma
What is menetrier disease?
Gastric hypertrophy associated with:
- Increased mucus cells
- Parietal atrophy
- Protein loss
* *Rugae are so hypertrophic they look like rain
What to suspect if ulcers seen further down SI than in duodenum?
ZE syndrome
When is hypertrophy of brunner’s glands seen?
Duodenal ulcers
Blood supply to lesser curvature of stomach?
Left gastric
Blood supply to greater curvature of stomach?
Gastroepiploic artery
Blood supply to duodenum?
Gastroduodenal artery: rungs along posterior
What does sudan B stain test for?
Fat in stool
D xylose test in celiacs?
Decreased as BB enzymes are destroyed so can’t absorb as much
What does lactose break into?
Glucose and galactose
Hydrogen breath test relevance in lactose intolerance?
Large rise in these patients post lactose as they colonic bacteria ferment lactose making H and they cannot break it down
Folate or B12 show neuro symptoms?
B12
When is string sign seen?
Crohn’s
When is cobblestone mucosa seen?
Crohn’s
What are the extra intestinal manifestations of IBD?
- Pyoderma gangrenosum: rash
- Uveitis
- Erythema nodosum
- Oral ulcers
- Arthritis
- Ca / ox stones: Crohns
Where is mcburneys point?
1/3 way between anterior superior iliac spine and umbilicus
- Appendicitis pain often presents here
Tissue often found in meckel diverticulum?
- Gastric
2. Pancreatic
Diagnosis of Meckel’s
Pertechnetate study
- Molecules are taken up by the ectopic parietal cells in the diverticulum
What does pertechnetate study diagnose?
Meckel’s
- Molecules are taken up by the ectopic parietal cells in diverticulum
Hirschsprung presentation?
- No stools
- Bilious vomit
- Distended abdomen
* *Often seen in down’s syndrome
What is ileus? Causes?
HYPOmotility of bowel
- Opiates
- HYPOkalemia
- Post opp
When is meconium ileus seen?
CF
“CLAX TPAG” mnemonic?
Syndrome: Cockayne Lynch Ataxia Telangiectasia Xeroderma Pigmentosum Mutation: Transcription coupled nucleotide excision repair Post replicative repair ATM gene defect Genome wide repair
What is lynch syndrome?
aka “HNPCC”
- Defect in Post replicative mismatch repair
- Due to methylation of MHS1, 2, or 6
- Leads to colorectal carcinoma of right colon
Other cancers seen in lynch?
- Endometrial
- Skin
- Ovarian
Colorectal polyp that does not have risk for cancer?
Hyperplastic
2 disease processes with increased alkaline phosphatase?
- Biliary obstruction
- Bone disease
* ***Use GGT to distinguish as is specific to alcoholic liver
Which zone at risk for alcoholic liver?
Zone III
What is a non smoker with panacinar emphysema and PAS+ liver lobules indicative of?
A1-antitrypsin deficiency
Type I or II crigler more serious?
Type I
Why is liver black in Dubin Johnson?
Buildup of epinephrine metabolites
Risks for cholesterol stones?
- Obesity
- Crohns
- Weight loss
- 4 Fs: fat, female, fertile, forty `
What is courvoisier sign?
- Palpable non tender gallbladder
- Obstructive jaundice
- Cancer of pancreatic head
What does prazole ending indicate?
PPIs
What kills cells with decreased or absent MHC I?
Natural killers
What makes up walls of pancreatic pseudocyst?
Fibrous tissue, granulation tissue, ABSENCE of epithelial cells
What can’t liver to with ammonia in cirrhosis?
Convert it to urea
Where are fats digest and absorbed?
Digested: duodenum
Absorbed: jejunum
Where do most anal fissures occur?
Posterior, distal to dentate
Another name for B12?
Cobalamin
What could cancer in 3rd part of duodenum compress?
SMA
Where in duodenum is ampulla and odi?
2nd part
Where would air be seen in gallstone ileus?
- Biliary tree
2. SI
Presentation of VIPoma?
- Secretory / watery diarrhea
- Achlorhydria
- HYPOkalemia
Lymphatic drainage proximal and distal to dentate?
Proximal: internal iliac and IMA
Distal: inguinal nodes
How does HBV replicate?
- DSDNA
- SSRNA
- DSDNA
What is CREST?
Calcinosis Raynauds Esophageal dysmotility Sclerodactyly Telangiectasias
What is IV bioavailability?
100% normally
Equation for oral bioavailability?
AUC oral dose / AUC IV dose
What vitamins do enteric bacteria make?
- K
2. Folate
Where is stomach attached in GI bypass?
Jejunum
What is SI intestine with large PAS foamy macs indicative of?
Whipple
Bodies protection form Giardia?
Iga and CD4+ helpers
Where can splenic pain refer to?
Shoulder
What can cause hiccups?
Phrenic nerve irritation leading to spasm of diaphragm
What causes secretin to be released?
Duodenal H
What is CA 125 marker for? 199?
125: ovarian
199: pancreatic
Signs of carcinoid syndrome?
- Watery diarrhea
- Flushing
- Bronchospasm
- Right sided valvular plaques
Treatment for carcinoid?
Octreotide: somatostatin analog
**Also works in VIPomas
How is secretin used diagnostically?
Normal: decrease gastrin and increases bicarb
ZE: Increases gastrin