GI Flashcards
ursodiol MOA
Nontoxic bile acid. Increases bile secretion + decreases cholesterol secretion and absorption.
ursodiol clinical use
PBC + gallstone prevention or dissolution.
Orlistat MOA
inhibits gastric and pancreatic lipase, thus leading to decreased breakdown and absorption of dietary fats.
Orlistat AE’s
steatorrhea + decreased absorption of fat-soluble vitamins.
metoclopramide MOA
D2 receptor antagonist. Increases resting tone, contractility, LES tone, motility. Does not influence colon transport time.
metoclopramide clinical use
diabetic and postsurgery gastroparesis, antiemetic
metoclopramide contraindications
digoxin + diabetic agents + SBO or Parkinson disease (due to D2 receptor blockade)
metoclopramide AE’s
parkinsonian effects, tardive dyskinesia, restlessness, drowsiness, fatigue, depression, diarhea.
ondansetron MOA
serotonin antagonist + decreases vagal stimulation
ondansetron AE’s
headache + constipation + QT interval prolongation
Loperamide MOA
agonist at mu-opioid receptors; slows gut motility. Poor CNS penetration (low addictive potential)
loperamide AE’s
constipation + nausea
Sulfasalazine – MOA, clinical use, SE’s
Sally Westcott in a sulfur geiser/sulfasalazine. Pyramid with sulfur geiser on top on right + tree with bark and hailing on it/MOA = combination of sulfapyridine (antibacterial) + 5-aminosalicylic acid (anti-inflammatory). Bacteria on counter throwing lasso around her/activated by colonic bacteria. Rachel in wheelchair next to counter/can cause drug-induced lupus. Riding a dead sperm/toxicity = malaise + nausea + sulfonamide toxicity + reversible oligospermia. /clinical use = UC + Crohn disease.
lactulose
osmotic laxative
osmotic laxatives AE’s
diarrhea, dehydration.
octreotide MOA
long-acting somatostatin analog; inhibits secretion of various splanchnic vasodilatory hormones.
Octreotide AE’s
nausea, cramps, steatorrhea + increased rick of cholethiasis due to CCK inhibition.
misoprostol MOA
PGE1 analog. increased production and secretion of gastric mucous barrier, decreases acid production.
misoprostol mechanism as abortifacent
Ripens cervix
Other use of misoprostol.
Maintains PDA.
misoprostol AE’s
diarrhea
bismuth, sucralfate MOA
binds to ulcer base, providing physical protection and allowing HCO3- secretion to reestablish pH gradient in the mucous layer.
another use for bismuth, sucralfate
travelers’ diarrhea.
shared AE of all antacids
hypokalemia
aluminum hydroxide AE’s
constipation + hypophosphatemia + proximal muscle weakness + osteodystrophy + seizures
calcium carbonate AE’s
hypercalcemia (milk-alkali syndrome) + rebound acid production
magnesium hydroxide AE’s
Harvey milk (sean penn) from movie milk in middle of room giving magnus who’s benchpressing a blowjob: he’s shitting on a towel + IV pole next to him + is being shocked + riding a mini motorcycle/SE’s = diarrhea + hyporeflexia + hypotension + cardiac arrest.
What is a proton pump?
H+/K+ ATPase in stomach parietal cells.
ZES treatment
PPI
PPI AE’s
Nate is banging Heidi on the table + magnus strong man on the table + carson with his ski gear at other end of table/SE’s = increased risk of C. diff infection + decreased serum Mg2+ with long-term use + atrophic gastritis + carcinoid tumors + headaches + GI disturbances. Rest of seats filled with skeletons/associated with osteoporosis and osteoporotic hip fractures (decreases calcium absorption;calcium carbonate requires an acidic environment for proper absorption).
H2 blocker MOA
reversible block of histamine H2 receptors –> decreased H+ secretion by parietal cells.
H2 Blocker AE’s
- Cimetidine is the primary concern. Others are relatively free of these effects.
- CYP450 inhibitor + antiandrogen effects + can cross BBB (confusion, dizziness, headaches) and placenta + decreases renal excretion of creatinine.
ranitidine AE
Decreases renal excretion of creatinine.
Foregut region
pharynx t oduodenum
midgut region
duodenum to proximal 2/3 of transverse colon.
hindgut region
distal 1/3 of transverse colon to anal canal above pectinate line.
Midgut development
6th week–physiologic midgut herniates through umbilical ring.
10th week–returns to abdominal cavity + rotates around SMA, total 270 counterclockwise.
Defect in rostral fold closure
Sternal defects
Defect in lateral fold closure
Omphalocele, gastroschisis
defect in caudal fold closure leads to…
bladder exstrophy
gastroschisis
extrusion of abdominal contents through abdominal folds (typically right of umbilicus); not covered by peritoneum.
Most common tracheoesophageal anomalies
esophageal atresia with distal tracheoesophageal fistula (85%)
why does cyanosis occur with esophageal atresia?
Secondary to laryngospasm (to avoid reflux-related aspiration).
H-type esophageal atresia
Pure TEF. see FA
jejunal and ileal atresia pathophys
disruption of mesenteric vessels –> ischemic necrosis –> segmental resoprtion.
characteristic sign of jejunal and ileal atresia.
Bowel discontinuity or “apple peel.”
epidemiology of hypertrophic pyloric stenosis
Most common cause of gastric outlet obstruction (1:600).
hypertrophic pyloric stenosis RF
Exposure to macrolides.
hypertrophic pyloric stenosis acid/base disturbance
hypokalemic hypochloremic metabolic alkalosis (vomiting of gastric acid and subsequent volume contraction).
pancreas embryology
Derived from foregut. Ventral pancreatic buds contribute to uncinate process and main pancreatic duct. Dorsal pancreatic bud alone becomes body, tail, isthmus, and accessory pancreatic duct. Both ventral and dorsal buds contribut to pancreatic head.
annular pancreas
ventral pancreatic bud abnormally encircles 2nd part of duodenum; forming ring of pancreatic tissue that may cause dudoenal narrowing and *nonbilious vomiting.
Pancreas divisum and timeframe
Ventral and dorsal parts fail to fuse at 8 weeks. Common and mostly asymptomatic, but may cause chronic abdominal pain and/or pancreatitis.
pancreas anatomy
codebook
SADPUCKER notes
Aorta AND IVC
2nd-4th parts of duodenum
Pancreas (except tail)
Esophagus (thoracic portion)
falciform connects
Liver to anterior abdominal wall
falciform contains
ligamentum teres hepatis
ligamentum teres hepatis derived from…
fetal umbilical vein
falciform derivative of…
ventral mesentery
hepatoduodenal connects…
liver to duodenum
hepatoduodenal
portal triad
pringle maneuver
Compressing hepatoduodenal ligament between thumb and index finger in omental foramen to control bleeding.
hepatoduodenal borders the…
omental foramen
omental foramen connnects
The greater and lesser sacs.
gastrohepatic connects
liver to lesser curvature of stomach
gastrohepatic contains
- gastric arteries
- separates greater and lesser sacs on the right.
what do you need to cut to access the lesser sac?
gastrohepatic ligament
gastrocolic connects… forms..
- greater curvature and transverse colon.
- part of greater omentum.
gastrocolic contains
gastroepiploic arteries
What separates greater and lesser sacs on the left?
gastrosplenic
gastrosplenic connects…forms…
- greater curvature and spleen
- part of greater omentum
gastrosplenic contains
short gastrics, left gastroepiploic
splenorenal connects….
Spleen to posterior abdominal wall.
Splenorenal contains
splenic artery and vein + tail of pancreas
Layers of gut wall
inside to outside -- MSMS Mucosa Submucosa Muscularis externa Serosa
Mucosa contains…
epithelium, lamina propria, muscularis mucosa.
submucosa includes…function..
- Submucosal nerve plexus (Meissner).
- Secretes fluid.
Muscularis externa includes…
Myenteric nerve plexus (Auerbach)
serosa caveat
Called serosa when intraperitoneal, adventitia when retroperitoneal.
erosions vs. ulcers
Ulcers can extend into submucosa, inner or outer muscular layer. Erosions are confined to mucosa.
Stomach basal rhythm
3 waves/min
Duodenum basal rhythm
12 waves/min
Ileum basal rhythm
8-9 waves/min
Muscularis composition
Inner circular layer, myenteric nerve plexus (Auerbach), outer longitudinal layer
Brunner glands
HCO3- secreting cells of submucosa.
Duodenum contains
Brunner glands + cytps of Lieberkuhn + villi and microvilli
histology of jejunum
Plicae circularis and crypts of Lieberkuhn.
Peyer patches
Lymphoid aggregates in lamina propria, submucosa.
Where are peyer patches?
Ileum
Ileum histology
peyer patches + plicae circulares + crypts of lieberkuhn.
Where are the largest number of goblet cells in the small intestine?
Ileum
Colon histology
Crypts of Lieberkuhn but no villi; abundant goblet cells.
abdominal aorta branches rule
Arteries supplying GI structures branch anteriorly. Arteries supplying non-GI structures branch laterally and posteriorly.
Middle suprarenal anatomic location.
T12
celiac trunk anatomic location.
T12
Fist lumbar anatomic location
L1
Renal anatomic location
L1
SMA anatomic location
L1
Gonadal anatomic location
Just above L2
IMA anatomic location
L3
Bifurcation of abdominal anatomic location
L4 (biFOURcation)
Common iliacs anatomic location
L5
SMA artery syndrome
1) presentation
2) anatomy
3) scenario
1) Intermittent intestinal obstruction symptoms (primarily postprandial pain)
2) Transverse (3rd) portion of duodenum is compressed between SMA and aorta.
3) Conditions associated with diminished mesenteric fat (eg, low body weight/malnutrition).
Foregut
1) arterial supply
2) PS innervation
3) vertebral level
4) structures supplied
1) Celiac
2) Vagus
3) T12/L1
4) Pharynx (vagus nerve only) and lower esophagus (celiac artery only) to proximal duodenum; liver, gallbladder, pancreas, spleen (mesoderm)
Midgut
1) arterial supply
2) PS innervation
3) vertebral level
4) structures supplied
1) SMA
2) vagus
3) L1
4) distal duodenum to proximal 2/3 of transverse colon
Hindgut
1) arterial supply
2) PS innervation
3) vertebral level
4) structures supplied
1) IMA
2) Pelvic
3) L3
4) distal 1/3 transverse colon to upper portion of rectum.
TIPS procedure
Transjugular intrahepatic portosystemic shunt (TIPS). Creates a shunt between portal vein and hepatic vein, thus relieving portal HTN by shunting blood to the systemic circulation, bypassing the liver.
Varices seen with portal hypertension
(gut, butt, and caput (medusa) –> esophageal, rectal (anorectal varices), caput medusa
portosystemic rectal anastomosis
superior rectal with middle and inferior rectal.
caput medusae anastomosis
Paraumbilical with small epigastric veins of the anterior abdominal wall.
esophageal varices anastomosis
left gastric with azygos
pectinate (dentate) line
Formed where endoderm (hindgut) meets ectoderm.
Venous drainage above pecinate line
Superior rectal vein –> ifnerior mesenteric –> portal system
lymphatic drainage above pectinate line
internal iliac lymph nodes
venous drainage below pectinate line
inferior rectal vein –> internal pudendal vein –> internal iliac vein –> common iliac vein –> IVC
lymphatic drainage below pectinate line
Superficial inguinal nodes.
Anal fissure RF’s
low fiber diet + constipation.
Kupffer cells
Specialized macrophages that form the lining of sinusoids
Hepatic stellate (Ito) cells 1) location 2) function
1) space of Disse
2) store vitamin A (when quiescent), produce ECM when activated.
intermediate zone, pericentral vein (centrilobular) zone, intermediate zone
Zone 1 = periportal zone
Zone 2 = intermediate zone
Zone 3 = pericentral vein (centrilobular) zone
Site of alcoholic hepatitis
Zone III
yellow fever affects…
zone II
ingested toxins (eg cocaine) affect….
Zone I
zone affected 1st by ischemia
Zone III (farthest from arterial supply)
zone affected 1st by viral hepatitis
Zone I
ampulla of vater and 2) clinical significance
1) little widened space behind sphincter of oddi in head of pancreas (FA 347)
2) gallstones that lodge here an block both the common bile and pancreatic ducts causing “double duct sign” –> both cholangitis and pancreatitis.
cystic duct
Duct that drains gallbladder
painless juandice
pancreatic adenocarcinoma (usually ductal) in head of pancreas that causes of obstruction of common bile duct.
femoral region organization
NAVeL –> nerve, artery, vein, lymphatics
femoral triangle
contains femoral nerve, artery, vein
femoral sheath
fascial tube 3-4 cm below inguinal ligament. Contains femoral vein, artery, and canal (deep inguinal lymph nodes) but NOT femoral nerve.
femoral triangle borders
- superiorly by inguinal ligament.
- medially by medial border of adductor longus.
- laterally by medial border of sartorius muscle.
superficial inguinal ring
External obie standing in the middle of a golden ring/formed by opening in the external oblique muscle aponeurosis.
Deep inguinal ring
• Code: hole down to china beneath trannies/opening in the transversalis fascia.
Layers of inguinal canal
Obie Spear on outside, closer to bank with stomach covered in big sperm/external spermatic fascia derived from external oblique. Obie hanging from inside pulling testicles up with a rope/cremasteric muscle and fascia derived from internal oblique. Line of trannies with sperm that have buried into their stomachs/internal spermatic fascia derived from transversalis fascia.
Site of protrusion of direct hernia
abdominal wall
Site of protrusion of indirect hernia
deep inguinal ring
conjoined tendon
formed by transversus abdominis muscle + internal oblique muscle
umbilical hernia defect location
defect at linea alba
incarceration
hernia that can’t be reduced.
strangulation
hernia that becomes ischemic and necrotic
presentation of complicated hernias
tenderness, erythema, fever.
structure defective in congenital diaphragmatic hernia and usual location
- pleuroperitoneal membrane.
- left side (no liver for protection)
Site of protrusion of direct inguinal hernia
Hesselbach triangle. Bulges directly through abdominal wall.
Other details of direct inguinal hernia
- goes through external (superficial) inguinal ring only.
- covered by external spermatic fascia.
- usually in older men.
Femoral hernia epidemiology
usually females.
femoral hernia protrusion
Below inguinal ligament through femoral canal below and lateral to pubic tubercle.
caveat about femoral hernias
More likely to incarcerate or strangulate.
Inguinal (hesselbach) triangle
Inferior epigastric vessels, lateral border of rectus abdominis, inguinal ligament
Gastrin source and location
G cells (**antrum of stomach, duodenum)
gastrin action
increases gastric H+ secretion, growth of gastric mucosa, gastric motility.
gastrin 1) increased by 2) decreased by
1) stomach distention/alkalinization, amino acids, peptides, vagal stimulation via gastrin-releasing peptide (GRP)
2) ph
what increases gastrin production?
chronic PPI use, chronic atrophic gastritis (H pylori), ZES
Somatostatin source
D cells (pancreatic islets, Gi mucosa)
somatostain actions
decreases gastric acid and pepsinogen secretion + pancreatic and small intestine fluid secretion + gallbladder contraction + insulin and glucagon release
somatostain regulation
increased by acid, decreased by vagal stimulation.
CCK source
I cells (duodenum, jejunum)
CCK action
Increases pancreatic secretion + gallbladder contraction. Decreases gastric emptying. Increases sphincter of oddi relxation.
CCK regulation
Increased by fatty acids, amino acids.
How does CCK cause pancreatic secretion
Acts on neural muscarinic pathways.
Secretin source
S cells (duodenum)
Secretin actions
Increases pancreatic HCO3- secretion + bile secretion. Decreases gastric acid secretion. Functions to neutralize gastric acid in duodenum, allowing pancreatic enzymes to function.
Secretin regulation
Increased by acid, fatty acids in lumen of duodenum.
glucose-dependent insulinotropic peptide
another name for GIP.
GIP source
K cells (duodenum, jejunum)
GIP functions
Exocrine: decreases gastric H+ secretion.
Endocrine: increases insulin release.
GIP regulation
Increased by fatty acids, amino acids, oral glucose.
Why does oral glucose lead to increased insulin compared to IV
GIP secretion.
drug that that acts as a motilin receptor agonist
erythromycin
VIP source
PS ganglia in sphincters, gallbladder, small intestine
VIP functions
Increases intestinal water and electrolyte secretion + increases relaxation of intestinal smooth muscle and sphincters.
VIP regulation
Increased by distention and vagal stimulation, decreased by adrenergic input.
Why is there increased LEs tone in achalasia?
Loss of NO secretion.
Ghrelin source
stomach
Ghrelin clinical relevance
Increased in Prader-Willi, decreased after gastric bypass surgery.
gastric acid positive regulators
histamine, ACh, gastrin
gastric acid negative regulation
somatostatin, GIP, prostaglandin, secretin.
pepsin source and function
chief cells, protein digestion