Steve Seagal's Gut Punching GI Gospel Flashcards
What is the foregut
pharynx to duodenum
What is the midgut
duodenum to proximal 2/3 of transverse colon
what is the hindgut
distal 1/3 of the transverse colon to the anal canal above the pectinate line
Developmental defects of anterior abdominal wall due to the failure of:
Rostral fold closure: sternal defects
Lateral fold closure: omphalocele, gastroschisis
Caudal fold closure: bladder extrophy
Duodenal atresia: associated with? What is it?
failure to recanalize
trisomy 21
Jejunal, ileal, colonic atresia is mostly due to
vascular accident, like superior mesenteric not developing, makes gut small and twisty, called apple peal atresia
Midgut development
6th week is when midgut herniates through umbilical ring
10th week returns to abdominal cavity and rotates around SMA
Malrotation of the midgut, omphalocele, intestinal atresia or stenosis, volvulus
Gastroschisis
extrusion of abdominal contents through abdominal folds; not covered by peritoneum
Omphalocele
persistence of herniation of abdominal contents into umbilical cord, sealed by peritoneum
Tracheoesophageal atresia
EA with distal tracheoesophageal fistula is most common: drooling, choking, vomiting with first feeding. Fistula allows air into stomach. Cyanosis is secondary to laryngospasm (spasm is to stop reflux aspiration). diagnose by NG not being able to get to stomach
H-type: is the fistula alone
Pure atresia: no gas in stomach
Congenital pyloric stenosis
Hypertrophy of the pyloris causes obstruction
palpable “olive” mass in epigastric region and nonbilious projectile vomiting at 2-6 weeks of age
treat with surgical incision
more often in first born males
Pancreas embryology
derived from foregut
ventral pancreatic buds contribute to the pancreatic head and main pancreatic duct.
uncinate process is formed by the ventral bud alone
dorsal pancreatic bud becomes everything else
Annular pancreas
ventral pancreatic bud abnormally encircles 2nd part of duodenum; forms a ring of pancreatic tissue that may cause duodenal narrowing
Problem with malrotation of ventral bud around duodenum
New born will have bilious vomiting and polyhydramnios
Pancreas divisum
ventral and dorsal parts fail to fuse at 8 weeks
Spleen embryology
arises in mesentery of stomach (hense is mesodermal) but is supplied by foregut (celiac artery)
Retroperitoneal structures
all GI structures that lack a mesentery and non-GI structures
injuries to these can cause blood or gas to build up in space
SAD PUCKER
Suprarenal glands, Aorta and ivc, Duodenum (2nd through 4th parts), Pancreas (except tail), Ureters, Colon (descending and ascending), Kidneys, Esophagus, Rectum
Falciform ligament
Connects liver to anterior abdominal wall
contains ligamentum teres hepatis
this is a derivative of ventral mesentery
Hepatoduodenal ligament
Connects Liver to duodenum
Contains the portal triad: proper hepatic artery, portal vein, common bile duct
Part of the lesser omentum
Pringle maneuver-
hepatoduodenal ligament may be compressed between thumb and index finger placed in omental foramen to control bleeding
omental foramen is what connects the lesser and greater sac
Gastrohepatic ligament
Connects liver to lesser curvature of stomach
contains the gastric arteries
separates the greater and lesser sacs on the right
may be cut during surgery to access lesser sac
Gastrocolic ligament
connects greater curvature and transverse colon
contains gastroepiploic arteries
it is part of the greater omentum
Gastrosplenic ligament
connects greater curvature and the spleen
contains short gastric arteries and left gastroepiploic vessles
Separates the greater and lesser sacs on the left
Splenorenal ligament
connects spleen to posterior abdominal wall
contains the splenic artery and vessels, tail of pancreas
Layers of the gut wall
MSMS
Mucosa- epithelium, lamina propria, muscularis mucosa
Submucosa- includes submucosal nerve plexus (meissner’s)
Muscularis externa- includes Myenteric plexus (Auerbach)
Serosa/adventitia- Serosa when intraperitoneal, adventitia when retroperitoneal
Frequency of basal electric rhythm: stomach, Duodenum, Ileum:
stomach: 3 waves/min
Duodenum: 12 waves/min
Ileum: 8-9 waves/min
Distinctive Histology of the esophagus
nonkeratinized stratified squamous epithelium
Distinctive Histology of the stomach
Gastric glands
Distinctive Histology of the Duodenum
Villi and microvilli which increase absorptive surface
Brunner glands in the submucosa
Cyrpts of Lieberkuhn
Distinctive Histology of the Jejunum
Plicae circulares and crypts of Lieberkuhn
Distinctive Histology of the Ileum
Peyer patches in the lamina propria and submucosa
plicae cirulares in the proximal ileum
crypts of Lieberkuhn
Has the largest Number of goblet cells in the small intestine
Distinctive Histology of the Colon
Colon has crypts of Lieberkuhn but no villi
numerous goblet cells
What is Superior mesenteric artery syndrome
when the transverse portion of the duodenum is entrapped between SMA and aorta
causes intestinal obstruction
GI blood supply and innervation for the Foregut
Celiac artery
Vagus parasympathetic innervation
at vertebral level T12 and L1
structures included are the proximal duodenum: liver, bladder, pancreas, spleen (mesoderm)
GI blood supply and innervation for the midgut
SMA
Vagus parasympathetic
at vertebral level L1
Structures include duodenum to proximal 2/3 transverse colon
GI blood supply and innervation for the hindgut
IMA
Pelvic parasympathetic innervation
at vertebral level L3
Structures include distal 1/3 transverse colon to the upper portion of the rectum
splenic flexure is a watershed region: what does that mean
receives blood from the terminal branches of SMA and IMA, makes it prone to ischemic damage in cases of low blood pressure because it does not have its own primary source of blood
Celiac trunk: branches
common hepatic, splenic, left gastric: make up the main blood supply of the stomach
Anal fissure
Tear in anal mucosa below the pectinate line
Pain while Pooping
Located Posteriorly since this are is Poorly Perfused
Internal hemorrhoids
receive visceral innervation and are therefore not painful
Lymph drains into deep nodes in this area
Blood flow below pectinate line
arterial supply form inferior rectal artery (branch of internal pudendal artery
Venous drainage to inferior rectal vein to internal pudendal vein to internal iliac vein to IVC
Likely cancer of GI above and below pectinate line
above you are more likely to get adenocarcinoma
below you are more likely to get squamous cell carcinoma
Blood flow above pectinate line
arterial from superior rectal which is a branch of the IMA
venous is to the superior rectal vein to the inferior mesenteric to the portal system
External hemorrhoids
below pectinate line
receive somatic innervation via inferior branch of pudendal nerve, making them painful
lymph drains to superficial inguinal nodes
3 zones of Liver anatomy
Zone 1: periportal zone: affected first by viral hepatitis, Ingested toxins
Zone 2: intermediate zone
Zone 3: pericentral vein: centirilobar zone, affected first by ischemia, contains p-450 enzyme, most sensitive to metabolic toxins, site of alcoholic hepatitis
Femoral triangle and lymph
Lateral to Medial you have
Nerve-Artery-Vein-Empty space-Lymphatics (all femoral)
“you have to go lateral to medial to find your NAVEL”
Femoral sheath contains what
Fascial tube 3 to 4 cm below inguinal triangle
contains femoral vein, artery, and canal (deep inguinal lymph nodes) but not the femoral nerve
H2 blockers: names
Cimetidine, Ranitidine, Famotidine, nizatidine
H2 blockers: mechanism
Reversible block of histamine H2-receptors which decrease H+ secretion by parietal cells
Must take before you eat
H2 blockers: Clinical Use of it
Peptic ulcer, gastritis, mild esophageal reflux
H2 blockers: toxicity
cimetidine is a potent inhibitor of cytochrome p450; also has antiandrogenic effects (prolactin release, gynecomastia, impotence, decreased libido in males); can cross blood-brain barrier (confusion, dizziness, headaches) and placenta.
Both cimetidine and ranitidine decrease renal excretion of creatinine
Other H2 blockers don’t have these effects
Proton pump inhibitors: names
omeprazole, lansoprazole, esomeprazole, pantoprazole, dexlansoprazole
Proton pump inhibitors: mechanism
irreversibly inhibit H+/K+ ATPase in stomach parietal cells
must take before meal, only work against active pumps not inactive pumps
Proton pump inhibitors: clinical use
Peptic ulcer, gastritis, esophageal reflux, Zollinger-Ellison syndrome
Proton pump inhibitors: toxicity
increased risk of C Diff infection, pneumonia (get klebsiella infections in the lungs more often), Hip fractures, decreased serum Mg2+ with long term use
Bismuth, Sucralfate: mechanism, clinical use
Bind to ulcer base, providing physical protection and allowing HCO3- secretion to reestablish pH gradient in the mucous layer
used for increasing ulcer healing, travelers’ diarrhea
Misoprostol
A PGE1 analog. increases production and secretion of gastric mucous barrier, decreases acid production
Used to prevent NSAID induced peptic ulcers; maintenance of a PDA; also used to induce labor (ripens cervix)
Causes diarrhea, contraindicated in women of childbearing potential (abortifacient)
Octreotide
Mechanism: long acting somatostatin analog
Uses: acute variceal bleeds, acromegaly, VIPoma, and carcinoid tumors
Toxicity: nausea, cramps, steatorrhea
Antacid use
can affect absorption, bioavailability, or urinary excretion of other drugs by altering gastric and urinary pH or by delaying gastric emptying
all can cause hypokalemia
aluminum hydroxide
antacid
causes constipation, hypophosphatemia; proximal muscle weakness, osteodystrophy, seizures
slow onset and no systemic absorption
Calcium carbonate
antacid
causes hypercalcemia and rebound acid secretion
Systemically absorbed, Rapid onset of action, Long duration, Belching (CO2), gastric distension, Mild systemic alkalosis.
Hypercalcemia in pts w/ impaired renal function if taken with dairy products (milk-alkali syndrome)
Magnesium hydroxide
antacid
Osmotic diarrhea, Renal insufficiency causing hypermagnesemia causing CNS and cardio toxicity
give this with aluminum hydroxide (Causes constipation) and boom! less poopy side effects
Diaphragmatic hernia
abdominal structures enter the thorax; may occur in infants as a result of defective development of peuroperitoneal membrane
most commonly a a hiatal hernia, in which stomach herniates upward through the esophageal hiatus of the diaphragm
sliding hiatal hernia
is most common diaphragmatic hernia
gastroesophageal junction is displaced upward; hourglass stomach
Paraesophageal hernia
gastroesophageal junction is normal and fundis protrudes into the thorax
indirect inguinal hernia
goes through the internal (Deep) inguinal ring, external (superficial) inguinal ring, and into the scrotum. enters internal inguinal ring lateral to inferior epigastric artery. Occurs in infants owing to failure of processus vaginalis to close (can form hydrocele). much more common in males
(follows path of descent of the tests, covered by all 3 layers of spermatic fascia)
Direct inguinal hernia
Protrudes through the inguinal (Hesselbach) triangle. Bulges directly through abdominal wall medial to inferior epigastric artery. Goes through the external (superficial) inguinal ring only. Covered by external spermatic fascia. Usually older men
MDs don’t LIe: Medial to inferior epigastric artery=Direct hernia; Lateral to inferior epigastric artery= Indirect hernia
Femoral hernia
protrudes below inguinal ligament through femoral canal below and lateral to pubic tubercle. more common in females
leading cause of bowel incarceration
Hesselbach triangle
made from the: inferior epigastric vessels, lateral border of rectus abdominis, inguinal ligament
Cholecystokinin
from I cells in Duodenum, Jejunum
increases: pancreatic secretions, gall bladder contraction, relaxation of sphincter of Oddi
decreases: gastic emptying
Regulation: increased release by fatty acids, amino acids
CCK acts on neural muscarinic pathways to cause pancreatic secretion
Gastrin
released from G cells of antrum of stomach and G cells in duodenum. stimulated by increased stomach distention, alkalinization, amino acids, peptides, vagal stimulation; decreased release if pH
Glucose-dependent insulinotropic peptide (AKA GIP)
Released by K cells in duodenum and jejunum in response to fatty acids, amino acids, oral glucose
Exocrine function: decrease H+ secretion
Endocrine function: increase insulin release
AKA: gastric inhibitory peptide
An oral glucose load is used more rapidly than the equivalent given by IV due to GIP release
Motilin
released from small intestine, produces migrating motor complexes during fasting state
Motilin receptor agonists (e.g. erythromycin) are used to stimulate intestinal peristalsis (also why a lot of antibiotics cause diarrhea)
Secretin
release from S cells in duodenum in response to acid or fatty acids in lumen of the duodenum
acts to: increase pancreatic HCO3- secretion, increase secretion, decrease gastric acid secretion
HCO3- neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function
Somatostatin
released from D cells in pancreatic islets and GI mucosa in response to acid and inhibited by vagal stimulation
Acts to :decrease gastric acid and pepsinogen secretion, decrease pancreatic and small intestine fluid secretion, decrease gallbladder contraction, decrease insulin and glucagon release
Somatostatin is an inhibitory hormone; has antigrowth hormone effects (inhibits digestion, absorption of substances needed for growth)
nitric oxide
causes: increase smooth muscle relaxation including lower esophageal sphincter
Loss of NO secretion in implicated in increase LES tone of achalasia
Vasoactive intestinal polypeptide (VIP)
released from parasympathetic ganglia in sphincters, gallbladder, small intestine in response to distention and vagal stimulation, inhibited by adrenergic input
acts to: increase intestinal water and electrolyte secretion, and increase relaxation of smooth muscle and sphincters
VIPoma:
non alpha, non beta islet cell pancreatic tumor that secretes VIP
Copious Watery Diarrhea, Hypokalemia, and Achlorhydria
WDHA syndrome
Intrinsic Factor
released from parietal cells of the stomach
acts to bind Vitamin B12 which is required for the uptake of B12 in the terminal ileum
Autoimmune destruction of parietal cells leads to chronic gastritis and pernicious anemia
Gastric acid
From the parietal cells of the stomach
released in response to histamine ACh and gastrin
decreased release by stimulation from somatostatin, GIP, prostaglandin, and secretin
Acts to decrease stomach pH
Gastrinoma
gastrin secreting timor that causes high levels of acid secretion and ulcers refractory to medical therapy
Zollinger-Ellison syndrome.
Diagnose by seeing mass on CT, giving patient secretin and their gastrin levels go up.
Pepsin
released from chief cells of the stomach
aids in protein digestion
released in response to vagal stimulation and local acid
released as inactive pepsinogen which is cleaved by acid or pepsin to become pepsin
HCO3- (bicarb) in the GI tract
released from the mucosal cells (stomach, duodenum, salivary glands, pancreas) and the Brunner glands (duodenum)
Neutralizes acids
increased secretion in response to pancreatic and biliary secretion with secretin
HCO3- is trapped in mucus that covers the gastric epithelium
Gastrin increases acid secretion primarily by
ints effects on enterochromaffin-like cells (ECL cells) leading to histamine release which acts on the parietal cells. Gastrin can act on parietal cells, but does not have as much effect
Brunner glands
Located in duodenal submucosa
Secrete alkaline mucus
Hypertrophy seen in peptic ulcer disease
Pancreatic secretions
Isotonic fluid; low flow is high in Cl-, high flow is high in HCO3-
alpha-amylase
pancreatic secretion
works in starch digestion
secreted in active form
Lipase, phospholipase A, Colipase
pancreatic secretion
works in fat digestion
Pancreatic secretion: Proteases
works in protein digestion
Includes trypsin, chymotrypsin, elastase, carboxypeptidases
secreted as proenzymes (zymogens)
Trypsinogen
pancreatic secretion
converted to active form of trypsin
trypsin molecules can convert trypsinogen into active trypsin
also converted into trypsin by enterokinase/enteropeptidase, a brush-border enzyme on the duodenal and jejunal mucosa
Carbohydrate absoprtion
only monosaccharides (glucose, galactose, fructose) are absorbed by enterocytes.
Glucose and galactose are taken up by SGLT1 (Na dependent)
Fructose is taken up by facilitated diffusion by GLUT-5
All are transported into the blood by GLUT-2
D-xylose absorption test: distinguishes GI mucosal damage from other causes of malabsoprtion
Iron absorption
only absorbed as Fe2+ in duodenum
Folate absorption
absorbed in jejunum and ileum
B12 absorption
absorbed in terminal ileum along with bile acids, requires intrinsic factor from parietal cells
Peyer patches
Unencapsulated lymphoid tissue found in lamina propria and submucosa of ileum. Contains specialized M cells that sample and present antigens to immune cells
B cells stimulated in germinal centers of peyer patches differentiate into IgA-secreting plasma cells, which ultimately reside in lamina propria
IgA receives protective secretory component and is then transported across the epithelium to the gut to deal with intraluminal antigen
Bile
Composed of bile salts (bile acids conjugated to glycine or taurine, making them water soluable), phospholipids, cholesterol, bilirubin, water, and ions
Cholesterol 7alpha-hydroxylase catalyzes rate-limiting step of bile synthesis
Functions: digestion and absorption of lipids and fat soluble vitamins (ADEK), Cholesterol excretion (only way humans can get rid of cholesterol), antimicrobial activity (via membrane disruption)
Bilirubin
Product of heme metabolism
Removed from blood by liver, conjugated with glucuronate and excreted in bile
direct bilirubin: conjugated with glucuronic acid and is water soluble
Indirect bilirubin: unconjugated; water insoluble
Stercobilin
Bilirubin is excreted with bile and via the gut bacteria turned into urobilinogen and then into stercobilin and excreted in feces. gives poop its brown color
80% of bilirubin in gut is excreted this way, 20% reabsorbed and either peed out or comes back into GI to try again.
Pleomorphic adenoma
benign mixed tumor
Most common salivary gland tumor
Presents as a painless, mobile mass
Composed of chondromyxoid stroma and epithelium
Recurs if incompletely excised or ruptured intraoperatively
Warthin tumor
papillary cystadenoma lymphomatosum
Is a benign cystic tumor with germinal centers
Salivary tumors in general
Generally benign and almost always in the parotid gland
Mucoepidermoid carcinoma
most common salivary malignant tumor and has mucinous and squamous components
Typically presents as a painless, slow-growing mass
Achalasia
Failure of relaxation of LES due to loss of myenteric (auerbach) plexus
High LES opening pressure and uncoordinated peristalsis leads to progressive dysphagia to solids AND liquids (obstruction would by just solids).
Barium swallow shows dilated esophagus with an area of distal stenosis (bird’s beak)
Associated with an increased risk of esophageal squamous cell carcinoma
secondary achalasia can be caused by Chagas disease
Boerhaave syndrome
Transmural usually distal esophageal rupture due to violent retching; surgical emergency