GI embryology and anatomy Flashcards
What does the foregut include? Midgut? Hindgut? Describe midgut development? What are some pathologies that can occur during that development?
foregut=pharynx to duodenum
Midgut: duodenum to proximal 2/3 of transverse colon
Hindgut: distal 1/3 of transverse colon to anal canal above pectinate line
6th week: herniates into umbilical ring
10th week: reenters abdominal cavity and rotates around SMA
malrotation of midgut, omphalocele, intestinal atresia or stenosis, volvulus
What is gastrochisis? Omphalocele? What causes duodenal atresia? Jujunal, ileal, and colonic atresia?
Extrustion of abdominal contents through abdominal folds-not covered by peritoneum
persistenc of henrniation of abdom. contents into umbilical cord-covered by peritoneum (sealed)
What is the most common tracheoesophageal anomaly. Decribe it. What are the symptoms? Waht is found on CXR? Diagnosis? What is the H type like? Pure EA?
EA with distal TEF is most common
Blind pouch in esophagus with a distal connection from trachea to distal esophagus
Drooling, choking, and vomiting with first feeding
cyanosis due to laryngospasm
Air in stomach on CXR
Faillure to pass NG into stomach
Htype: No blind pouch but a distal TEF
EA: No TEF
What is the pathophys of cong. pyloric stenosis? What is the presentation? Gender? What are the results? Treatment?
Hypertrophy of pyloric sphincter leads to obstruction
Palpable olive mass in epigastric region and nonbilious vomiting (2-6 weeks)
Firstborn males
hypokalemic, hypochloremic metabolic alkalosis (vomiting)
Surgical incision
Describe the development of the pancreas. What is annular pancreas? Results? What is pancreatic divisum? Results? Describe the development of the spleen.
Derived from foregut. Ventral pancreatic buds lead to uncinate process and main pancreatic duct. Dorsal leads to body, tail, isthmus, and accessory duct. Both lead to head.
Annular: Ventral pancreatic duct encircles 2nd part of duodenum leading to obstruction/narrowing
divisum: failure of buds to fuse at 8 weeks. Common. Usually asymp. but may cause chronic abdom. pain and pancreatitis
Spleen: mesentery of stomach (mesodermal) but is supplied by celiac artery.
What are the retroperitoneal structures? Generally what do they include? Specifically? What happens if they’re injured?
GI structures that lack mesentery and non gi structures
Blood or gas in RP space if injured
SAD PUCKER
Suprarenal Aorta Duodenum (2-4) Pancreas (except tail) Ureters Colon (ascending and descending) Kidneys Esophagus Rectum (part)
What does the falciform ligament connect? What structures are contained in it? What abou hepatoduodenal ligament? What is the pringle maneuver? What about gastrohepatic? What about gastrocolic? Gastrosplenic? Splenorenal?
FALCIFORM
LIver to abdominal anterior wall
ligamentum teres hepatis (fetal umb. vein)
HEPATODUODENAL
liver to duod
portal triad
Pinched to control bleeding
GASTROHEPATIC
liver to lesser curv. of stomach
gastric arteries
GASTROCOLIC
greater curvature and transverse colon
gastroepiploic
GASTROSPLENIC
greater curv. and spleen
short gastrics, left gastroepiploic
SPLENORENAL
spleen to poster abdominal wall
splenic artery and vein, tail of pancreas
What are the 4 layers of the gut wall? What are included in each one? How are ulcers different than erosions? What is the frequncy of basal electric rhythm in the stomach? duod? ileum? What are some unique histological characteristics of the esoph, stom, duod, jej, ileum, and colon?
Mucosa=epithelium, lamina propria, muscularis mucosa
Submucosa=submucosal nerve plexus (meissner), secretes fluid (glands)
Muscularis externa=myenteric nerve plexus (auerbach), motility, inner circ. and outer long.
Serosa (intraperitoneal)/adventitia (RP)
Ulcers=submucosa, inner or outer musc. layer
Erosions=only mucosa
stomach=3 waves/min
duod=12 waves/min
Ileum: 8-9 waves/min
esoph: nonkeratinized stratified squamous epithelium
stomach: gastric glands
duod: vill and microvilli (crypts of lieberkuhn); brunners glands (secrete HCO3)
jej: plicae circulares (folds) and crypts of lieber
ileum: peyers patches, plicae circulares (proximal), and crypts of lieber. most goblet cells of small int.
Colon: crypts but no villi, abundant goblet cells; haustra, taenia coli
How can GI arteries be differentiated from non GI arteries? What are the branches of the abdominal aorta in order sup to inf.
GI=anterior branches
Non GI=Lateral branching
Left and right inferior phrenic Celiac trunk Left middle suprarenal SMA Left/right renal Testicular/ovarian artery IMA Bifurcation Median sacral artery left/right common iliac External/internal iliac
What structures does the celiac artery provide? At what vert. level does it come off? What parasymp innervation do these structures receive? Same questions for SMA and IMA
CELIAC:T12/L1
Pharynx and lower esophagus to proximal duodenum; liver, gallbladder, pancreas, spleen
vagus
SMA: L1
Distal duod. to prox. 2/3 of transverse colon
Vagus
IMA: L3
Distal 1/3 of transverse to upper portion of rectum
Pelvic
Describe the branches of the celiac trunk in order? What do they supply? Which branches have poor anastomoses? Strong ones?
Left gastric (esophogeal branch) run along less curv. and anastomose with right gastric
splenic artery (short gastric, left gastroepiploic (run along greater curv. and anastomose w/ right gastroepiploic)) runs behind stomach to spleen
Common hepatic artery (gastroduodenal artery (ant. sup. pancreaticoduodenal artery, right gastroepiploic, post. sup. pancreaticoduod. artery), hepatic artery proper (right gastric artery))
Describe the 3 portosystemic shunts including location, clinical sign, and vessels involved. What is TIPS. Describe it.
esophagus: esophageal varices; left gastric to esophageal veins
umbilicus: caput medusae; paraumbilical to small epigastric veins of the anterior abdom wall
rectum: anorectal varices; superior rectal to middle and inferior rectal
TIPS: transjugular intrahepatic portosystemic shunt between portal vein and hepatic vein
Where is the pectinate (dentate) line? What pathologies occur above the line? What is the blood supply? Venous drainage? Lymph drainage? Same questions for below line? What is the difference between internal and external hemorrhoids? Describe an anal fissure?
Endoderm meets ectoderm
ABOVE
internal hemorrh, adenocarcin
superior rectal artery (IMA)
Superior rectal vein (portal)
Internal iliac nodes
BELOW
ext. hemorrh, squamous cell CA, anal fissures
inferior rectal artery (internal pudendal)
inferior rectal vein (int. pudendal to internal iliac to IVC)
superficial inguinal nodes
Int. hemorr: visceral innervation; not painful
ext: somatic innervation: painful if thrombosed
Anal fissure: tear in anal mucosa below the pectinate line
Pain while Pooping; blood on toilet Paper. Located Posteriorly due to Poor Perfusion
Describe the anatomy of the liver. What are zones 1-3? What are some pathologies in each? What are kupffer cells? What is the space of disse? What cells are there? Why are they significant?
Portal vein, hepatic artery, and bile ducts run together.
Sinusoids come off from portal vein. Sinusoids are lined by hepatocytes. The apical surface of hepatocytes faces bile caniculi, the basal faces the sinusoids.
The space between the hepatocytes and the sinusoids is called space of disse. It contains ito cells which store fat but during certain pathologies can become myofibroblasts leading to cirrhosis.
The flow of the bile ductules and the sinusoids is opposite.
The sinusoids drain inito central veins which drain into the hepatic vein.
Kupffer cells are specialized macrophages
Zone I-periportal zone
affected first by viral hep
ingested toxins (cocaine)
zone II-intermediate zone
Yellow fever
Zone III-pericentral vein (centrilobular zone): affected 1st by ischemia cytochrome p450 sytems metabolic toxins alcoholic hep
Describe the biliary tree. What can happen to gallstones that reach the ampulla of vater? What can happen with some tumors that arise in the head of the pancreas?
They can bause cholangitis and pancreatitis
They can only obstruct common bile duct alone and thus only cause painless jaundice
Cystic duct from gallbladder combine with the common hepatic duct (from left and right hepatic ducts) to form the common bile duct which enters the 2nd part of the duod. at the ampulla of vater with the main pancreatic duct. The sphincter of oddi surrounds the common bile duct at the ampulla.
