GI: 340 - 342 Flashcards
What are the three sites for anastomoses between the portal circulation and the systemic circulation?
- Esophagus
- Umbilicus
- Rectum
What are the two vessels that anastomose at the esophagus (for portal-systemic)?
Left gastric (portal) and esophageal (systemic)
What are the two vessels that anastomose at the umbilicus (for portal-systemic)?
Paraumbilical (portal) and small epigastric veins of the anterior abdominal wall (systemic)
What are the two vessels that anastomose at the rectum (for portal-systemic)?
Superior rectal (portal) and middle/inferior rectal (systemic)
What are the clinical signs for portal hypertension?
Mnemonic: Gut, butt, and caput (medusae in the umbilicus)
- Esophageal varices
- Caput medusae
- Anorectal varices (NOT internal hemorrhoids)
How can we treat portal hypertension?
Transjugular intrahepatic portosystemic shunt (TIPS) between the portal vein and hepatic vein percutaneously relieves portal hypertension by shunting blood to the systemic circulation
What is the pectinate line?
Formed where the endoderm (hindgut) meets the ectoderm
What is another name for the pectinate line?
Dentate
Where do internal vs. external hemorrhoids occur?
Internal hemorrhoids - above the pectinate line
External hemorrhoids - below the pectinate line
Contrast the more likely cancers above vs. below the pectinate line.
Above - adenocarcinoma
Below - squamous cell carcinoma
What is the arterial supply above the pectinate line?
Superior rectal artery (branch of the IMA)
What is the venous drainage above the pectinate line?
Superior rectal vein –> inferior mesenteric vein –> portal system
What is the lymphatic drainage above the pectinate line?
Deep nodes
Are internal or external hemorrhoids more painful? Why?
Internal hemorrhoids - visceral innervation, NOT painful
External hemorrhoids - somatic innervation (inferior rectal branch of pudendal), painful
Do anal fissures occur above or below the pectinate line?
Below
What is the arterial supply below the pectinate line?
Inferior rectal artery (branch of internal pudendal artery)
What is the venous drainage below the pectinate line?
Inferior rectal vein –> internal pudendal vein –> internal iliac vein –> IVC
What is the lymphatic drainage below the pectinate line?
Superficial inguinal nodes
What is an anal fissure?
Tear in the anal mucosa below the pectinate line
Are anal fissures painful or painless?
Painful on defecation, bloody
Why do anal fissures tend to be posterior?
Area is poorly perfused
What are the three zones of the liver?
Zone I: periportal zone
Zone II: intermediate zone
Zone III: pericentral vein (centrilobular) zone
Does the apical or basolateral side of hepatocytes face the bile canaliculi?
Apical
What does the basolateral side of hepatocytes face?
Sinusoids
Which zone of the liver is affected 1st by viral hepatitis?
Zone I
Which zone of the liver is affected 1st by ischemia?
Zone III
Which zone of the liver is associated with ingested toxins (e.g. cocaine)?
Zone I
What important system does zone III of the liver contain?
Cytochrome P450
What is zone III of the liver particularly sensitive to?
Metabolic toxins
Where is the site of alcoholic hepatitis?
Zone III
What comes together to form the common bile duct?
Common hepatic duct (composed of a right and left hepatic duct) and the cystic duct
Where does the cystic duct originate?
Gall bladder
What is the name of the opening where the common bile duct and the pancreatic duct meet?
Ampulla of Vater
Tumors arising where in the pancreas can cause obstruction of the common bile duct?
Head of the pancreas (near the duodenum)
What sphincter muscle is located at the base of the biliary tree and controls the bile/pancreatic enzymes that reach the duodenum?
Sphincter of Oddi
How is the femoral region organized (lateral to medial)?
Mnemonic: NAVEL Nerve Artery Vein Empty space Lymphatics
What is contained within the femoral triangle?
Femoral vein, artery, nerve
What is the femoral sheath?
Fasical tube 3-4 cm below the inguinal ligament that contains the femoral vein, artery, and canal (deep inguinal lymph nodes)
What structure is notably NOT contained in the femoral sheath?
Femoral nerve
