GI - First Aid Flashcards
A new mother gives birth to triplets. One child has a TE fistula. The second has omphalocele. The third has an a ganglionic descending colon. What anatomical sections of the GI tract are affected in each child?
TE fistula is in the foregut (pharynx -> duodenum). Omphalocele is in the midgut (duodenum -> transverse colon). Descending colon is n the hindgut (distal transverse colon -> rectum).
A new mother of a Down Syndrome child is very concerned 3 days after birth when the child still has not had a bowel movement. The child also throws up after feeding. What developmental abnormality associated with trisomy 21 may this child have?
Duodenal atresia caused by failure to recanalize during development.
A pregnant mother goes to the doctor because she feels like there is a lot more fluid in her belly lately. Ultrasonography reveals bowel that has an “apple peel” spiral appearance. What likely caused this?
Occlusion of the SMA during fetal development can cause jejunal, ileal and colonic atresia.
What other birth defect can happen instead of the condition shown below?
Failure of the lateral folds to close during development can result in gastroschisis (intestine not covered by peritoneum) or omphalocele (persistent herniation of intestines through umbilical cord covered by peritoneum) as shown in the image.
When during fetal development is your child at risk for developing omphalocele and when does the risk go away?
6th week: midgut herniates through umbilical ring. 10th week: midgut returns to abdominal cavity with rotation around SMA.
A mother gives birth to a 7 lb baby girl. During her first feeding, the baby chokes and vomits the breast milk. Chest x-ray reveals air in the child’s stomach. The next day the child becomes cyanotic. What are the different causes of this baby’s condition?
This child has esophageal atresia with distal tracheoesophageal fistula, the most common form. Kids can also present with pure esophageal atresia and H-type pure TEF.
A first-time mother brings in her 2 week old boy complaining of vomiting right after feeding. She says the vomit is the same color as the breast milk. Physical exam reveals a palpable olive mass in the epigastric region. What is causing this child’s condition and how do you fix him?
Pyloric stenosis from hypertrophy of the pylorus. This is treated by surgical myotomy.
What embryological origin do pancreatic carcinomas in the head of the pancreas have?
The ventral pancreatic bud contributes to the main pancreatic head and duct. It also forms the entire uncinate process. The dorsal pancreatic bud becomes everything else.
A pregnant woman presents with excess amniotic fluid in her final weeks. The child is born and has bilious vomiting immediately after feeding. How could the child’s pancreas be causing this?
Annular pancreas. The head of the pancreas wraps around the duodenum, causing fetal polyhydramnios and bilious vomiting in the newborn.
A 15 year old girl presents with periumbilical boaring abdominal pain, nausea and vomiting. This happens to her multiple times each year. What congenital abnormality could be causing her condition?
Pancreas divisum. This is due to failure of the ventral and dorsal pancreatic buds to fuse at 8 weeks, resulting in absence of the main pancreatic duct. Pancreatic enzymes are secretes through the minor duct, get backed up and cause chronic pancreatitis.
Does the pancreas arise from the foregut, midgut or hindgut?
Foregut
What organ arises from mesoderm but is supplied by the foregut artery?
The spleen. It rises from the mesentery and is supplied by there celiac artery.
What are the retroperitoneal structures?
“SAD PUCKER”: Suprarenal gland, Aorta/IVC, Duodenum (2 & 3), Pancreas (not tail), Ureters, Colon (descending & ascending), Kidneys, Esophagus, Rectum
What is the neonatal and postnatal function of the ligamentum teres hepatis?
Neonatal: fetal umbilical vein. Adult: falciform ligament connects liver to abdominal wall
After a car accident the driver has internal bleeding from the liver. He is rushed to the hospital and opened up. What abdominal ligament can you compress to control bleeding?
Hepatoduodenal. This contains the portal triad. Placing your fingers in the omental foramen to compress it is called the Pringle maneuver.
What arteries are likely to be ligated when a surgeon needs to access the lesser sac on the right side?
Gastric arteries. These are contained in the gastrohepatic ligament and separates the greater from the lesser sac on the right.
What ligament contains the gastroepiploic arteries?
Gastrocolic ligament. It connects the greater curvature and the transverse colon.
What arteries may be ligated when a surgeon needs to access the lesser sac on the left side?
Short gastrics and left gastroepiploic vessels. These are contained in the gastrosplenic ligament, which connects the greater curvature of the stomach to the spleen.
What ligament contains the splenic artery, vein and tail of the pancreas?
Splenorenal ligament.
What is the difference between a GI ulcer and erosion?
Erosions are only in the mucosa. Ulcers can go all the way through to the outer muscular layer
When does the GI tract have serosa vs. adventitia?
Serosa = intraperitoneal. Adventitia = retroperitoneal.
Which layer of the GI tract is responsible for mucosal motility?
Muscularis mucosa
Which layer of the GI tract is responsible for control of secretory activity?
Submucosal plexus
Which layer of the GI tract is responsible for control of GI muscle contraction?
Myenteric plexus
What region of the GI tract has the fastest basal electrical rhythm (slow waves)?
Duodenum: 12 waves/min. Ileum: 8 waves/min. Stomach: 3 waves/min.
What region of the GI tract is this section from?
Esophagus. Note the nonkeratinized stratified squamous epithelium.
What region of the GI tract is this section from?
Stomach. Note the gastric glands and pits.
What region of the GI tract is this section from?
Gastroduodenal junction. Note the gastric glands and pits on the right indicating stomach. Note the villi, submucosal Brunner’s glands and crypts of Lieberkuhn, indicating duodenum.
What region of the GI tract is this section from?
Jejunum. Note the plicae circulares and crypts of Lieberkuhn and absence of Brunner’s glands and Peyer’s patches.
What region of the GI tract is this section from?
Ileum. Note the Peyer’s patches in the lamina propria and submucosa, plicae circulares, crypts of Lieberkuhn, and largest amount of goblet cells in the small intestine.
What region of the GI tract was this section from?
Colon. Note that there are crypts w/o villi and numerous goblet cells.
What is the blood supply and innervation from the stomach to proximal duodenum, to include the liver, gallbladder, spleen and pancreas?
The foregut is supplied by the celiac artery and vagus nerve.
What is the blood supply and innervation from the distal duodenum to the proximal 2/3 of the transverse colon?
The midgut is supplied by the SMA and the vagus nerve.
What is the blood supply and innervation from the distal 1/3 of the transverse colon to the upper portion of the rectum?
The hindgut is supplied by the IMA and pelvic splanchnic nerves.
What is the watershed region of the gut?
Splenic flexure, this is where SMA supply transfers to IMA supply.
What are the branches that come off of the celiac trunk?
Left: splenic artery and left gastric artery. Right: common hepatic (which gives off the right gastric, gastroduodenal and hepatic proper arteries)
A 60 year old man with a history of hepatitis C presents with liver cirrhosis. What veins would you expect to be dilated in this patient as his liver gets more and more cirrhotic?
Varices of the gut, butt and caput are seen with portal hypertension. This is because blood flowing from the left gastric vein backs up in the liver and anastomosis w/systemic esophageal veins = esophageal varices. Blood flowing from the paraumbilical vein backs up and anastomosis w/systemic epigastric veins = Caput Medusa. Blood flowing from the superior rectal vein backs up in the liver and anastomosis w/systemic middle & inferior rectal veins = Hemorrhoids.
A 60 year old man with a history of hepatitis C presents with liver cirrhosis. Physical exam reveals Caput Medusa, esophageal varices and hemorrhoids. What can you do to treat these symptoms of portal hypertension?
TIPS (transjugular intrahepatic portosystemic shunt) links the portal vein with the hepatic vein to shunt extra blood to the systemic circulation.
What type of hemorrhoids present with painless bleeding? Where does the blood come from?
Those above the pectinate line. This area is derived from the endoderm, receives blood supply from the IMA superior rectal branch and drains blood to the portal system via the superior rectal vein.
What type of hemorrhoids present with painful bleeding? Where does the blood come from?
Those below the pectinate line. This are is derived from the ectoderm, receives blood supply from the pudendal artery via the inferior rectal artery and drains blood to the IVC via the rectal vein.
Rectal cancer with painless bleeding
Adenocarcinoma typically occurs above the pectinate line
Rectal cancer with painful bleeding
Squamous cell carcinoma typically occurs below the pectinate line.
Where does lymphatic drainage flow in the liver?
Space of Disse. This is the space between the hepatocyte and the sinusoids.
What is the function of the cell indicated below?
Kupffer cells are the macrophages in the liver, located in the sinusoids.
What region is the apical part of the hepatocyte?
Apical surface faces the bile canaliculi. The basolateral surface faces the sinusoids.
What region of the liver is affected 1st by viral hepatitis?
Zone I: periportal zone
What region of the liver is affected 1st by ischemia and toxic injury (to include alcoholic hepatitis)?
Zone III: pericentral vein zone. This zone is furthest away from fresh blood and nutrients and gets injured 1st.
What region of the liver contains the P-450 system?
Zone III: pericentral vein zone
A patient presents with a boaring periumbilical pain radiating through to the back. What are the two most common causes of this pain?
Pancreatitis is most commonly caused by gallstones blocking the ampulla of Vater and alcohol causing contraction of the sphincter of Oddi around the ampulla of Vater.
What is a hernia?
Typically it is a protrusion of peritoneum through a site of weakness
What type of hernia is seen in newborns and causes pulmonary hypoplasia?
Diaphragmatic hernia. Failure of the pleuroperitoneal membrane to develop allow bowel to go into the thorax.
What is the most common type of hernia?
Sliding hiatal hernia, note the hourglass stomach.
Hernia characterize by protrusion of the fundus into the thorax
Paraesophageal hernia
What type of hernia follows the path of the descent of the testes in infants?
Indirect inguinal hernia. This follows the path of the testes through the deep inguinal ring, lateral to the inferior epigastric artery, through the external inguinal ring and into the scrotum. Note that it will be covered by all 3 layers of spermatic fascia.
What type of hernia usually happens in older men?
Direct inguinal hernia. This bulges through the inguinal triangle medial to the inferior epigastric artery and goes through the external inguinal ring only. Note that this will only be covered by external spermatic fascia.
What type of hernia is more common in women and is the leading cause of bowel incarceration?
Femoral hernia
A 30 year old woman presents with recurrent peptic ulcers in her duodenum. Endoscopy reveals rugal thickening of the stomach and a mass in the duodenum. What is causing her recurrent ulcers?
She has Zollinger-Ellison syndrome, ulcers from a gastrin-secreting tumor in the duodenum. Upregulation of gastrin secretion by G-cells also happens with chronic PPI use.
What is the effect of gastrin secreted by the G-cells in the antrum of the stomach?
Increased H+ secretion, increased growth of gastric mucosa and increased gastric motility.
How are G-cells regulated?
Increased activity: distention, alkalization, AAs (especially Phe & Trp), vagal stimulation. Decreased activity: stomach pH < 1.5
What is the effect of cholecystokinin secreted by the I-cells in the duodenum and jejunum?
Gallbladder contraction, decreased gastric emptying, relaxation of sphincter of Oddi and activation of muscarinic-mediated pancreatic enzyme secretion.
How are I-cells regulated?
Secretion of CCK is increased by fatty acids and amino acids
What is the effect of secretin secreted by the S-cells in the duodenum?
HCO3 secretion to neutralize gastric acid in duodenum & activate pancreatic enzymes, increase bile secretion and decrease gastric acid secretion.
