Gi Anatomy/embryology/physiology

1. During cholesystectomy with laparoscopic procedure you can't observe?

Spleen, Stomach, Gallbladder

Liver, Small intestine, Appendix

Bladder, Uterus, Prostate

*Any structure that is retroperitoneal, like Pancreas(Except tail),IVC,Aorta,Ascending or descending colon(NOT transverse, so transverse part can actually be seen),from 2nd,3rd and 4th parts of duodenum,Kidneys,Esophagus,Rectum,Suprarenal glands.

During a laparoscopic cholecystectomy, the surgeon is unable to visualize structures that are retroperitoneal due to the nature of the procedure. These structures include the pancreas (except the tail), inferior vena cava, aorta, ascending or descending colon (transverse part can be seen), parts of the duodenum, kidneys, esophagus, rectum, and suprarenal glands.

Explanation

During a laparoscopic cholecystectomy, the surgeon is unable to visualize structures that are retroperitoneal due to the nature of the procedure. These structures include the pancreas (except the tail), inferior vena cava, aorta, ascending or descending colon (transverse part can be seen), parts of the duodenum, kidneys, esophagus, rectum, and suprarenal glands.

2. With Portal hypertension, Splanchic vessels dilate and thus central venous pressure decreases...what does splanchic vessels mean?

Vessels supplying the brain and spinal cord

*Basically vessels supplying viscera of the abdomen,Mainly Celiac, SMA, IMA and all their branches, NOT renal veins/arteries.

Vessels supplying the muscles in the arms and legs

Vessels supplying the heart and lungs

Splanchic vessels refer specifically to the vessels supplying the abdominal viscera such as the celiac, superior mesenteric, and inferior mesenteric arteries. They play a crucial role in portal hypertension.

Explanation

Splanchic vessels refer specifically to the vessels supplying the abdominal viscera such as the celiac, superior mesenteric, and inferior mesenteric arteries. They play a crucial role in portal hypertension.

3. Patient presents with jaundice associated with a mass located in the head of the pancreas, placement of stent in which duct could help to relieve his jaundice?

Common bile duct

Spleenic duct

Cystic duct

*MAIN pancreatic duct(derivative of VENTRAL pancreatic bud), which is likely compressed by the mass located in the head of the pancreas(Head is derived from BOTH Ventral and dorsal pancreatic buds)...

The main pancreatic duct is most likely to be compressed by a mass in the head of the pancreas, leading to jaundice. The common bile duct, splenic duct, and cystic duct do not pass through the head of the pancreas and are not typically associated with jaundice in this scenario.

Explanation

The main pancreatic duct is most likely to be compressed by a mass in the head of the pancreas, leading to jaundice. The common bile duct, splenic duct, and cystic duct do not pass through the head of the pancreas and are not typically associated with jaundice in this scenario.

4. Where is the region herniated into the diaphragm in a baby born with Hiatal hernia derived from?

Hindgut

Endoderm

*FOREgut, Hiatal hernia is due to Herniation of proximal part of Stomach herniates trough the diaphragm..Remember that Foregut gives rise to region of GI from Esophagus to the UPPER part of the duodenum(1st and 2nd portions), note that Primary supply of Foregut is derived from CELIAC Artery. ....Pain is referred in the region of EPIGASTRIUM...Hiatal hernia(usually Cardia of stomach protrued trough diaphragmatic hiatus) can compress vagal trunks and lead to HYPOsecretion of gastric acid

Midgut

Hiatal hernia is due to herniation of the proximal part of the stomach through the diaphragm, which is derived from the Foregut. The Foregut gives rise to the region of the gastrointestinal tract from the esophagus to the upper part of the duodenum, with its primary blood supply coming from the celiac artery.

Explanation

Hiatal hernia is due to herniation of the proximal part of the stomach through the diaphragm, which is derived from the Foregut. The Foregut gives rise to the region of the gastrointestinal tract from the esophagus to the upper part of the duodenum, with its primary blood supply coming from the celiac artery.

5. What are the embryologic origins of lamina propria, muscularis mucosae, submucosa, muscularis externa, adventitia/serosa, and the epithelial lining of the mucosa of the primitive gut?

Lamina propria, muscularis mucosae, submucosa, muscularis externa, adventitia/serosa, and the epithelial lining of the mucosa are all derived from ECTOderm.

Lamina propria, muscularis mucosae, submucosa, muscularis externa, adventitia/serosa are derived from ENDOderm, while the epithelial lining of the mucosa is from MESOderm.

Lamina propria, muscularis mucosae, submucosa, muscularis externa, and adventitia/serosa are all derived from MESOderm while Epithelial lining of the mucosa is derived from ENDOderm...

Lamina propria, muscularis mucosae, submucosa, muscularis externa, adventitia/serosa, and the epithelial lining of the mucosa all originate from the same embryonic layer.

During embryonic development, different layers give rise to various structures in the body. It is important to understand the origins of different tissues and layers for a comprehensive understanding of their functions and relationships in the body.

Explanation

During embryonic development, different layers give rise to various structures in the body. It is important to understand the origins of different tissues and layers for a comprehensive understanding of their functions and relationships in the body.

6. Patient with Sudden onset of rebound tenderness and pain in the UMBILICAL region..Embryologic origin/supply of the organ likely involved?

Patient likely has Gallbladder inflammation, Gallbladder is derived from FOREGUT and thus referred pain often involves UMBILICAL region.

Patient likely has Kidney stone, Kidneys are derived from MESODERM and thus referred pain often involves UMBILICAL region.

*Patient likely has Appendicitis, Appendix is derived from MIDGUT and thus referred pain often involves UMBILICAL region.(Remember during 6 th week of development PHYSIOLOGIC midgut herniates trough the umbilical ring)..MIdgut gives rise to region of GI starting from LOWER Duodenum all the way TILL distal 1/3 of the transverse colon(So it gives rise to PROXIMAL 2/3 of the transverse colon), Vessel that supplies Midgut derivatives is SUPERIOR mesenteric artery....They also want you to know that during 10 th week Midgut goes back to the abdominal cavity and this is also the time when these organs acquire "Adult Positions" and this process needs 270 degree COUNTERclockwise rotation around SUPERIOR mesenteric artery....

Patient likely has Liver abscess, Liver is derived from ENDODERM and thus referred pain often involves UMBILICAL region.

7. How can embryology help you determine the blood supply of the rectum located above the pectinate line?

Remember that the region of the rectum above the pectinate line belongs to the foregut, which is supplied by the celiac trunk.

*Just remember that region of Rectum ABOVE pectinate line belongs to HINDgut(extends from DISTAL 1/3 of transverse colon all the way down till Pectinate line, including the region of rectum ABOVE that line), then you got to remember that all organs of Hindgut are supplied by INFEROR mesenteric artery...Note that pain from organs of Hindgut can be referred to the HYPOGASTRIUM...

Remember that the region of the rectum above the pectinate line belongs to the midgut, which is supplied by the superior mesenteric artery.

Remember that the region of the rectum above the pectinate line belongs to the hindgut, which is supplied by the superior mesenteric artery.

Understanding the embryological origins of different parts of the gut can help in determining their blood supply, as different parts are supplied by different arteries based on their developmental history.

Explanation

Understanding the embryological origins of different parts of the gut can help in determining their blood supply, as different parts are supplied by different arteries based on their developmental history.

8. From which embryonic germ layer is the lower respiratory tract derived?

FOREgut...

Ectoderm

Endoderm

Mesoderm

During early embryonic development, the respiratory system originates from the foregut, specifically the respiratory diverticulum. The mesoderm gives rise to muscle, bone, and blood vessels, the endoderm contributes to the lining of organs such as the digestive and respiratory systems, and the ectoderm forms the nervous system and skin.

Explanation

During early embryonic development, the respiratory system originates from the foregut, specifically the respiratory diverticulum. The mesoderm gives rise to muscle, bone, and blood vessels, the endoderm contributes to the lining of organs such as the digestive and respiratory systems, and the ectoderm forms the nervous system and skin.

9. Baby with Trisomy 18 has herniation of Abdominal contents into the Umbilical cord, are these organs likely covered by peritoneum?

Yes, but only if the baby does not have Trisomy 18.

No, the organs are not covered by peritoneum in this case.

Maybe, depending on the severity of the herniation.

*YES, Omphalocele(Herniation of abdominal organs into the umbilical cord covered by Peritoneum) is characteristic for Edwards syndrome(trisomy 18)...rmember Omphalocele is cOvered by peritoneum while Gastroschisis is NOT....HOWEVER both conditions are due to failure of LATERAL Fold CLOSURE...

Omphalocele is specifically associated with Trisomy 18, and the characteristic feature is herniation of abdominal organs covered by peritoneum into the umbilical cord. It is important to differentiate Omphalocele from Gastroschisis, which is not covered by peritoneum.

Explanation

Omphalocele is specifically associated with Trisomy 18, and the characteristic feature is herniation of abdominal organs covered by peritoneum into the umbilical cord. It is important to differentiate Omphalocele from Gastroschisis, which is not covered by peritoneum.

10. Abdominal contents extruded through abdominal wall and are NOT covered by peritoneum. Describe the location of the protrusion relative to the Umbilicus and identify the primary defect.

Failure of Closure of ANTERIOR folds can lead to Omphalocele and Gastroschisis. The primary defect is Failure of ANTERIOR folds to close.

Failure of Closure of MEDIAN folds can lead to Omphalocele and Gastroschisis. The primary defect is Failure of MEDIAN folds to close.

*Failure of Closure of LATERAL folds can lead to Omphalocele and Gastroschisis, our patient like has Gastroschisis because contents are NOT covered by peritoneum/Amnion, Primary defect is Failure of LATERAL folds to close...

Failure of Closure of POSTERIOR folds can lead to Omphalocele and Gastroschisis. The primary defect is Failure of POSTERIOR folds to close.

11. What is the cause of protrusion of the bladder through the abdominal wall?

Herniation of the small intestine

*Failure of CAUDAL folds to close>Bladder exstrophy...

Muscle weakness in the abdominal wall

Genetic predisposition

Bladder exstrophy occurs due to the failure of the CAUDAL folds to close during development, leading to the protrusion of the bladder through the abdominal wall.

Explanation

Bladder exstrophy occurs due to the failure of the CAUDAL folds to close during development, leading to the protrusion of the bladder through the abdominal wall.

12. What is the mechanism behind a baby born with a Hernia protruding from the umbilicus, and what is the likely prognosis?

Inflammation of the Umbilical ring

Complete closure of the Umbilical ring

Excessive closure of the Umbilical ring

*INCOMPLETE closure of Umbilical ring(Umbilical scar fails to form or it is weak), they do ask prognosis about this and MOST likely it will Close on its own...

A baby born with a Hernia protruding from the umbilicus is typically due to incomplete closure of the Umbilical ring, where the Umbilical scar fails to form or is weak. The prognosis for this condition is generally good as it is most likely to close on its own.

Explanation

A baby born with a Hernia protruding from the umbilicus is typically due to incomplete closure of the Umbilical ring, where the Umbilical scar fails to form or is weak. The prognosis for this condition is generally good as it is most likely to close on its own.

13. What is the mechanism of polyhydramnios in utero, what clinical test can be performed, and what is the mechanism of cyanosis with feeding?

Polyhydramnios occurs due to a lack of amniotic fluid in the amniotic sac. A blood test is the clinical test that can be performed. Cyanosis with feeding is a result of a heart defect.

Polyhydramnios is a condition caused by malnutrition in the mother during pregnancy. An ultrasound is the clinical test that can be performed. Cyanosis with feeding is due to a blockage in the baby's esophagus.

*Failure of nasogastric tube into the stomach, could hep you with confirmation of your suspicion, however more than enough data is given for you to realize that patient likely has Tracheoesophageal fistula(Esophageal atresia+DISTAL TEF, basically proximal part of esophagus ends blindly while distal part connects to the Trachea, this type is known as Type C)..To prevent REFLUX-related aspiration-DUE TO LARYNGOSPASM....*Polyhydramnios=Too much amniotic fluid in the amniotic sac, here because baby can't properly drink it, so more of it stays out...

Polyhydramnios is caused by excess production of saliva in the baby. A chest X-ray is the clinical test that can be performed. Cyanosis with feeding is due to a problem with the lungs.

The correct answer provides a detailed explanation of the mechanisms of polyhydramnios, Tracheoesophageal fistula, and cyanosis with feeding. The incorrect answers introduce false information to test knowledge of the topic.

Explanation

The correct answer provides a detailed explanation of the mechanisms of polyhydramnios, Tracheoesophageal fistula, and cyanosis with feeding. The incorrect answers introduce false information to test knowledge of the topic.

14. In a newborn who presents with Billious vomiting, abdominal distension, what does 'Double Bubble' represent? What chromosomal abnormality is likely present? What is the embryologic defect leading to the GI manifestations?

C) Double Bubble sign represents an abnormality in the distal part of the small intestine leading to Meckel's diverticulum, often seen in babies with Marfan Syndrome.

A) Double Bubble sign represents a normal variant in newborns which resolves on its own without any intervention.

B) Double Bubble sign is indicative of pyloric stenosis, commonly associated with Turner Syndrome.

*Double Bubble sign=Basically DILATED Stomach and PROXIMAL part of the duodenum(Both come from foregut)DUODENAL ATRESIA-primarily due to failure in RECANALIZATION process and mechanism for that involves Failure in APOPTOSIS...Duodenal Atresia is associated with Trisomy 21(Down's syndrome)

Duodenal atresia is a well-documented condition associated with the Double Bubble sign, and the link to Trisomy 21 is significant in the context of chromosomal abnormalities in newborns presenting with this sign.

Explanation

Duodenal atresia is a well-documented condition associated with the Double Bubble sign, and the link to Trisomy 21 is significant in the context of chromosomal abnormalities in newborns presenting with this sign.

15. What is the mechanism behind Jejunal, Ileal, and Colonic atresia?

Infection with a specific type of virus during the first trimester of pregnancy

Excessive amniotic fluid intake by the mother during pregnancy

Genetic mutation during fetal development

*VASCULAR accident(Vascular OCCLUSION) during development(in Utero),primarily disruption of MESENTERIC VESSELS>ISCHEMIC NECROSIS(COAGULATIVE)>Apple peel appearance(Check pic) due to segmental resorption..Baby will likely present with Bilious vomiting within first 24 hours...Apple peel sign is usually manifestation of involvement of SUPERIOR mesenteric artery as these patients get BLIND-ending jejunum+Area of absent SMALL bowel and dorsal mesentery and very characteristically TERMINAL Ileum SPIRALED around Ileocolic vessel...THIS IMAGE is NOT labeled for reuse so check it....

16. What is the mechanism of antibiotic associated with hypertrophic pyloric stenosis in infants?

Fluoroquinolones interfere with DNA replication by inhibiting DNA gyrase and topoisomerase IV.

Tetracyclines inhibit protein synthesis by blocking the A site of the ribosome.

*Baby Likely has HYPERTROPHIC Pyloric stenosis(Increase in the MASS not number of cells),Hypertrophic pyloric stenosis is MCC of Gastric outlet obstruction in infants it is More common inf FIRSTBORN MALES(can be tested), and has association with exposure to macrolides(Work by Blocking TRANSLOCATION, trough binding 23S rRNA of 50 S subunit),note however that Macrolides are NOT teratogensHYPOchloremic(key) Metabolic Alkalosis(Low Bicarbonate levels) with HYPOkalemia is characteristic finding...Treat with Pyloromyotomy(Incision involves BOTH circular and longitudinal muscles of pylorus)...in one question i've encountered a case where you had to pick appropriate IMAGING finding in such a patient, basically 1 month old boy presented with NON-bilous projective vomiting and had signs of Down syndrome(Like epicanthal folds,single crease), i was so tempted to pick Double-bouble sign, but right answer was THICKENED pylorus on ultrasound, KEY was the fact that duodenal atresia would present within 24 hours while pylorid stenosis would be more likely at such an age(1 months after birth)...

Aminoglycosides inhibit protein synthesis by binding to the 30S ribosomal subunit.

17. Where do the main pancreatic duct and accessory pancreatic duct have their embryologic origins?

MAIN-Comes from DORSAL bud

Accessory-Comes from VENTRAL bud

Accessory-Comes from DORSAL bud

*MAIN-Comes from VENTRAL bud....

During development, the main pancreatic duct originates from the ventral bud, while the accessory pancreatic duct originates from the dorsal bud.

Explanation

During development, the main pancreatic duct originates from the ventral bud, while the accessory pancreatic duct originates from the dorsal bud.

18. Which structures have embryologic origin of VENTRAL pancreatic bud?

Islets of Langerhans(5) and Acinar cells(6)

Splenic vein(3) and Superior mesenteric vein(4)

*Just remember that UNCINATE process(2) and MAIN pancreatic duct(8) come from VENTRAL pancreatic bud, everything else comes from Dorsal pancreatic bud....BUT the HEAD region(1) has contributions from BOTH( and yes that's important)

Body of pancreas(7) and tail of pancreas(9)

Correct answer specifies the structures originating from the VENTRAL pancreatic bud versus the Dorsal pancreatic bud, as well as the unique case of the HEAD region having contributions from both buds.

Explanation

Correct answer specifies the structures originating from the VENTRAL pancreatic bud versus the Dorsal pancreatic bud, as well as the unique case of the HEAD region having contributions from both buds.

19. What does retroperitoneal structure mean?

Structure in front of the peritoneum, covered by mesentery.

Structure located outside the abdominal cavity, with no peritoneal connection.

Structure within the peritoneal cavity, surrounded by peritoneum.

*Structure BEHIND the peritoneum, now important point here is that they do NOT have Peritoneal covering(Mesentery is basically fold of peritoneum which is NOT present on retropertioneal organs)...

Retroperitoneal structures are positioned behind the peritoneum and do not have peritoneal covering like mesentery, which distinguishes them from structures within the peritoneal cavity or those covered by mesentery.

Explanation

Retroperitoneal structures are positioned behind the peritoneum and do not have peritoneal covering like mesentery, which distinguishes them from structures within the peritoneal cavity or those covered by mesentery.

20. Which part of Esophagus is considered RETROPERITONEAL?Cervical/Thoracic/Abdominal.

Abdominal

*THORACIC portion of Esophagus is considered retroperitoneal..

None of the above

Cervical

The esophagus is divided into three parts: cervical, thoracic, and abdominal. The thoracic portion of the esophagus is considered retroperitoneal, meaning it lies behind the peritoneum in the abdominal cavity.

Explanation

The esophagus is divided into three parts: cervical, thoracic, and abdominal. The thoracic portion of the esophagus is considered retroperitoneal, meaning it lies behind the peritoneum in the abdominal cavity.

21. Which pancreatic bud is NOT retroperitoneal?

*DORSAL bud gives rise to Tail of the pancreas which is NOT a retroperitoneal organ....

MARGINAL bud gives rise to the Body of the pancreas which is retroperitoneal.

ACCESSORY bud gives rise to the Head of the pancreas which is retroperitoneal.

VENTRAL bud gives rise to the Uncinate process of the pancreas which is retroperitoneal.

The dorsal bud of the pancreas gives rise to the tail of the pancreas, which is not retroperitoneal unlike other parts of the pancreas which develop from ventral, accessory, and marginal buds.

Explanation

The dorsal bud of the pancreas gives rise to the tail of the pancreas, which is not retroperitoneal unlike other parts of the pancreas which develop from ventral, accessory, and marginal buds.

22. How can you differentiate between IVC and Aorta on cross-sectional CT images?

The Aorta appears larger in size compared to the IVC on CT images.

*Well IVC is more on the RIGHT side of the vertebrae while Aorta is more on to left side, Also IVC will look larger...

IVC is typically more posterior to the vertebrae, while the Aorta is more anterior.

IVC is located more on the LEFT side of the vertebrae, while the Aorta is more on the right side.

When interpreting cross-sectional CT images, it is essential to understand the relative positioning and size differences between the Inferior Vena Cava (IVC) and the Aorta. The correct answer highlights the key characteristics to look for in order to differentiate between the two structures.

Explanation

When interpreting cross-sectional CT images, it is essential to understand the relative positioning and size differences between the Inferior Vena Cava (IVC) and the Aorta. The correct answer highlights the key characteristics to look for in order to differentiate between the two structures.

23. Which parts of the Rectum are RETROperitoneal?

*UPPER 2/3 of it...

The entire Rectum.

The LOWER 1/3 of it.

The lateral walls of it.

The correct answer is the UPPER 2/3 of the Rectum because they are situated behind the peritoneum, whereas the LOWER 1/3 is intraperitoneal. The entire Rectum is not retroperitoneal, and the lateral walls are not specifically retroperitoneal either.

Explanation

The correct answer is the UPPER 2/3 of the Rectum because they are situated behind the peritoneum, whereas the LOWER 1/3 is intraperitoneal. The entire Rectum is not retroperitoneal, and the lateral walls are not specifically retroperitoneal either.

24. Which parts of the colon are RETROPERITONEAL?

*ASCENDING part(Supplied by SMA) and DESCENDING part(Supplied by IMA)

Cecum (Supplied by ileocolic artery)

Sigmoid part (Supplied by sigmoid arteries)

Transverse part (Supplied by middle colic artery)

The ascending and descending parts of the colon are considered retroperitoneal because they are located behind the peritoneum. The blood supply to the ascending part comes from the superior mesenteric artery (SMA), while the descending part is supplied by the inferior mesenteric artery (IMA). The transverse part is intraperitoneal as it is suspended by the transverse mesocolon. The sigmoid part receives blood supply from sigmoid arteries and is intraperitoneal, and the cecum is also intraperitoneal and supplied by the ileocolic artery.

Explanation

The ascending and descending parts of the colon are considered retroperitoneal because they are located behind the peritoneum. The blood supply to the ascending part comes from the superior mesenteric artery (SMA), while the descending part is supplied by the inferior mesenteric artery (IMA). The transverse part is intraperitoneal as it is suspended by the transverse mesocolon. The sigmoid part receives blood supply from sigmoid arteries and is intraperitoneal, and the cecum is also intraperitoneal and supplied by the ileocolic artery.

25. FALCIFORM ligament is derivative of? It contains? It connects?

FALCIFORM ligament is derivative of POSTERIOR mesentery and it contains PANCREATIC duct

FALCIFORM ligament is derivative of LATERAL mesentery and it contains HEPATIC artery

FALCIFORM ligament is derivative of DORSAL mesentery and it contains SPLENIC ligament

*FALCIFORM ligament is derivative of VENTRAL mesentery and it contains ROUND LIGAMENT=LIGAMENTUM TERES HEPATIS(Derivative of UMBILICAL VEIN)*Falciform ligament(Derivative of ventral mesentery) Connects Liver to ANTERIOR ABDOMINAL wall..

Falciform ligament is a structure that connects different abdominal components and understanding its origins, contents, and connections is crucial for a comprehensive understanding of abdominal anatomy.

Explanation

Falciform ligament is a structure that connects different abdominal components and understanding its origins, contents, and connections is crucial for a comprehensive understanding of abdominal anatomy.

26. Why might a patient who has undergone Splenectomy present with signs/symptoms of Diabetes?

Due to surgical complications during Splenectomy leading to pancreatic dysfunction.

*Because the TAIL of the Pancreas along with Splenic vessels runs in the SPLENORENAL ligament to reach the HILUM of the spleen..thus with Splenectomy, tail of the pancreas can be mistakenly removed, and as it contains lot's of endocrine cells<Removal>Signs of diabetes...Note however that Splenorenal ligament connects Spleen to POSTERIOR abdominal wall....

Because the immune response following Splenectomy triggers an autoimmune reaction affecting the pancreas.

As a result of increased stress on the remaining pancreatic tissue after Splenectomy.