Peripatetic Final

Question 1

How does an Ileal (Meckel’s) Diverticulum develop?

Answer 1

A Meckel’s diverticulum is a pouch on the wall of the lower part of the intestine that is present at birth (congenital). The diverticulum may contain tissue similar to that of the stomach or pancreas.

• Occasionally a remnant of the yolk stalk fails to regress (2-4% of the population)
• Usually occurs in the terminal ileum
• May become obstructed
• May become infected (diverticulitis)
• May be lined with heteropic mucosa, often gastric (or even pancreatic)
  
  • Acid secreted by heterotopic gastric mucosa may result in ulceration and bleeding

Question 2

What GI related organs are considered retroperitoneal (secondary)?

Answer 2

Duodenum (3/4)

Pancreas

Ascending and Descending Colon (posterior walls)

Question 3

What structures develop from the embryonic dorsal (posterior) mesentery?

Answer 3

Greater omentum

Mesentery proper

Mesocolon

Question 4

What structures develop from the embryonic ventral (anterior) mesentery?

Answer 4

Falciform ligament of the liver

Lesser omentum

Lesser sac

Question 5

What is a nonrotation of the gut?

Answer 5

Nonrotation: the midgut loop fails to rotate as it re-enters the abdomen, results in location of the entire large intestine on the left side of the body

Question 6

What is a mixed rotation of the gut?

Answer 6

Mixed rotation: the midgut loop rotates only partially as it re-enters the abdomen, results in location of the cecum inferior to the pylorus and duodenal obstruction

Question 7

What is a reversed rotation?

Answer 7

Reversed rotation: the midgut loop rotates clockwise instead of counterclockwise

Question 8

What structures are included in the foregut?

Answer 8

Foregut: oral cavity and pharynx, tongue and associated glands, esophagus and stomach, proximal dudoenum, liver, biliary apparatus, pancreas

• The foregut ‘ends’ at the ampulla of vater

Question 9

What structures are included in the midgut?

Answer 9

Midgut: duodenum distal to the ampulla of vater, small intestine, cecum and vermiform appendix, ascending colon and proximaly half to two thirds of the transverse colon

Question 10

What structures are included in the hindgut?

Answer 10

Hindgut: distal third to half of the transverse colon, descending colon and sigmoid colon, rectum

Question 11

What is Hirschprung Disease?

Answer 11

Hirschprung Disease

• Also known as congenital megacolon
• Part of the colon is enlarged as a result of the absence of autonomic ganglion cells in a distal part, in which peristalsis fails to occur
  
  • Multigenic etiology
  • Caused by abnormal migration of neural crest cells
  • Four times as common in males
  • Treated by surgical removal of affected colon

Question 12

What does the Autonomic Nervous System stimulate and receive stimulus from? How is it divided?

Answer 12

ANS

• Stimulates: involuntary muscle, conducting tissues of the heart, glands
• Receives stimulus from: visceral afferent fibers that accompany motor fibers from both divisions
• Divided into sympathetic and parasympathetic divisions
  
  • Different anatomical locations
  • Different neurotransmitters