Small Intestine

Question 1

Where is the largest number of hormone-producing cells?

Answer 1

Small intestine

• Body’s largest reservoir of hormone producing cells
• respond to luminal stimuli and secrete over 30 peptide hormones which regulate the functions of the intestine

Question 2

Which of the following features is characteristic of the ileum as opposed ti the jejunum?

Answer 2

The presence of Peyer patches

• The entire small intestine contains valvulae conniventes, also known as plicae circularis
• The jejunum has larger vasa recta, a larger diameter, and a less fatty mesentery
• The ileum contains prominent lymphoid follicles called Peyer patches

Question 3

Within the intestine, epithelial cells originate from stem cells, proliferate in the crypts, and migrate up the villus in 2 to 5 days. this process replaces cells that are removed due to apoptosis or exfoliation. This is rapid turnover makes the small intestine susceptible to

Answer 3

Radiation damage

• High cellular turnover rate of enterocytes makes the small intestine susceptible to damage by inhibitors of proliferation such as radiation and cytotoxic chemotherapy

Question 4

A pocket or sock like outpouching on the anti-mesenteric side of the distal ileum, called a meckel diverticulum si caused by

Answer 4

Persistent vitelline duct

The embryonic gut communicates with the yolk sac by mean of the vitelline duct. failure ofthis structure to obliterate by the end of gestation

Question 5

How much fluid normally enters the adult small intestine each day

Answer 5

8L

• 8-9 liters
• 80% absorbed
• 2 L form oral intake
• 1.5 L of slaiva
• 2.5 L of gastric juice
• 1.5 L of bilopancreatic secretions
• 1 L of fluid secreted by small intestine

Question 6

Carbohydrates such a glucose, galactose, and fructose are absorbed through the intestine via __________

Answer 6

Facilitated diffusion via specific transporters such as SGLT1, GLUT2 and GLUT5

• The 3 terminal products of CHO digestion are transported through the enterocyte brush border membrane

Question 7

Enterohepatic citculation

Answer 7

The secretion of bile acids by the liver and their reabsorption in the distal ileum

Question 8

Secretin glucagon family of gut hormones

Answer 8

• Glucose dependent insulinotropuc polypeptide (GIP)
• Glucose like peptide-1 (GLP-1)
• Vasoactive intestinal polypeptide (VIP)
• peptide histidine isoleucine (PHI)
• growth hormone releasing hormone (GHRH)
• Pituitary adenyl cyclase activating peptide (PACAP)

Question 9

A closed loop obstruction os particularly dangerous because

Answer 9

Intraluminal pressure rises high enough to cause ischemial necrosis

• intestinal segment is obstructed both proximally and distally
  
  • volvolus
• venous congestion and arterial obstruction
• Pain out of proportion
• U-shaped or C shaped dilated bowel loop
• Associated with a radial distribution of mesenteric vessels converging toward a torsio point

Question 10

Therapy of a small bowel obstruction usually consist of prompt surgical correction. In patients with no evidence of closed loop obstruction, and in whome there is no fever or leukocytosis or tachycardia, a period of careful observation with nasogastric decompression may be successful in _____

Answer 10

Partial small bowel obstruction

Obstruction in early post operative period

obstruction due to crohn disease

Question 11

Interventions for post operative ileus

Answer 11

Epidural analgesia (with reduced systemic narcotic administration)

avoiding excess itra-and postoperative fluid administration

A mu-opiod receptor antagonist

• Prokinetic agents such as metoclopramide and eythromycin are rarey useful

Question 12

Risk factors for developing Crohn disease

Answer 12

• AShkenazi jewish
• family members with crohn disease
• higher socioeconomic groups
• smokers

Question 13

The priamry defect associated with crohn disease is a mutation of the NOD2 gene on chomosome 16. This gene encodes for a protein product which

Answer 13

Mediates the innate immune response to microbial pathogens

• A variety of defects in immune regulatory mechanisms such as overresponsiveness of mucosal T cells to enteric flora-derived antigens can lead to defective immune tolerance and sustained inflammation

Question 14

in the resection of stenotic area of intestine in a patient with crohn disease, the best approach is

Answer 14

A Resection margin of 2cm from gross disease

• no difference in the recurrence rates between a 2 cm and 12 cm margin

Question 15

The failure of an enterocutaneous fistula to heal on a regimen of total parenteral nutrition and antisecretory therapy may be due to

Answer 15

• Foreign body
• epithelialization of the fistula tract
• downstream obstruction
• radiation enteritis
• associated infection (abscess or sepsis)
• malignancy
• short fistula tract (<2cm)

Question 16

Most common primary malignancy of the small intestine

Answer 16

Adenocarcinoma of the duodenum

• 35 to 50%
• lymphoma and GIST are the least common (10 to 15%)

Question 17

Adenocarcinoma of the duodenum is associated with what hereditatry oncologic syndrome?

Answer 17

Familial adenomatous polyposis

After resolution of the colonic disease by total colectomy, patients with FAP must be followed with periodic upper GI endoscopy to maintain surveillance for duodenal tumors

Question 18

GIST

Answer 18

• most commonly occure in the stomach (70%)
• frequently presents as GI hemorrhage
• Refractory to conventional cytotoxic chemotherapy
• usually not metastaic on initial diagnosis
• segmental resection of the involved portion is usually sufficient surgical treatment

Question 19

Methods to precent radition enteritis of the small bowel during pelcive irradiation for gynecologic malignancy or rectal malignancy

Answer 19

• tilt table positioning in trendelenburg position during radiation therapy treatments
• closure (reapproximation) of the pelvic peritoneum after priamry resection
• Placement of an absorbable mesh sling to suspend small intestine out of the pelvis during post operative radiation therapy

Question 20

What ectopic tissue is commonly found in a meckel diverticulum

Answer 20

• gastric mucosa (60%))
• pancreatic acini > pancreatic islets > endometriosis > hepatobiliaty tissues

Question 21

A patient with recent onset of ascites after an episode of acute pancreatitis undergoes paracentesis, which reveals cloudy white fluid, What therapy is indicated?

Answer 21

TPN and octreotide

• Chylous ascites can develop as a complciation of operative procedures or inflammatory conditions

Question 22

SHort bowel syndrome has been arbitrarily defined in adults as having small intestine of less than

Answer 22

200 cm

• Functional definition, in which insufficient absorptive capacity results in diarrhea, dehydration, and malnutrition is more appropriate

Question 23

Common causes of short bowel syndrome

Answer 23

• Adults
  
  • mesenteric ischemia
  • malignacy
  • crohn
• Pedia
  
  • intetsinal atresia
  • volvulus
  • necrotizing enterolitis

Question 24

After an emergency operation for bowel infarction in which more than half of the small intestine was removed and a jejunostomy created, high volume ostomy losses cause recurrent dehydration, MAnagement of this condition includes?

Answer 24

• Proton pump inhibitors or H2 receptor antagonists (reduce gastric secretions)
• Octreotide (reduce gastoenteropancreatic secretions)
• loperamide or diphenoxylate (inhibiting motility)