Small Intestine Flashcards
Which is longer, small bowel or colon?
small bowel 7 meters
colon 1.5 meters
Name 4 things that contribute to large surface area of small bowel
- length
- folds (plicae circulares)
- villi
- microvilli
What is a normal villous to crypt ratio?
3 or 5: 1 (crypts are mitotically active and replenish the cells lining the villi as they are lost)
As you progress thru the small intestine, absorptive cells decrease in number distally, what do goblet cells do?
increase in number distally
Name 4 symptoms of intestinal obstruction
Abdominal pain
Nausea/vomiting
Diarrhea or Constipation
Abdominal distension
T/F- intestinal obstruction most often involves the small bowel and most commonly results from herniation, volvulus, intusception, and adhesions
true
Herniation results from a weakness or defect in the wall of the pertitoneal cavity (inguinal/femoral canals, umbilicus, surgical scar sites) what happens to small bowel loops when they pass thru these areas?
Small bowel loops (typically) become entrapped
- Incarceration: permanent entrapment
- Strangulation: arterial and venous compromise that can result in infarction
What is a volvulus?
Loop of bowel that twists about itself, leads to obstruction and infarction of bowel
Intussusception is when a segment of the intestine telescopes into itself, what is the significance of this in older children and adults?
often associated with an intraluminal tumor that serves as the leading point of traction
Review the rule of 2’s for Meckels diverticulum
- 2% of the population
- Usually within 2 feet (85 cm) of the ileocecal valve
- ~2 inches long
- 2X as common in males
- Most often symptomatic by age 2
What is Meckel’s diverticulum?
failed involution of the vitelline duct (connects the lumen of the developing gut to the yolk sac).
Is Meckel’s diverticulum a true or false diverticulum?
True
Name 3 complications of Meckel’s diverticulum
- Bleeding
- Peptic ulcer due to ectopic gastric epithelium - Obstruction
- Intussusception - Tumor (rare)
- carcinoid
What is a true diverticulum (Meckel’s)
blind outpouching of the ileum that has all three layers of the bowel wall (mucosa, submucosa, and muscularis propria)
T/F- Meckel diverticulum may contain ectopic pancreatic or gastric tissue and gastric parietal cells may result in peptic ulceration of small intestinal mucosa
true
What is the hallmark of malabsorption?
Steatorrhea
A patient presents with anemia, chronic diarrhea, bloating, muscle wasting. His physician informs him that he has a small risk of developing enteropathy associated T cell lymphoma and small intestinal adenocarcinoma. What does he have?
celiac disease
What are the most sensitive serological tests for celiac disease?
- IgA (or IgG) to tissue transglutaminase (TTG)
- IgA (or IgG) antibodies to deamidated gliadin
Most specific but less sensitive serology for celiac?
anti-endomysial antibodies
A patient with celiac is negative for serologies tested. Why?
If negative serologies, remember IgA deficiency, which is more common in celiac patients=>Can get titers of IgG to TTG and deamidated gliadin
What HLA’s are useful in ruling out celiac?
HLA-DQ2 or HLA-DQ8
Why are the duodenum and proximal jejunum most affected by celiac disease?
exposed to highest concentration of gluten from diet
Name key histologic findings in celiac disease
- 1st - increased intraepithelial lymphocytes (CD8+ T cells)
- later - crypt hyperplasia, and villous atrophy
- Loss of mucosal and brush-border surface area → malabsorption
T/F- giardiasis is common in contaminated water in the midwest and can spread person to person in daycare centers
true
Whipples disease is caused by what organism?
Trophyrema whippleii
Review symptoms associated with Whipples disease
Gastrointestinal -Diarrhea, weight loss, and malabsorption Extraintestinal (can exist formonths or years before malabsorption) -Arthritis/arthralgia -Fever -Lymphadenopathy -Neurologic -Cardiac -Pulmonary disease
What other organism mimics Whipple’s disease histologically?
Cannot tell if it is whipple’s or mycobacterium avium intracellulare without AFB stain!
Are malignancies common or uncommon in the small intestine?
uncommon despite the large surface area
Where are the most aggressive neuroendocrine tumors of the small bowel found?
jejunum/ileum
A pale yellow tumor of the ileum is found. It “knuckles” due to fibrosis. What is it?
ileal neuroendocrine tumor
Name 2 vasoactive peptides released in carcinoid syndrome
serotonin
bradykinin
If a carcinoid tumor is able to bypass the metabolic effects of hepatocytes, what symptoms would a person have?
flushing, wheezing, diarrhea
A patient has duodenal lymphoma, what should you check for next?
celiac disease
Acute appendicitis is most common in what age groups?
adolescents and young adults
Symptoms of appendicitis?
- Pain starts periumbilically then localizes to the right lower quadrant
- Nausea/vomiting, low-grade fever, and a mildly elevated peripheral white cell count
What is the most common tumor of the appendix?
low grade neuroendocrine tumor (almost always benign)
A mucocele can also occur in the appendix, what can cause this?
-May result from an obstructed appendix containing inspissated mucin
-Can be from a neoplastic process
(When transmural can result in pseudomyxoma peritoneii (abdomen fills with tenacious, semisolid mucin))
