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GI Week 2 > Lecture 14: Small Bowel and Colon, Non-neoplastic diseases > Flashcards

Lecture 14: Small Bowel and Colon, Non-neoplastic diseases Flashcards

1
Q

What are the steps for fetal development of gut?

A
  1. protrusion through umbilical area
  2. rotation outside abdomen
  3. retraction back into abdomen
  4. active tacking down
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2
Q

What is the structure and function of small bowel?

A
  1. absorption of nutrients
  2. motility
  3. barrier/immune system
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3
Q

What are plical folds?

A

Aka circular folds
Aka valves of Kerckring
Large valvular flaps projecting into the lumen of the bowel
Smaller than the haustra of the colon, used to distinguish small from large intestine

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4
Q

What is the key characteristic of duodenum?

A

Brunner’s glands

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5
Q

What is the key characteristic of ileum?

A

Peyer’s patches

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6
Q

What are the most common embryologic abnormalities?

A
  1. Meckel’s diverticulum
  2. Omphacele
  3. Malrotation
  4. Atresia (associated with trisomy 21)
  5. heterotopias (normal tissue in abnormal locations)
  6. Hirschsprung’s mega colon
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7
Q

What is Meckel’s diverticulum?

A

Diverticula are remnants of the vitelline (omphalomesenteric duct), which connects lumen of gut to the yolk sac
Occurs in the ILEUM
True diverticulum = contains all the layers

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8
Q

How do you cause ischemia?

A
  1. thrombotic/embolic
  2. volvulus, adhesions
  3. vasculitis
  4. hypotension
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9
Q

What is the most sensitive to ischemic injury?

A

Mucosal compartment, specifically the epithlium

Most metabolically active

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10
Q

What are Ladd bands?

A

Bands of fibrosis that occur when you are “tacking down” the wrong areas of the gut (i.e. the areas of the gut that aren’t supposed to be secondarily retroperitoneal)
Ladd bands serve as a fulcrum of twisting and ischemia

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11
Q

What does thumb printing look like?

A

Dark areas = the thumb printing or areas of edema from ischemia

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12
Q

What are types of idiopathic inflammatory bowel disease?

A
  1. Ulcerative colitis
  2. Crohn’s
    Both due to abnormal regulation of the immune system which is reacting to external agent
    Highest in Western country
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13
Q

What are the key characteristics of ulcerative colitis (only affects the colon!!! Because of colitis)?

A

Geographically LIMITED, starts from distal and goes proximal
Affects the mucosa ONLY
Colon only, no skip areas
Risk of carcinoma and primary sclerosing cholangitis
Crypt distortion in microscope

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14
Q

What are the key characteristics of Crohn’s?

A

Geographically INDISCRIMINANT and may injure all layers of the gut
Anywhere from mouth to anus
-can skip areas
Transmural inflammation can lead to FISTULA or strictures
Extra intestinal manifestations
Carcinoma risk in inflamed area

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15
Q

What are the microscopic features of Crohn’s?

A
  1. Granulomas
  2. Fibrosis
  3. Cryptitis/knife ulceration
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16
Q

What is the pathogenesis of Crohn’s disease?

A
  1. NOD2 mutations!
    • leads to abnormal granules in Paneth cells (macrophages)
    • decreased killing of luminal pathogens
    • defective sensing and clearing o intracellular bacteria
    • decreases synthesis of IL10 (anti-inflammatory cytokine) by preventing p38 phosphorylation
17
Q

What is NOD2 mutation associated with?

A

Crohn’s
Lack of immune function
It is the protein within a monocyte that interacts with the lipopolysaccharide (LPS) of a bacteria
If you have a mutation in leucine rich repeats (LRR) of NOD2 protein, then you have decrease immune function

18
Q

What is the Crohn Disease Model?

A
  1. NOD2 mutations lead to malformed paneth cell granuls
  2. genetic predisposition to weak cell-cell junctions
  3. change in gut flora to include adherent invasive E coli (AIEC)
  4. NOD2 and other mutations lead to abnormalities in autophagy, decreasing clearance of bacteria
  5. activation of TNF and cytokines but NO IL-10 to dampen response (IL-10 is anti-inflammatory)
  6. Therefore you get unregulated secretion of TNF, cytokines and thus inflammation
19
Q

What is the significance of “creeping fat”?

A

This is how CD can present grossly

Because “fat” is reflective of transmural inflammation

20
Q

What is the significance of tubular colon?

A

Repaired ulcerative colon

Normal after healing

21
Q

What is the most important feature of ulcerative colitis?

A

Crypt distortion
Chronic mucosal injury
Infections do NOT cause crypt distortion

22
Q

What must one do in order to diagnose idiopathic IBD?

A

Must rule out infectious causes

23
Q

What are the processes that lead to inflammation?

A

Two broad categories

  1. ulcerative colitis
  2. Crohn disease
  3. lymphocytic colitis
  4. Celiac
  5. infection
  6. ischemia, trauma
24
Q

The compartment of the gut that is most sensitive to ischemic damage is?

A

EPITHELIUM (part of the mucosa that is farthest from blood supply)

25
Q

Crypt distortion is most often associated with?

A

CD and UC

GI Week 2 (15 decks)

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