10.5 Small Bowel Flashcards

1
Q

Congenital failure of duodenum to reanalyze; associated with Down syndrome

A

Duodenal atresis

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2
Q

3 clinical features of duodenal atresia

A
  1. polyhydramnios
  2. distention of stomach and blind loop of duodenum (double bubble sign)
  3. bilious vomiting
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3
Q

Outpouching of all three layers of the bowel wall (true diverticulum)

A

Meckel diverticulum

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4
Q

what causes meckel diverticulum?

A

failure of the vitelline (omphalomesenteric) duct to involute

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5
Q

4 rules of 2s for Meckel

A

2% of pop,
2 inches long,
within 2 ft of ileocecal valve,
can present w/i first 2 years

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6
Q

4 potential presentations of Meckel

A
  1. bleeding
  2. volvulus
  3. intussusception
  4. obstruction
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7
Q

what causes bleeding in meckel?

A

heterotopic gastric mucosa

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8
Q

twisting of bowel along its mesentery; results in obstruction and disruption of blood supply with infarction

A

volvulus

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9
Q

most common location of volvulus in elderly

A

sigmoid colon

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10
Q

most common location of volvulus in young adults

A

cecum

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11
Q

telescoping of proximal segment of bowel forward into distal segment

A

intussusception

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12
Q

in kids, most common cause of intussusception

A

lymphoid hyperplasia (e.g. due to rotavirus)

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13
Q

in kids, most common location of intussusception

A

terminal ileum (–>I in cecum)

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14
Q

in adults, most common cause of intussusception

A

tumor

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15
Q

abdominal pain + bloody diarrhea + decreased bowel sounds

A

small bowel infarction

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16
Q

three causes of small bowel infarction

A
  1. Thrombosis of SMA
  2. Embolism of SMA
  3. Thrombosis of mesenteric vein
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17
Q

decreased function of the lactase enzyme found in the brush border of enterocytes

A

lactose intolerance

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18
Q

normal function of lactase

A

lactose –> glucose + galactase

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19
Q

presents with abdominal dissension and diarrhea upon consumption of milk products; undigested lactose is osmotically active

A

lactose intolerance

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20
Q

Lactose intolerance on LM?

A

totally normal intestinal mucosa

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21
Q

immune-mediated damage of small bowel villi due to gluten exposure; associated with HLA-DQ2 and DQ8

A

Celiac disease

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22
Q

most pathogenic component of gluten

A

gliadin

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23
Q

once absorbed gliadin is deamidated by

A

tissue transglutaminase (tTG)

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24
Q

deamidated gliadin is presented by APCs via

A

MHC class II

25
Q

damage in celiac mediated by

A

helper T cells (CD4+)

26
Q

presentation of celiac in a child

A

abdominal distension, diarrhea, failure to thrive

27
Q

presentation of celiac in an adult

A

chronic diarrhea and bloating, maybe dermatitis herpetiformis

28
Q

what causes dermatitis herpetiformis

A

IgA deposition at the tips of dermal papillae

29
Q

Lab findings in celiac

A

IgA antibodies against endomysium, tTG, or gliadin; also IgG

30
Q

How would you diagnose celiac in someone with IgA deficiency (inc. incidence of this in celiac)?

A

IgG

31
Q

duodenal biospy in celiac

A

flattening of villi + hypertrophy of crypts + inc. intraepithelial lymphocytes

32
Q

where is damage most prominent in celiac?

A

duodenum (jejunum and ileum are less involved)

33
Q

late complications of celiac that present as refractory dz despite good dietary control

A

small bowel carcinoma, T-cell lymphoma

34
Q

damage to small bowel villi due to an unknown organism resulting in malabsoption

A

tropic sprue

35
Q

unlike celiac, tropical sprue has the following characteristics

A
  • tropical regions
  • arises after infectious diarrhea
  • gets better w. antibiotics
  • damage most prominent in jejunum or ileum
36
Q

where is damage most prominent in tropical sprue

A

jejunum and ileum (duodenum less commonly involved)

37
Q

tropical sprue may lead to what deficiencies

A

vitamin B12 or foalate

38
Q

systemic tissue damage characterized by macrophages loaded with Tropheryma whippelii organisms; PAS+

A

Whipple dx

39
Q

where are the partially destroyed organisms in Whipple dz?

A

Macrophage lysosomes (PAS+)

40
Q

common site of involvement in whipple?

A

small bowel lamina propria

41
Q

macrophages compress what in whipple?

A

lacteals

42
Q

macrophage compresses lacteals, so chylomicrons cannot be transferred from enterocytes to

A

lymphatics

43
Q

whipple presents as

A

fat malabsorption and steatorrhea

44
Q

4 whipple sites o/s small bowel

A
  1. synovium of joints (arthritis)
  2. cardiac valves
  3. lymph nodes
  4. CNS
45
Q

AR deficiency of ApoB48 and ApoB100

A

abetalipoproteinemia

46
Q

AR deficiency of ApoB48 and ApoB100 due to mutation in

A

MTP gene

47
Q

abetalipo presents with malabsorption due to

A

defective chylomicron formation (requires B46)

48
Q

abetalipo p/w absent plasma VLDL and LDL b/c

A

requires B100

49
Q

malignant proliferation of neuroendocrine cells anywhere along gut; low-grade malignancy; chromogranin +;

A

carcinoid tumor

50
Q

most common site of carcinoid

A

submucosal polyp-like nodule in small bowel

51
Q

carcinoid may secrete serotonin –> portal circ. –> metabolized by

A

liver MAO into 5HIAA

52
Q

liver MAO metabolizes serotonin to

A

5HIAA

53
Q

what metabolite in the urine indicates carcinoid?

A

5HIAA

54
Q

how could serotonin bypass liver metabolism in carcinoid?

A

met to liver

55
Q

carcinoid met to liver releases serotonin into hepatic vein –>

A

hepato-systemic shunts –> systemic circulation

56
Q

three symptoms of carcinoid

A

bronchospasm + diarrhea + flushing

57
Q

carcinoid symptoms can be triggered by

A

alcohol or emotional stress

58
Q

carcinoid heart disease is characterized by increased collagen where?

A

RIGHT HEART (TIPS)

59
Q

why is carcinoid HD not seen in left heart

A

MAO in lung