Small and Large Intestine Flashcards Preview

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Flashcards in Small and Large Intestine Deck (82):
1

What histological features distinguish the duodenum? Jejunum? Ileum?

Duodenum - Brunner's glands in the submucosa

Ileum - Peyer's patches

Jejunum - neither

2

What is the function of Brunner's glands?

Secrete mucus and HCO3- to neutralize acid coming into duodenum from stomach

3

What is the function of Peyer's patches?

Large aggregates of lymphoid cells used for host defense

4

What is the function of Paneth cells?

Contain pink granules with lysozymes, defensins, and other things to aid digestion and help regulate microbiota of small intestine

5

Where in the GI tract are ganglion cells located?

Submucosa (Meissner's/submucosal plexus)

Between the inner circular muscle and outer longitudinal muscle of the muscularis propria (Auerbach/myenteric plexus)

6

What is the main difference between gastroschisis and omphalocele?

Gastroschisis has exposure of abdominal contents without the peritoneum

Omphalocele has abdominal contents surrounded by the peritoneum and the amnion of the cord

7

What is intussusception?

Telescoping of one part of bowel into another (often part of small intestine inside large intestine)

Could cause obstruction of blood vessels and of the food bolus moving through intestines

8

What is volvulus?

Twisting of bowel around its mesentery, leading to obstruction and infarction

9

What is necrotizing enterocolitis?

Acute necrotizing inflammation of small and/or large intestines

Edema -> necrosis -> gangrenous bowel

Most common acquired GI emergency in premie or low birth weight neonate

10

Meckel Diverticulum
What is the pathologic issue?

Persistence of the vitelline duct

11

Meckel Diverticulum
Known as disease of 2's because...

2% of population, mostly asymptomatic

2 inches long
Within 2 feet of ileocecal valve in small intestine
2:1 M:F ratio

2 major complications:
Pain with inflammation
Hemorrhage with ulcer

12

Hirschsprung Disease
What is the basic pathologic issue?

Absence of ganglion cells
Death of neural crest cells from cecum to rectum

13

Hirschsprung Disease
How is it diagnosed?

Suction biopsy needed to get a biopsy deep enough to include submucosa and muscularis propria

14

Hirschsprung Disease
What do you expect to see on histology?

Lack of ganglion cells in the myenteric plexus

15

Hirschsprung Disease
Treatment

Resection of the portion of bowel without the neurons

16

What are some general symptoms of malabsorption?

Chronic diarrhea
Weight loss
Abdominal pain
No villi -> steatorrhea

17

What are some signs of pancreatic insufficiency?

Increased neutral fat
Normal D-xylose absorption test (urinary excretion)

18

Disaccharidase Deficiency
What is the most common deficiency?

Lactase deficiency (Lactose intolerance)

19

What happens when a person with lactose intolerance eats lactose?

Due to lack of lactase enzyme, the intestines cannot digest lactose. Lactose remains in intestinal lumen, pulling water into the lumen via osmotic forces and causing an osmotic diarrhea

20

Abetalipoproteinemia
What is the basic issue?

Low synthesis of apolipoprotein B, which is required for chylomicron generation

Results in decreased secretion of cholesterol and fat accumulation in enterocytes

Presents as failure to thrive in early childhood

21

Celiac Disease
What is the basic issue?

Autoimmune disorder resulting in damage to small intestine lining when foods containing gluten are eaten

22

Celiac Disease
Diagnosis

Serum test
Look for IgA/IgG to tissue transglutaminase (tTG), deaminated gliadin, HLA DQ2 or DQ8

Biopsy
Look for increased intraepithelial lymphocytes and flattening of the villi

23

Celiac Disease
Clinical Features in Infants

Diarrhea
Failure to thrive
Abdominal distension
Anorexia
Weight loss
Irritability

24

Celiac Disease
Clinical Features in Older Children and Adults

Abdominal pain
Nausea
Vomiting
Bloating/Constipation

Diarrhea
Flatulence
Weight loss
Anemia
Fatigue

25

Celiac Disease
Describe Dermatitis Herpetiformis

Skin blistering disease caused by IgA deposition in the dermal papillae

Can cause obstruction of blood vessels in dermis, causing epidermis to separate and blister

26

Tropical Sprue
What is it caused by? Where? How to treat?

Similar findings to celiac disease, caused by an unknown infectious agent

Seen in Caribbean

Treat with antibiotics

27

Bacterial Infectious Enterocolitis
What is seen on histology?

Acute inflammation of the colon with many PMNs in the epithelium and lamina propria

28

List two common viral causes of enterocolitis

Noravirus
Rotavirus

29

List the two common protozoan causes of enterocolitis

Giardia - commonly from drinking freshwater streams

Entamoeba Histolytica - causes flash shaped ulcer on histology

30

Pseudomembranous Colitis
What often precedes the development of this disease?

Course of broad spectrum ABX

31

Pseudomembranous Colitis
Gross appearance of colon

Yellow-green false membrane of mucus and PMNs

See mushroom shaped pseudomembrane on histology

32

What organism is associated with Pseudomembranous Colitis?

Clostridium difficile

33

Collagenous Colitis
Who commonly gets this? What is the main symptom?

Middle aged females with watery diarrhea

34

Collagenous Colitis
What is seen histologically?

Lymphocytes in the epithelium

Subepithelial deposition of collagen

35

Lymphocytic Colitis
What is the primary symptom? What is seen histologically?

Chronic watery diarrhea

Intraepithelial lymphocytes are present, but there is no subepithelial collagen

36

Whipple Disease
Describe the basic pathogenesis

Organism: Tropheryma whippleli
Macrophages engulf the organism, distend the villi, congest blood vessels and lymphatics

May cause enterocyte necrosis or poor absorption

37

What are two main types of IBD?

Crohn's Disease
Ulcerative Colitis

38

Crohn's Disease
Symptoms

Diarrhea (non-bloody)
Cramping abdominal pain (RLQ)
Low grade fever

Asymptomatic periods (skip periods) with recurrent attacks or flare ups

39

Crohn's Disease
Complications and extra-intestinal manifestations

Erythema nodosum (subcutaneous nodules on lower extremities)
Pyoderma gangrenosum
Uveitis
Kidney stones

40

Crohn's Disease
Gross appearance

Fissure moving through entire wall into the muscularis propria and serosa

Narrowing of lumen (stricture)

41

Crohn's Disease
Histology

Non caseating granulomas
Transmural inflammation

See many PMNs in the crypt

42

Ulcerative Colitis
Symptoms

Bloody diarrhea
Recurring with asymptomatic intervals

43

Ulcerative Colitis
Complications

Primary sclerosing cholangitis

44

Ulcerative Colitis
Pathogenesis

Inflammation involving only the colon, spreading up from rectum through colon.

Pseudopolyps are seen grossly (normal areas surrounded by ulcerated areas)

45

Ulcerative Colitis
Histology

Crypts filled with PMNs is primary feature

More superficial process than Crohn's -- Ulcerative Colitis only involves the mucosa and submucosa

46

Crohn's vs. Ulcerative Colitis
Which is continuous?

Ulcerative colitis involves rectum and colon continuously

Crohn's has skip areas

47

Crohn's vs. Ulcerative Colitis
Which involves the full thickness of the wall?

Crohn's is transmural

Ulcerative Colitis is only mucosa and submucosa

48

Crohn's vs. Ulcerative Colitis
What are the extraintestinal involvements of each?

Crohn's - migratory polyarthritis and kidney stones

Ulcerative Colitis - Primary sclerosing cholangitis

49

Diverticulum
Where are they most common?

Sigmoid colon

50

Diverticulum
Difference between true and false diverticula

True - involving mucosa, submucosa, and muscularis propria

False- involving mucosa and submucosa only

51

Diverticulum
How does diverticulitis develop?

Diverticulum is a blind outpouching of the colon where fecal matter can get stuck, cause inflammation, thus causing diverticulitis

52

Where are direct hernias found? What about above and below those?

Hasselbach's triangle

Above - indirect
Below- Femoral

53

Ischemic Bowel Disease
Symptoms

Severe abdominal pain
Tenderness
Bloody diarrhea
Melena
Could lead to sepsis, shock, death

54

Ischemic Bowel Disease
What is the watershed zone?

Splenic flexure
Area furthest away from blood supply, so it is at higher risk for ischemia

55

Ischemic Bowel Disease
Pathogenesis

Something causes hypoxic or reperfusion injury to the colon

Athersclerosis, AAA, hypercoagulable state, oral contraceptives, embolization, cardiac failure, shock, dehydration, vasoconstrictive drugs, vasculitis

56

What are Hemorrhoids?

Anal varices
Dilated anal and perianal collateral vessels

Causes pain and some abdominal bleeding

57

What is the difference between internal and external hemorrhoids?

Internal - above pectinate line; receive visceral innervation and are NOT painful

External- below pectinate line; receive somatic innervation and are painful

58

Inflammatory Polyp
What syndrome is it associated with?

Solitary Rectal Ulcer Syndrome

59

Hamatomatous Polyp
What syndrome is it associated with?

Peutz-Jeghers syndrome

60

Peutz-Jeghers Syndrome
What is the inheritance? What are the symptoms?

Autosomal dominant

Hyperpigmented melanotic macules of mouth, lips, genitals, hands

61

Peutz-Jeghers syndrome
What are patients at risk for?

Polyps themselves are not malignant, but there is increased risk of CRC and other malignancies (pancreas, breast, lung, ovary, uterus, testes)

62

Hyperplastic Polyp
What is the appearance on histology?

Proliferation of mature goblet cells

Serrated/sawtooth appearance of goblet cells stacking on one another

63

Adenomatous Polyp
What are the two broad classifications of it's gross appearance? Which is more dangerous?

Pedunculated (on a stalk)

Sessile (growing directly out of intestinal wall)

Sessile is more dangerous

64

Adenomatous Polyp
Tubular vs. Villous appearance - Which is more dangerous?

Villous is more likely to grow into an adenocarcinoma

65

Sessile Serrated Adenoma
Where do they mostly occur?

Adenomatous polyp in the RIGHT colon

Sawlike serrated areas

66

Familial Adenomatous Polyposis
What is the inheritance? How is it treated?

Autosomal dominant
Defect in APC gene on chromosome 5

Treated with prophylactic colectomy for APC mutations

67

Gardner Syndrome
What are the symptoms?

Polyps similar to FAP

Osteomas of mandible, skull

Fibromatosis- non-neoplastic fibroblast proliferation

68

Turcots Syndrome
What are the symptoms?

FAP with CNS tumors
Medulloblastomas
Glioblastomas

69

HNPCC
What is the defect? Inheritance?

Autosomal dominant defect in DNA mismatch repair, leading to increased risk of many cancers

70

Describe the function of the APC gene product. What happens when it is knocked out?

APC binds beta-catenin and prevents it from activating transcription of many tumor promoting genes.

When APC is knocked out (2 hits needed), Beta-catenin is free to activate transcription of MYC, cyclin D1, others to promote tumors

71

DNA mismatch repair defects are seen (mostly) in what disorders?

HNPCC and sessile serrated adenomas

72

APC mutations are seen mostly in what disorders?

FAP or sporadic CRC

73

DNA mismatch repair defects may be caused in mutations in what genes?

MLH1
MSH2
MSH6
PMS1
PMS2

74

Colon Cancer
How will it appear on imaging?

Apple core lesion on barium X ray because tumor is compressing and narrowing lumen

75

Colon Cancer
How are the shapes of R sided and L sided colon cancers different?

R sided - tumor grows on one side of lumen and obstructs (exophytic tumor)

L sided - "Napkin ring" lesion that causes obstructive symptoms much more quickly

76

Which side of the colon has a larger diameter?

Right, so R sided colon tumors take longer to cause obstruction

77

What are the general presenting symptoms of R and L sided colon cancers?

R sided - iron deficiency anemia

L sided - obstruction

78

What types of cancers are likely to be seen in the rectum and anus?

Rectum = adenocarcinoma

Anus = squamous cell carcinoma

79

List the stages of colon cancer progression

T is -- intraepithelial or lamina propria

T1- submucosa
T2- muscularis externa
T3- serosa
T4- peritoneum, other organs, perforation

80

Appendicitis
Symptoms

Nausea/vomting
Periumbilical pain localizing to RLQ
Obstruction leading to impaired blood flow and bacterial contamination

81

Appendicitis
Gross appearance

Appendix is enlarged with yellow-green exudate (pus)

82

Appendicitis
Histology

Transmural inflammation
Lots of PMNs and eosinophils

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