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Gastrointestinal DF > Histology of The lower GI tract > Flashcards

Histology of The lower GI tract Flashcards

1
Q

4 degrees of folding in SI

A

1) plicae circularis (mucosa and submucosa)
2) intestinal villi (folds of mucosa)
3) intestinal glands: crypts of lieberkuhn (between villi)
4) microvilli on the apical surface of enterocytes

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2
Q

what are enterocytes?

A

epithelial cells lining the lumen

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3
Q

plicae circularis begin in the ____ are distinct in the ____ and disappear in the ____

A

duodenum, jejunum, mid-ileum

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4
Q

intestinal glads are formed by what?

A

crypts of lieberkuhm are formed by invaginations of the mucosa between adjacent intestinal villi

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5
Q

cells of the crypts of lieberkuhn

A

paneth cells, absorptive cells, goblet cells, enteroendocrine cells

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6
Q

microvilli are what

A

evaginations of the apical part of the enterocytes to increase SA
-produce a brush border on the apical border of enterocytes

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7
Q

serosa makeup

A

thin layer of loose CT covered by visceral peritoneum (mesothelium)

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8
Q

arterioles derived from the submucosal plexus enter the mucosa of the SI and give rise to 2 capillary networks?

A

1) the villus capillary plexus: supplies intestinal villus and upper portion of crypts of lieberkuhn
2) pericryptal capillary plexus: supplies lower half of crypts of lieberkuhn

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9
Q

lacteal location

A
  • core of the villus
  • just above muscularis mucosae is the lymphatic plexus whose branches surround lymphoid nodule in the submucosa
  • efferent vessels anastomose with the lacteal and exit digestive tube together with BV
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10
Q

Lacteal Function

A

convey chyle (lymph containing lipids absorbed from the meal and packaged in chylomicrons) from SI to lymphatic circulation—>thoracic duct—>systemic circulation

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11
Q

What is chyme?

A

semifluid mass of partly digested food expelled by the stomach into the duodenum

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12
Q

duodenum histologic features

A

Brunner’s glands (mucous) in submucosa
few goblet cells
leaflike villi

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13
Q

jejunum histologic features

A

well eveloped plicae circulares
irregeular villi
more goblet cells
no brunner’s glands (no glands submucosa) or peyer’s patches

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14
Q

ileum histologic features

A

many peyer’s patches in lamina propria and submucosa
finger-like villi (short)
most goblet cells

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15
Q

villi and crypts of lieberkuhn lined by ____ ____ ___ with 4 cell types

A

simple columnar epithelium

1) absorptive enterocyte cells
2) goblet cells
3) paneth cells
4) enteroendocrine cells

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16
Q

cells found in the crypts of lieberkuhn

A

PES

paneth cells, enteroendocrine cells, stem cells

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17
Q

microvilli on enterocyte cells contain?

A

intramembranous enzymes, including lactase, maltase, sucrase for digestion of carbs

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18
Q

lactose intolerance

A

no lactase present, bacteria ferment lactose which causes gas and organic acids lead to irritation and increased motility, water also stays in for diarrhea

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19
Q

goblet cells: cell type, location, secretory product

A
  • columnar mucus secreting cells scattered among enterocytes of intestinal epithelium
  • secretes glycoproteins (80% carbs 20% proteins) released by exocytosis
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20
Q

mucus from goblet cell function

A

forms protective gel coat to shield epithelium from abrasion and bacterial invasion, can trap bacteria, protects enterocytes

21
Q

enteroendocrine cells secrete what

A

gastrin, secretin, CCK

22
Q

gastrin

A

stimulates gastric motility, HCL and insulin

23
Q

secretin

A

stimulates pancreatic bicarb secretion, enhances insulin secretion

24
Q

CCK

A

acts on pyloric sphincter to slow emptying

-stimulates release of bile and pancreatic enzymes

25
Q

paneth cells secrete

A

antimicrobial proteins to limit bacteria-enterocyte contact

26
Q

antimicrobial proteins action and storage

A

kill bacteria by enzymatic degradation of the bacterial wall or by disrupting the bacterial inner membrane
-retained in intestinal mucus blanket

27
Q

SI is protected from pathogens by:

A

GAP PIT V

Gastric juice acidity inactivates ingested microorganisms
Antimicrobial proteins from paneth cells
Peyer’s patches particip. in cell surveillance of antigens

Peristalsis prevents bacterial colonization
IgA neutralizes antigens
Tight junction barrier of intestine links adjac. enterocytes

Viscous gel-like blanket produced by goblet cells

If any of these are knocked out, then it can lead to a disease process

28
Q

IBD

1) initial alteration
2) inflamm process
3) accumulation

A

initial alteration is infiltration of neutrophils into crypts of lieberkuhn–>destorys intestinal glands by forming crypt abscesses and atrophy and ulceration of mucosa

  • inflammatory process also infiltrates submucosa and muscularis
  • accumulation of lymphocytes forms aggregates of cells (granulomas)
29
Q

complications of IBD

-crohn’s segments

A
  • occlusion of intestinal lumen by fibrosis and formation of fistulas in other segments of SI
  • segments affected by crohn’s disease are separated by normal stretches of intestinal segments
30
Q

technique to replace bad bacteria with good bacteria and what bacteria usually is the bad one

A

C. Diff and use fecal microbiota transplant

31
Q

large intetine histologic features

A

mucosa of LU lined by simple columnar epithelium from enterocytes and abundant goblet cells
enterocytes have short apical microilli

32
Q

major function of enterocytes in LI

A

transport of ions and water

33
Q

what is not found beyond the ileocecal valve?

A

plicae circulares and intestinal villi

34
Q

what is characteristic of the mucosa of the colon

A

numerous openings of straight tubular glands or crypts of Lieb.
-much deeper here than in SI
have high proportion of goblet cells

35
Q

main function of LI

A

absorption of water, sodium, vitamins, and minerals

-active transport of sodium removes water and concentrates chyme into semisolid feces

36
Q

4 cell types of colon mucosa

A

1) simple columnar absorptive cells with SHORT apical microvilli (enterocytes)

2) stem cells
3) predominant goblet cells
4) enteroendocrine cells

37
Q

regions of colon are facilitated by PM channels that are regulated by _____. and explain process

A

mineralocorticoids such as aldosterone inserts Na+ channels to increase absorption of Na+

38
Q

glands of Lieb in LI contain what cells

A

goblet ells, enteroendocrine cells, stem cells

no paneth cells (may be some in cecum)

39
Q

taeniae coli is formed by what

A

fused bundles of outer smooth muscle layer

40
Q

contraction of taeniae coli and inner circular smooth muscle produces?

A

haustra

41
Q

appendix function

A

may be safehouse for good bacteria

42
Q

appendix most important features

A

thickening of its wall due to large accumulations of lymphoid tissue in lamina propria and submucosa

43
Q

appendix hist features

A

villi absent, crypts not frequent, fatty tissue in submucosa

44
Q

appendix mucularis externa

A

thinner than reminder of LI and outer SM layer does not aggregate into taenia coli

45
Q

ano-rectal junction

A

simple columnar epithelium of rectal mucosa replaced by stratified squamous epithelium

46
Q

formation of internal anal sphincter

A

inner circular layer of SM in the ano-rectal junction thickens to form the internal anal sphincter

47
Q

anal region is lined by what

A

keratinized stratified squamous epithelium and submucosa contains sebaceous and sweat glands

48
Q

gene responsible for familial polyposis and colorectal tumorigeneis

A

APC gene

49
Q

colorectal tumor location

A

where it develops in the colon and then spreads bsed off lymph and venous drainage of section of colon. this determines what area it will affect next

Gastrointestinal DF (14 decks)

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