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Bloc E - GI & Metabolism > Feb14 M1-Histo lecture 2 > Flashcards

Feb14 M1-Histo lecture 2 Flashcards

1
Q

dx tool to distinguish the duodenum

A

Brunner’s glands (mucous glands) in the submucosa

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2
Q

dx tool to distinguish the jejunum

A

submucosa of dense CT (but no glands) pushes mucosa to make permanent plicae circularis (or valves of Kerkring)

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3
Q

ileum appearance on histo

A

plicae circularis get shorter and disappear

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4
Q

charact of SI mucosa

A

villi with small crypts at their base called crypts of Lieberkuhn (openings looking like circles on histo)

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5
Q

where’s the LP in SI mucosa + its characteristics

A

is loose CT (very cellular) fills the space under villi and between the crypts

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6
Q

Brunner’s gland fct in the duodenum

A

open near the crypts and make mucin that is rich in bicarb to neutralize acidic chyme from stomach

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7
Q

charact of serosa in the jejunum

A

infiltrated by fat tissue

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8
Q

rugae of the stomach vs plicae circularis of the jejunum

A

rugae disappear when stomach dilated

plicae circularis never disappear but simply pushed against the wall of the intestine

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9
Q

main concept in distinguishing the 3 parts of the SI

A

submucosa (Brunner’s or plicae or dimishing plicae)

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10
Q

SURFACE epithelium composition in the small intestine

A

simple columnar epithelium: absorptive enterocytes with striated border + mucus-secreting goblet cells

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11
Q

where are the stem cells in the small intestine (stomach = isthmus) + what they can do

A

in the crypts. can divide to make committed cells and then these committed cells (ex enterocytes) can divide outside of the crypts to make more cells like them

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12
Q

goblet cells charact

A

big, bulky, pale, mucous secreting

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13
Q

absorptive enterocytes charact

A

simple columnar epithelium, more abundant, brush border, nucleus at the basal side. cover the intestinal crypts

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14
Q

important charact of intestinal mucosa

A

form villi with lymphatics and blood capillaries inside them (in LP in middle of the villus)

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15
Q

turnover rate of intestinal mucosa epith and meaning

A

45 days. time needed for cells to migrate from base of crypt to top of villus and get sloughed off

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16
Q

clinical importance of turnover rate of intestinal epithelium

A

ANY cancer treatment of ANY cancer affects stem cells of gastric and intestinal mucosa and will get bleeding eventually

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17
Q

what allows motion of the villi in the SI

A

muscularis mucosa (SM)

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18
Q

name of lymphatics in villi and what are they made of

A

lacteals (lymphatic ‘‘capillaries’’): endothelial layer of squamous simple epithelium

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19
Q

intestinal stem cells on histology

A

pale cells at the base of the crypts, between the paneth cells

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20
Q

paneth cells charact and what creates them

A

(made by stem cells). zymogenic and have granules. make lysozymes to destroy bacterial walls + regulate intestinal flora

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21
Q

other cell type in middle of SI crypts + fct

A

enteroendocrine cells. face BM, like in stomach, and screte contents in LP

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22
Q

phenomenon observed in SI crypts

A

lot of mitosis (for future goblet cells or enterocytes)

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23
Q

how cell migration to lumen occurs in SI mucosa and what cells

A

all except Paneth cells. mature as they go to the lumen and push each other

24
Q

3 cell types in villi (simple columnar epithelium)

A
  1. columnar cells with brush border (absorptive enterocytes)
  2. goblet cells
  3. M cells (microfold cells)
25
Q

M cells function

A

associated (are near) with Peyer’s patches (GALT: gut associated lymphatic tissue)

26
Q

5 cell types in the SI mucosa crypts (simple columnar epithelium)

A
  1. absorptive enterocytes (columnar with brush border)
  2. goblet cells
  3. enteroendocrine cells
  4. paneth cells (lysozymes)
  5. stem cells
27
Q

important hormone released by SI crypts enteroendocrine cells + fct

A

CKK (cholecystokinin): contraction of gallbladder + promotes pancreatic secretions

28
Q

villi in duodenum (why different from rest of intestine

A

tortuous and a lot of rotations

29
Q

why jejunum has an even higher surface area for absorption

A

plicae circularis 1st level and then villi 2nd level

30
Q

Peyer’s patch def + location in duodenum vs ileum and colon vs appendix

A

concentration of lymphocytes, mainly T lymphocytes.
duod: are in LP
ileum and colon: are in submucosa
appendix: in submucosa but penetrate LP

31
Q

Paneth cells location and how to distinguish them

A

in intestinal crypts. granulated, nucleus at the base, foamy cytoplasm

32
Q

absorptive cells (enterocytes) on EM

A

striated border formed by microvilli

33
Q

microvilli what’s inside and what’s at their surface

A

inside: core of actin filaments

on surface: glycocalyx: glycoprotein coat

34
Q

4 important proteins in glycoprotein coat and what they do

A
  • enterokinase IN DUODENUM activates enzymes from pancreas
  • disaccharidases
  • dipeptidases
  • alkaline phosphatase (dissolve ether phosphate)
35
Q

why microvilli can have some contraction happening in them

A

actin filaments + bit of myosin

36
Q

2 elements for lipids (TGs) digestion + breakdown products

A
  • bile acids from the liver (to emulsify) + lipases from the pancreas.
  • gives glycerol, FAs and monoglycerides
37
Q

how lipid breakdown products handled in SI

A

enterocytes absorb, reassemble TGs in smooth ER, join to apoproteins to make and secrete chylomicrons that go to the liver

38
Q

how chylomicrons reach the liver (they circulate where)

A

go to lymph (lacteals), capillaries and portal veins too

39
Q

2 important pancreatic enzymes and what activates them

A

trypsinogen (trypsin) and pro-carboxypeptidase (carboxypeptidase).
activated by enterokinase

40
Q

M cells location and shape

A

in intestinal villi between between enterocytes. have infolding on basal side to accomodate for lymphocytes of GALT (gut associated lymphoid tissue) = Peyer’s patch

41
Q

how M cells work with GALT

A

internalize antigens and expose them on basal surface to T lymphocytes. stimulate prod of IgAs mainly and IgG too

42
Q

goblet cell on EM

A

mucous in apical cytoplasm + on surface to lubricate and protect intestinal surface (creates mucous coat)

43
Q

charact of epithelium in large intestine

A

no villi, crypts only. simple columnar epithelium

44
Q

where’s LP in LI

A

occupies space between

45
Q

muscularis mucosa in esophagus vs intestine and colon

A

esophagus: is longitudinal (along tube axis)

intestine and colon: circular

46
Q

5 cell types in colonal epithelium

A
  1. absorptive cells
  2. goblet cells
  3. entero-endocrine cells
  4. stem cells
    (5. Paneth cells ONLY at level of hepatic flexure)
47
Q

where are paneth cells in colon

A

hepatic flexure only

48
Q

submucosa charact in colon

A

loose and dense CT

49
Q

tunica muscularis charact in colon

A

forms bands of concentrated SM running along tube axis at specific places: tenia coli

50
Q

appendix connects to what portion of GI tract

A

cecum

51
Q

appendix epithelium charact

A

crypts like rest of LI but less abundant (simple columnar epith)

52
Q

GALT (lymphatic nodules) present where in the appendix

A

submucosa and disrupt muscularis mucosa and penetrate into the LP

53
Q

submucosa charact in appendix

A

infiltrated with fat

54
Q

tunica muscularis in appendix

A

inner circular and outer longitudinal

55
Q

complication of appendicitis

A

rupture of appendix wall and peritonitis

56
Q

why colitis and diarrhea are very bad

A

diseases of absorption of water (and lot of water put out in GI tube and reabsorbed) so lose a lot of water

57
Q

malignant tumors of the large bowel are mostly what cancers + epi stat

A

adenocarcinomas. 2nd most common cause of cancer death in North America.

Bloc E - GI & Metabolism (58 decks)

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