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GI > Histology > Flashcards

Histology Flashcards

1
Q

Three layers of GI mucosa?

A
  • epithelium
  • lamina propria
  • muscularis mucosa
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2
Q

Where is Meissner’s plexus found? Histo?

A
  • loose areolar CT of submucosa

- neurons with large pale nucleus, prominent nucleolus, basophilic cytoplasm

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3
Q

Where is Auerbach’s myenteric plexus found? Histo?

A
  • between inner circular and outer longitudinal smooth muscle of muscularis externa
  • motor neurons
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4
Q

Where are cardiac glands found in esophagus? Function?

A
  • lamina propria of beginning/end of esophagus

- protect non-kerat stratified squamous epithelium

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5
Q

What muscle is absent in upper 1/3 of esophagus?

A

muscularis mucosa (longitudinal in remainder of esophagus)

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6
Q

What is unique about submucosa in esophagus?

A

submucosal glands of mucoid nature throughout

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7
Q

How is muscle distributed in the esophageal muscularis externa?

A
  • upper 1/3 = skeletal
  • middle 1/3 = mix
  • lower 1/3 = smooth
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8
Q

What are the surface epithelial cells of the stomach? How does it interact with mucosa?

A
  • simple columnar

- invaginates to form gastric pits which are continuous with mucosal glands (cardiac) in mucosa

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9
Q

What mucosal layer is almost non-existent in the stomach?

A

lamina propria (tightly packed mucosal glands)

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10
Q

Three layers of muscularis externa in stomach?

A
  • innermost oblique layer
  • middle circular (thickening = pyloric sphincter)
  • outer longitudinal
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11
Q

What three cell types are found in the gastric glands of the stomach?

A
  • mucous neck cells
  • parietal cells
  • chief cells
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12
Q

Function of mucous neck cells in stomach?

A
  • secrete acidic mucous
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13
Q

Function of parietal cells in stomach? Location/histo?

A
  • lie between mucus neck cells
  • large round cells with central nucleus and pale acidophilic cytoplasm
  • secrete HCl and IF
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14
Q

Function of chief cells in stomach? Location? Control?

A
  • lower region of glands
  • basophilic cytoplasm (rER)
  • make pepsinogen
  • controlled by secretin and vagus nerve
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15
Q

What cell type produces peptide hormones in the gut? Distribution?

A
  • enteroendocrine cells

- dispersed throughout epithelium from stomach to colon, usually near base

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16
Q

Where do enteroendocrine cells release hormone?

A
  • NOT into the lumen

- secrete basally in a paracrine fashion or into underlying capillaries of lamina propria

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17
Q

Two mucosal specializations that increase SA of small intestine?

A
  • plicae circularis = semicircular folds of mucosa that extend into lumen (core = submucosa)
  • villi = outgrowths of mucosa (epi and LP)
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18
Q

Where are plicae circularis best developed?

A

jejunum (tall villi too)

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19
Q

What composes the core of villi?

A
  • loose CT

- central blind-ended lymphatic lacteal

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20
Q

Which layer does NOT extend into the villi?

A

muscularis mucosa

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21
Q

What are microvilli?

A

tiny evaginations of the apical membrane of enterocytes

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22
Q

What are the crypts of Lieberkuhn?

A
  • intestinal glands

- tubular invaginations of epithelium down into the lamina propria

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23
Q

How do secretions of intestinal glands reach the lumen?

A
  • epithelium of glands is continuous with that of villi

- small openings between villi

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24
Q

What is the predominant cell type covering the villi? Histo?

A
  • enterocytes

- tall columnar with basal nuclei and dense glycocalyx covering microvilli

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25
Q

How are enterocytes secured? life cycle?

A
  • junctional complexes between neighboring cells

- live for a few days during which they move from crypt to villus top to be sloughed

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26
Q

Where are goblet cells found? Function?

A
  • between enterocytes
  • increase in number from duodenum to ileum
  • secrete acidic mucous (lubricate, protect from panc enzymes/bact) = 80% carb, 20% protein
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27
Q

Where are paneth cells found? Life span?

A
  • base of crypts

- 20 days

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28
Q

What 3 compounds are released by Paneth cells? Function?

A
  • lysozyme stored in acidophilic granules
  • TNF-alpha
  • defensins
  • function is to control intestinal flora
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29
Q

What 2 hormones are released by enterendocrine cells in the stomach?

A

gastrin, somatostatin

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30
Q

Where are enteroendocrine cells found in the small intestine? 4 secretions?

A
  • concentrated in lower region of crypts

- CCK, GIP, motilin, secretin

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31
Q

What substances cross apical membrane of enterocytes by facilitated diffusion?

A

AA’s and monosaccharides

32
Q

What substances cross apical membrane of enterocytes passively?

A

small lipids (larger through pinocytosis)

33
Q

How are lipids processed in the enterocytes?

A
  • monoglycerides and FA’s collect in EC sER where they are resyn into triglycerides and assembled into chylomicrons
  • chylo’s are packaged into vesicles by Golgi and moved to basolateral membrane for exocytosis –> lymph capillaries
34
Q

What happens to AA’s, mono’s, and small FA’s in the enterocyte?

A

cross basolateral membrane to reach lamina propria where they enter blood and lymphatic capillaries

35
Q

How does lamina propria change prox - distal in the small intestine? Unique structure in ileum?

A
  • inc in lymphoid tissue due to inc epithelial permeability

- Peyer’s patches

36
Q

What specific submucosal glands are found only in the duodenum? Function?

A

BRUNNER - serous/mucus alkaline fluid that raises pH of intestinal chyme

37
Q

What initiates activity of the muscularis externa in the small intestine?

A

distension

38
Q

What two things are NOT found in the LI?

A

villi, Paneth cells

39
Q

What cell type increases prox - distal in the LI?

A

goblet cells

40
Q

Two unique morphological characteristics of appendix?

A
  • complete ring of lymphoid tissues in lamina propria

- complete outer longitudinal muscle layer

41
Q

Difference in epithelial cell type of cutaneous lip vs. red region at vermillion border? Accessory structures?

A
  • both strat squamous
  • kerat vs. non-kerat
  • cutaneous contains hair follicles, seb and sweat glands
  • red contains BV’s responsible for color
42
Q

Function of lip/cheek submucosa? What does it contain?

A
  • binds mucosa to overlying muscle in order to prevent formation of folds during mastication (dec risk of biting cheek)
  • glands
43
Q

Gingiva cell type? How are the gums bound to alveolar bone?

A
  • kerat strat squamous
  • lamina propria contains thick collagen fibers that blend with periosteum
  • no glands, no submucosa
44
Q

Epi cell type in hard vs. soft palate?

A
  • kerat strat squamous

- non-kerat strat squamous

45
Q

How is the hard palate mucosa attached to bone?

A
  • lamina propria binds periosteum

- forms mucoperiosteum

46
Q

What additional fibers are found in soft palate?

A

skeletal muscle

47
Q

Four types of lingual papillae found on anterior 2/3 of tongue?

A

filiform, fungiform, circumvallate, foliate

48
Q

Composition of tongue?

A
  • mass of skeletal muscle covered by mucosa

- muscle fibers in long, transverse and oblique planes

49
Q

Most numerous type of papillae?

A

filiform

50
Q

Which papillae has narrow, conical shape, is present on entire ant 2/3, lacks taste buds, and is keratinized?

A

FILIFORM

51
Q

Fungiform taste bud location? What happens to these papillae with age?

A
  • apical surface

- surface keratinizes with age

52
Q

How is the lamina propria arranged in fungiform papillae?

A
  • extends into papilla

- BV’s reach close to surface

53
Q

Which papillae type is rare in adult humans?

A

Foliate

54
Q

Buds and location of foliate papillae?

A
  • richly endowed

- posteriorly on lateral borders of tongue

55
Q

Where are circumvallate papillae found? Cell type?

A
  • 8-12 ant to sulcus terminalis

- strat squamous epithelium

56
Q

What is found on lateral wall of circumvallate papillae?

A

numerous taste buds

57
Q

What special structure is associated with circumvallate papillae? Function?

A
  • serous con Ebner’s glands which bathe taste buds in fluid - wash out tastants
  • ducts open into floor of each circular furrow
58
Q

Developmental progression of taste bud cells?

A

basal –> supporting –> receptor

59
Q

Lifetime of taste receptor cells?

A

10-14 days

60
Q

What CN’s contribute to taste receptor cell AFF nerve terminal?

A

VII, IX, X

61
Q

Which 2 aspects of salivary gland organization are surrounded by myoepithelial cells?

A

acinus and intercalated duct

62
Q

Why are the striated ducts ‘striated’?

A
  • has lots of basal infoldings due to plentiful mito

- energy require for lots of ion exchange modifying composition of secretory product

63
Q

At what point does the salivary duct system become purely conductive?

A
  • interlobular ducts

- inc CT component, absent striations

64
Q

Secretory products of the salivary glands?

A
  • submandibular = mixed
  • sublingual = mucous
  • parotid = serous
65
Q

What percentages of saliva are contributed by the glands?

A
  • Parotid = 30%

- submandibular = 60%

66
Q

What happens to the parotid glands over time?

A

invaded by adipose after 40 years

67
Q

What covers dentin?

A
  • superiorly enamel

- inferiorly cementum

68
Q

How is tooth held in socket?

A

periodontal ligament attaches to uncalcified outer layer of cementum

69
Q

What cells line the pulp cavity? Function?

A
  • odontoblasts

- make dentin = 2nd hardest compound in body (after enamel)

70
Q

Secretions of odontoblasts?

A
  • secrete apically

- Type I collagen, proteoglycans, glycoproteins = ORGANIC dentin

71
Q

When does mineralization of pre-dentin secreted apically by odontoblasts occur?

A
  • when matrix vesicles containing calcium and phosphate are released from odontoblasts
72
Q

Percent composition of enamel?

A

96% mineral

73
Q

What composes the 4% organic component of enamel?

A
  • NO collagen

- keratin-like glycoproteins = amelogen, enamellin

74
Q

What cells secrete enamel? When?

A
  • ameloblasts (reversed polarity from odontoblasts)

- only during tooth development

75
Q

What does cementum consist of?

A
  • calcified collagenous fibrils and trapped osteocyte-like cementocytes

GI (5 decks)

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