lect 32 & 33-Upper GI histology Flashcards

1
Q

what is the epithelium of the GI tract

A

stratified squamous at either end

simple columnar most of the length

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2
Q

what type of muscle is in the GI tract

A

skeletal at either end (including upper esophagus)

smooth muscle throughout most of length

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3
Q

what is the GI intrinsic rhymicity mostly due to

A

presence of an enteric nervous system that exists independently of external influences including ANS

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4
Q

what are the peptide neurotransmitters

A

bombesin
motilin
vasoactive intestinal peptide

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5
Q

what do unicellular endocrine cells secrete

A

secrete neuropeptides

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6
Q

what are unicellular endocrine cells derived from

A

endoderm

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7
Q

what are intrinsic nerve fibers derived from

A

neural crest

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8
Q

what does the mucus membrane of the lip consist of

A

stratified squamous epithelium
basement membrane
lamina propria

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9
Q

what 3 embryonic tissues interact in the development of teeth

A

ectoderm, neural crest and mesoderm

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10
Q

what gves rise to dental papilla

A

neural crest and mesoderm

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11
Q

what forms the enamel organ

A

ectoderm

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12
Q

what is the dental primordium formed from

A

basal cels of the oral ectoderm

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13
Q

what is the labiodental lamina

A

epithelial shelf that grows from the thickening primordial into the mesenchyme as a bifid structure

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14
Q

what is the dental lamina

A

internal limb (teeth)

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15
Q

what is the dental sac

A

CT sac surrounding the enamel organ and dental papilla and forms cementum and the periodontal membrane

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16
Q

what forms the dentin matrix through the life of the tooth

A

odontoblasts

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17
Q

define tomes’ dentinal fibers

A

cytoplasmic extensions of the odontoblasts continuing through the predentin and dentinal layers to the dentin-enamel junction

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18
Q

what type of collagen in dentin primarily composed of

A

collagen type 1

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19
Q

what forms the enamel which covers only the tooth crown

A

ameloblasts

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20
Q

what is the hardest substance in the body

A

enamel

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21
Q

what organic components are unique to enamel and are removed after calcification

A

amelogenins and enamelins

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22
Q

what does pulp originate from

A

dental papilla containing condensed mesenchyme

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23
Q

what is the periodontal membrane

A

CT formed from dental sac with fibroblasts, osteoblasts, cementoblasts, collagen fibers, blood vessels and nerve vessels

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24
Q

what binds the cementum to the bony socket

A

periodontal membrane

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25
Q

what separates the anterior 2/3 of the upper oral portio of the tongue from the posterior 1/3

A

sulcus terminalis

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26
Q

what are lingual papillae formed of

A

central core of CT lamina propria covered by stratified squamous epithelium

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27
Q

what are the 2 types of cells of taste buds

A

sustantacular cells and taste cells

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28
Q

what are sustentacular cells

A

taste bud cells that are spindle-shaped support cells and arranged like barrel-staves to surround the inner taste pore at the base

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29
Q

what does the basal part of taste cells secrete

A

neurotransmitters

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30
Q

what do salt and sour taste sensations use as a signal transduction mechanism

A

ionic transport

31
Q

what does sour taste sensation involve

A

hydrogen ion blockage of potassium ion channels to cause depolarization

32
Q

what does bitter taste involve

A

gustucin (homologue of retinal transducer)
involves activates of Galpha subunit, decrease in cGMP, and closure of sodium channels and hypo polarization of the taste cells

33
Q

what type of epithelium is in the mucosa of the digestive tube

A

stratified squamous transitioning to simple columnar

34
Q

what type of tissue is in the lamina propria of the digestive tubule

A

loose areolar CT associated with epithelium

35
Q

what type of tissue in in the submucosa of the digestive tube

A

dense, irregular CT

36
Q

what nerve plexus is located in the submucosa of the digestive tube

A

meissner’s plexus

37
Q

what are the functions of muscular is externa

A

regulates size of lumen

regulates rhythmic movement of GI tract

38
Q

what is tissue of the serosa of the digest tube

A

dense irregular CT

layer of submesothelial Ct

39
Q

what time of tissue is in the adventitia of the digestive tube

A

dense irregular CT with adipose tissue

40
Q

what is the sympathetic innervation of the gut wall

A

sympathetic postganglionic fibers pass through gut wall to glands and smooth muscle

41
Q

what is the parasympathetic innervation of the gut wall

A

preganglionic fibers synapse with postganglionic fibers in ganglia within the gut wall itself

42
Q

what does the meissner’s plexus regulate

A

local secretion, blood flow and absorption

43
Q

what does the auerbach’s plexus do

A

coordinates muscular activity of gut wall

44
Q

what is the first line of defense in the gut-associated lymphoid tissue

A

IgA

45
Q

what secretes IgA

A

antigen-stimulated B cells in the follicle of the lamina propria

46
Q

what are the functions of the esophagus

A

digestion (initiated in the mouth)

addition of mucous to food bolus

47
Q

what type of epithelium is in the mucosa of the esophagus

A

stratified squamous nonkeratinized epithelium

48
Q

what are rugae

A

longitudinal mucosal folds that are most prominent in an empty stomach

49
Q

where do gastric glands open into

A

gastric pits

50
Q

what type of glands does the cardia of the stomach contain

A

mostly mucous glands

51
Q

what type of glands are in the funds of the stomach

A

gastric glands

52
Q

what type of glands are contained in the body of the stomach

A

gastric glands

53
Q

what type of glands are contained in the pylorus of the stomach

A

mucous glands and hormone-secreting enteroendocrine cells

54
Q

what do chief cells secrete

A

pepsinogen

55
Q

what do parietal cells manufacture

A

HCL

56
Q

what secretes intrinsic factor

A

parietal cells

57
Q

what do enteroendocrine cells do

A

diffuse neuroendocrine cells that secrete hormones and secrete serotonin

58
Q

where are mucous neck cells located

A

in the narrow portion of the gland near the gastric pit

59
Q

what type of epithelium lines the surface of the stomach and the pit

A

simple columnar consisting of surface mucous cells

60
Q

where do chief cells predominate

A

end portion of gastric gland

61
Q

how are parietal cells shaped

A

large pyramidal shaped, eosinophilic cells

62
Q

what are common ways to increase surface area for absorption in GI tract

A
increase length of small and large intestines
plicae circulares (valves of kerckring)
villi and microvilli
63
Q

define plicae

A

folds of the mucosa, each with a submucosal core

64
Q

where do the crypts extend

A

down between the villi below the bases of the villi

65
Q

what is the epithelium of the wall of villus in the crypt-villus system

A

simple columnar epithelium

66
Q

what type of plexus does each villus have of the crypt-villus system

A

capillary plexus

67
Q

what is the blind-ending lympathic in each villus called

A

lacteal

68
Q

define glycocalyx

A

glycolipid coat that contains an array of brush border enzymes: maltose, sucrase, isomaltase, lactase, lipase, peptidases

69
Q

what is glycocalyx produced by

A

small intestine epithelial cells (enderocytes)

70
Q

what are the microvilli in the small intestine supported by

A

actin filaments

71
Q

how are actin filaments tied to terminal web intermediate filaments

A

via spectrin fibrils

72
Q

what membrane-linking proteins bind actin filaments to plasma membrane covering the villus

A

myosin I and calmodulin

73
Q

what actin cross-linking proteins are used to bind actin filaments to each other

A

villain and fimbrin