histology II Flashcards

1
Q

small intestines increased surface area

A
  • microvilli: extensions of cytoplasm, striate border of simple columnar epithleium
  • villi: evaginations of mucosa w/core of lamina propria (exclusive to small intestines)
  • plicae circulares- circular folds of entire mucosa, w/core of submucosa, permanent projections, begin in proxiimal duodenum, diminish until absent in distal ilieum
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2
Q

small intestines exocrine glands

A

pancreas and liver

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3
Q

small intestines submucosal glands

A
duodenal glands (brunners) only in submucosa of duodenum
secrete mucous
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4
Q

intestinal crypts

A

aka mucosal glands
epithelium invaginating into lamina propria
small and large intestines

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5
Q

small intestines- epi

A

simple columnar epithelium
surface epi replaced every 3-7 days
cells:
-absorptive columnar cells (microvillous border)
-goblet cells (lining surface and dipping into crypts)
-lymphocytes (visible migrating from lamina propria to lumen)
-enteroendocrine cells
-paneth cells
-M cells

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6
Q

enteroendocrine cells

A
mainly in crypts, rarely in villus
basolateral
secrete into vascular channels in lamina propria 
products:
incretins (k-cells)
GIP (L-cells)
serotonin (enterochromaffin cells)
motilin
cholecystokinin
neurotensin
VIP
subtance P
endorphins
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7
Q

paneth cells

A
found in base of intestinal crypts
contain large acidophilic granules
function not well defined
secrete enzyme lysozyme and peptide defesins- degrase components of bacteria cell wall
apical into lumen
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8
Q

M cells

A

specialized cells in epi
limited, small microfolds
part of innate and classic immune systmes, actively capture/transport Ags to APCs and B cells in lamina propria

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9
Q

small intestines- mucosa

A

lamina propria
loose CT, prone to lymphoid infiltration
large numbers of plasma cells -> produce secretory IgA -> transported into intestinal lumen
lacteals (blind villi lymphatic capillaries)

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10
Q

lymph nodules of small intestines

A

more numerous distally
macroscopic aggregates of lymp tissue called peyers patches (only in small intestine)
lots in ileum
M cells more prevalent here

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11
Q

small intestines- submucosa

A

projects into pllicae circulares
infiltrates w/lympocytes at peyers patches
submucosal glands found only in duodenum

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12
Q

small intestines- serosa

A

duodenum has serosa on anterior surface only -> retroperitoneal
jejunum and ileum have serosa

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13
Q

ileocecal junctions

A

site where ileum joins large intestine
formed by folds of mucosa and submucosa
supported by mass of circular smooth m from muscularis externa

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14
Q

appendix

A
slender blind diverticulum of cecum
small irregular lumen often containing cellular debris
villli absent
intestinal crypts
enteroendocrine cells
some paneth cells
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15
Q

appendix histology

A
simple columnar epi w/goblet cells
lymphoid tissue occupies lamina propria
muscualris mucosae often incomplete
submucosa is thick 
thin muscularis externa (usually 2 layers)
serosa
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16
Q

intestinal crypts- large intestine

A

crypts of lieberkuhn
longer and more closely packed than in small intestine
occasional enteroendocrin cells
paneth cells absent

17
Q

large intestine epi

A

simple columnar epithelium w/more goblet cells then in small intestines
no digestive ezymes secreted

18
Q

plica criculares large intestine

A

not present!

plica semilunares in colon -> sacculations/haustra

19
Q

colon

A

scattered lymph nodules
muscularis externa incomplete:
-inner layer completely encircels submucosa,
-outer longitudinal layer in 3 longitudinal bands -> taeniae coli
serosa on ant surface
appendices epiploicae

20
Q

rectum

A

muscualris extena compete (no taeniae coli)
serosa present on upper 1/3
anterior surface in middle 1/3
absent from .ower 1/3
plicae transversales (2 on left, 1 on right)
ends as it exits the body, no histological changes, before pectinate line

21
Q

rectum/anal jnx

A

intestinal crupts decrease, and disappear

mucous membrane froms longitudinal folds known as rectal columns

22
Q

pectinate line

A

simple epithelium becomes stratified squamous non-cornified continuous w/epi of skin

23
Q

anal canal

A

submucosal CT contains:
-subepithelial circumanal glands
-longitudinal thin-walled vv -> hemoroids
muscularis extera- internal layer thickens to form internal anal sphincter, external sphincter formed by skeletal m

24
Q

anal verge

A

caudal portion of anal canal
changes to stratified squamous epithelium, keratinized
sweat glands, hair follicles, sebaceous glands