Flashcards in histology II Deck (24):
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small intestines increased surface area
-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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small intestines exocrine glands
pancreas and liver
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small intestines submucosal glands
duodenal glands (brunners) only in submucosa of duodenum
secrete mucous
4
intestinal crypts
aka mucosal glands
epithelium invaginating into lamina propria
small and large intestines
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small intestines- epi
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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enteroendocrine cells
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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paneth cells
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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M cells
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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small intestines- mucosa
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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lymph nodules of small intestines
more numerous distally
macroscopic aggregates of lymp tissue called peyers patches (only in small intestine)
lots in ileum
M cells more prevalent here
11
small intestines- submucosa
projects into pllicae circulares
infiltrates w/lympocytes at peyers patches
submucosal glands found only in duodenum
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small intestines- serosa
duodenum has serosa on anterior surface only -> retroperitoneal
jejunum and ileum have serosa
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ileocecal junctions
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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appendix
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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appendix histology
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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intestinal crypts- large intestine
crypts of lieberkuhn
longer and more closely packed than in small intestine
occasional enteroendocrin cells
paneth cells absent
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large intestine epi
simple columnar epithelium w/more goblet cells then in small intestines
no digestive ezymes secreted
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plica criculares large intestine
not present!
plica semilunares in colon -> sacculations/haustra
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colon
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
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rectum
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
rectum/anal jnx
intestinal crupts decrease, and disappear
mucous membrane froms longitudinal folds known as rectal columns
22
pectinate line
simple epithelium becomes stratified squamous non-cornified continuous w/epi of skin
23
anal canal
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
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