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Flashcards in histology II Deck (24):
1

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

2

small intestines exocrine glands

pancreas and liver

3

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

5

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

6

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

7

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

8

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

9

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)

10

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

12

small intestines- serosa

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

13

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

14

appendix

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

15

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

16

intestinal crypts- large intestine

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

17

large intestine epi

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

18

plica criculares large intestine

not present!
plica semilunares in colon -> sacculations/haustra

19

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

20

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

24

anal verge

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