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GI tract: Small Intestine - Coggle Diagram
GI tract: Small Intestine
T. mucosa
villi
leaf/finger-like projections of T. mucosa
10x increase in intestinal surface
central lacteal
blind-ended lymphatic in center of vilus
transports chylomicrons
surrounded by capillary network
smooth mm strands "pump" villus of lymph
epithelium + lamina propria
glands
L. propria contains reticular fibers and free cells
highly cellular
lymphatic nodules found throughout, increase caudally
aggregates = peyer's patches, characteristic of
ileum
muscularis mucosa
2+ layers smooth mm.
submucosa
intestinal submucosa glands (Brunner's)
cranial SI
simple branches tubuloacinar glands
open into base of intestinal mucosal glands
secretory cells contain apical membrane-bound granules and basal RER
glands
secretion is mucous, serous, or mixed
contains protective substances (mucus, bicarb)
buffers stomach acid
optimize action of pancreatic enzymes
part of intestinal mucosal barrier to protect epithelium
nervous plexus present
plicae circularis
folds of mucosa and submucosa
increase surface area of jejeunum
epithelium
undifferentiated crypt cells (stem cells)
located in basal portion of gland
divide to make differentiated epithelial cells of gland and surface
replace intestinal epithelium every few days
Goblet cells
enteroendocrine cells
scattered singularly
hormonal regulation of GI function
Paneth cells
found only in the base of the gland
granules with lysozyme and peptidase
M cells
over lymphatic nodules
take up antigens to pass to lymphocytes
intraepithelial lymphocytes
enterocyte
numerous on surface villi
columnar with apical microvilli
filamentous
apical tight junctions
seals gut lumen
basal nucleus
many mitochondria
glycocalyx covering to anchor enzymes
