Intestinal Histology Flashcards
microvili
cytoplasmic projections of cell membrane of the simple columnar epithelium
increase SA
Vili
evaginations of mucosa (multicellular)
project into lumen—>increase SA
shape varies by location (ONLY FOUND IN SI)
*create invaginations called intestinal crypts (location for progenitor cells)
Plicae circulares
(SI) circular folds of entire mucosa and submucosa that project into lumn
diminish in size as you move down intestine
Brunner’s glands (duodenal glands)
glands found only in the submucosa of duo that secrete high pH mucus to prevent damage from stomach acid
enteroendocrine cells
found in the crypts of the SI
secrete product into lamina propria—>picked up by vascular organs (ENDOCRINE ORGAN)
incretins, GIP, 5HT, motilin …..
Paneth cells
found in base of intestinal crypts
have large apical granules that secrete lysozyme, defensins into lumen (help degrade bacteria found in food stuffs)
M cells
specialized epithelial cell that act with the innate immune system and present them to APCs and B cells
lamina propria of Si
loose CT that contains lots of lymphatic tissue where IgA
also includes lacteals, capillaries, nerves
Peyer’s patches
nodular infiltrates of lymphatic tissue found within the lamina propria of the SI
esp found in the ileum
high density of M cells
appendix
mucosal lining with gut epithelium
NO vili, some crypts with enteroendocrine cells and paneth cells
Plica semilunares
folds created by tenia coli contraction
they are the folds b/w haustra
serosa of the rectum
present on the upper 1/3 and anterior 1/3 only (peritoneal part)
absent on lower rectum/anus
rectum histology
same general concept as large intestine however there are NO taeniae coli, they have re-expanded to form an outer muscular layer
Plicae transversales
transverse folds of mucosa bulge into the lumen
2 on L
1 on R
rectoanal junction
rectum ends where it pierces the body wall (perineum)
intestinal crypts decrease and disappear
presence of rectal columns
