10/6 Histology Flashcards
how do plica increase surface area
3 fold by increasing the folds in the epithelium, present in colon, added to with villi in the small intestine, and even with folds in the submucosa in the small intestine
how are lipids handled in the lumen of the small intestines?
lipids will be emulsified by the bile acids, and difuse into the enterocytes and then made into triglyceride plus protein cover structure called chylomicron that is then diffused out of the cell and into the lymphatic capillary.
describe the epithelium of the small intestines
the epithelium cover villi and the surface and have a brush border of the microvilli, covering a columnar layer of enterocytes (absorptive columnar cells) also have goblet cells, Enteroendocrine cells, and paneth’s cells
what is the general feature of the small intestine surface?
villus sticking out that increase the surface area by 10 fold, covered by microvilli that will increase the surface are by 20-fold.
what does celiac disease do to the villi
leads to the shrinkage or loss of the villus (now it looks like a colon)
what are the absorptive columnar cells called?
enterocytes
describe the enterocytes
include: brush border, tight junctions, zonula adherens (terminal bar); desminsome; meidesmisome; gap junctions; Na,K-ATPase pump; K channel; AA carrier channels etc.
the cells at the base of the villi that are full of peptide that have anti-bacterial activities and maintain normal level of gut bacteria
the bright orange staining paneth cells at the base of the villi
associated with the stem cells and regulate the stem cells to keep them in the pathway of stem cells
paneth cells
stimulates HCO3 and H2O secretion by the pancreas and bile ducts
Secretin
stimulates pancreatic acinaar cell secretion and smooth muscle contraction by gall bladder. signal immediate satiety to the brain
CCK
stimulates the insulin secretion by beta cells in pancreas
GIP (glucose-dependent insulinotropic hormone)
signals long term satiety to the brain
peptide YY
a cell that releases secretin or CCK or GIP or peptide YY
enteroendocrine cells
under the epithelium cells, containing the plasma cells that are making anti-bodies
lamina propria
extensive blood supply, lymphatic and immune cells and smooth muscles that move these things around to pump thing around and stir things up are found here, just under the epithelium
lamina propria
thin band of smooth muscle just deep to the lamina propria and just deep to the deep glands of the small intestine
muscularis mucosae
the layer under the muscluaris mucosa
the submucosa, then the muscularis externa, and the adventita or serosa
cells in the duodenum that only make a pretective mucus
brunner’s glands
the largest number of the plica circularis or extensions of the glands into the lumen
in the jejunum
pathches that are full of lymphocytes that appear after birth and peak around 30 and lose these
peyer’s patches
where are peyer’s patches located?
in the ileum – look like little pyrimides of lymphatic cells that have no villi!
specialized cells in the peyer’s patches that have immune responsibilities
M or microfold cells that are specialized in bringing antogens from the lumen to the imune cells in layer under the endothelium
a general term for the lymphatic assiciated tissue in the intestines that helps mediate the immune response in the epithelium of the gut
MALT (mucosal associated lymphatic tissue) – called GALT (gut associated lymphatic tissue)
how do we get the immune response into the lumen of the gut?
IgA is taken up by the enteriocytes and transported across the epithelium and into the lumen.
area where max triglyceride and iron are absorbed
early in the duodenum
where are vitamin and B12 and GIF and bile salts absorbed?
Late, and in the ileum
where do digestive enzymes come form?
most from the exocrine pancreas, and from absorptive columnar cells containing a set of hydrolases on the brush border involved in end-stage digestion: disaccharidase, dipeptidase, etc.
found near the base of the glands unlike the stomach where they are near the top of glands
stem cells
control muscularis externa, if damaged motility is disrupted and swelling occures (hischsprung disease)
Myenteric plexi (auerbach’s plexi)