Gross Histology of Alimentary Tract Flashcards
Lamina propria
Loose tissue that contains blood vessel and connective tissue in which surface epithelium of gut sits
Muscularis mucosae
the muscle that lies around the lamina propria and surface epithelium
3 components of GI mucosa
surface epithelium, lamina propria, muscularis mucosae
Layers of vsiceral gut (7)
adventitia or serosal layer, outer longitudinal muscle, inner circular muscle, submucosa, muscularis mucosae, lamina propria, surface epithelium
Nerve plexi of visceral gut (2)
submucosal nerve plexus, myenteric plexus (between two muscle layers)
3 ways cells stick together
tight junctions, desmosomes, shared cell wall + gap junction
Network of sealing protein fibers of transmembrane proteins embedded in plasma membranes of two cells with extracellular domains joining one another directly
tight junction
Molecular complexes of cell adhesion proteins and linking proteins that attach the cell surface adhesion proteins to intracellular keratin cytoskeletal filaments
desmosomes
Direct connections of cytoplasm of two cells via hydrophilic channels which allow molecules and ions to pass freely between.
gap junctions
Is there secretion in the esophagus
A little
Is there absorption in the esophagus
No
Gastric pits
holes in the rugal folds of stomach that are the conduit of gastric glands
_____ acid is produced by _____ cells in the stomach.
hypochloric acid produced by parietal cells
Parietal cells are stimulated to produce acid by ____ and _____ in the stomach
histamine and gastrin
Gastrin is secreted by _____ cells into the blood stream.
stomach antral neuroendocrine cells
____ acts directly on parietal cells and stimulates enterochromaffin like cells in the corpus of the stomach.
Gastrin
Enterochromaffin like cells in the stomach excrete ____
histamine
Another name for mucosa of the fundus
oxyntic mucosa
Are there inflammatory cells in the normal lamina propria?
No
Chief cells in the stomach produce ____
pepsinogen
Gastric pits are lined by _____ epithelium
foveolar
Defining feature of small intestine epithelium
Fingerform villi with epithelium outside and crypts with epithelium inside
4 mechanisms of absorption
passive diffusion, facilitated passive diffusion, active transport, pinocytosis
_____ in lamina propria absorb dietary lipids into the lymphatic system from the small intestine.
Lymph vessels/lacteals
_____ cells in the small intestine provide phagocytosis and intracellular digestion of intestinal microorganisms.
Paneth
_____ glands in the duodenum produce a mucus-rich alkaline secretion containing bicarbonate that has 2 functions.
Brunner glands in the duodenal submucosa
- protection from gastric acid
- alcalization to allow digestive enzymes to work
Molecules absorbed in colon
water, sodium, chloride
Molecules secreted in colon
bicarbonate, mucus
____ cells secrete mucus in response to tactile stimuli from luminal contents, lubricant that protects the epithelium, and binds ingested material to form feces in the colon.
goblet
Are there villi in the colon?
No –> only crypts
Are inflammatory cells in the lamina propria of the colon normal?
Yes- -> can have none all the way up to a lot
Lymphoid tissue associated with mucosa is called ____
mucosa associated lymphoid tissue (MALT) –> very protective from all the goop in the GI tract
In MALT, antigenic material is exposed to ___ cells which are associated in antigen transport and antigen presentation in the lymphoid tissue.
M cells
Lymph follicles that become large and frequent in the bowel are called _____
peyer patches
Stimulation of B lymphocytes leads to the production of Ig ___ and ___ in the peyer patches, preventing adherence of bacteria and viruses to the epithelium.
IgA and IgM
The major effector mechanism of MALT
direct secretion of IgA onto mucosal epithelia
The activity of ______ in follicle-associated epithelium of intestine is the key to MALT immunity.
germinal centers
Is there lymph tissue in the esophagus
Not really –> rarely have follicles in epithelium but have accumulation of intraepithelial lymphocytes in reflux disease
Are there lymphoid tissues in the stomach
Not usually –> accumulation of lymphoid cells can occur in chronic gastritis
Normal location of lymphoid tissue in small intestine.
lamina propria, villi, in between crypts; large aggregates in peyer’s patches in ilium // in celiac disease, T cells accumulate in surface epithelium
Normal location of lymphoid tissue in colon..
lamina propria with mucosal and submucosal follicles // in lymphocytic colitis, T cells accumulate in surface epithelium
