Digestive System Flashcards
What are the three main layers of the GI tract starting from the lumen?
- Mucosa: made up of epithelium (lines lumen), lamina propria and muscularis mucosae (smooth muscle, thin layer 2-3 layers)
- submucosa: dense CT vascular
- muscularis: made up of circular muscle and longitudinal muscle (both smooth muscle)
- Serosa: adventia, loose CT
what type of epithelium is the mucosa layer?
simple columnar epithelium (this is what lines SI and LI, esophagus differs).
brunners glands are only located where?
duodenum (first part of SI), intestinal glands also here. brunners glands located no where else but other parts have intestinal glands.
how long is the avg esophagus? does absorption occur here? it is lined by?
around 25cm
NO
stratified squamous non keratinized epithelium
esophagogastric junction marks the point where?
esophagus (stratified squamous non keratinized epithelium) becomes simple columnar epithelium (which is what lines stomach)
what is the cardia?
point where esophagus becomes stomach
what are the three parts of the stomach?
fundus (top of stomach)
body
pylorus (distal, goes to duodenum)
what type of folding is in the stomach?
gastric rugae (longitudinal folds) allows stomach to contract and expand
it is important for the esophagus to be protected from what?
acid (stratified squamous non keratinized epithelium helps do this)
what are gastric pits?
glands of the stomach, contains cells/eznymes for digestion. depending on which part of stomach your in the name can change i.e. cardiac pits, fundic, pyloric.
what type of tissue lines gastric pits?
simple columnar epithelium (lumen in middle)
What type of cells do the gastric pits contain?
goblet cells, paretial cells (secrete and synthesize HCl
what type of folds are located in SI?
transverse folds called plicae circularis, allows for contraction and expansion. they become more prominant from proximal to distal.
what are the three parts of the SI from proximal to distal?
duodenum, jejunum and ilium.
what is unique about the jejunum in terms of villi?
they are LONG
what is unique about the ilium?
contain peyers patches or GALT (gastrointestinal associated lymphatic tissue), aggregates of 1000s of WBC, act as 1st line of defense.
intestinal glands also known as? located between what? lined with what type of tissue? what cells are located here?
crypts of lieberkuhn (invagination of mucosa)
villi
simple columnar epithelium
goblet cells and paneth cells (contain digestive enzymes)
what is the tissue that is below villi and located between intestinal glands?
laminia propria (part of mucosa) type of CT and is vascular.
where are brunners glands located in duodenum? what do they secrete? intestinal glands are located in which layer? lacteal is located in which layer (absorption occurs here)?
submucosa
mucous and serous (therefore enzymes and mucin)
lamina propria.
lamina propria
what surrounds plica circularis of SI?
villi
villi in jejunum are long, are they long anywhere else?
no short in duodenum and ilium.
duodenum in the SI is the first place of?
absorption!
peyers patches or GALT are located where?
ilium
what is a major difference between LI and SI?
SI has villi while LI does NOT!
which cells are located in LI?
goblet (secrete mucin) absorptive cells (little absorption done here, most done in SI, mainly water absorbed here) progenitor cells (regenerate epi lining) endocrine cells.
what tissue lines LI?
simple columnar epithelium
regeneration of the epithelium lining is done by? in the stomach what type of regeneration is used? in SI? is regeneration in epithelium cells continous?
stem cells
bidirectional flow (stem cells in middle, regenerate in both directions
in SI, unidirectional flow, stem cells located much deeper, they move upward and slough off.
YES
90-95% of malignant tumors in GI tract are from what source? tumors of large intestine are normally from?
epithelial cells glandular epithelium (called adenocarcinomas, 2nd most common cause of cancer deaths in US)
