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Digestive System (Microanatomy) (small intestine (goblet cells, microfold…
Digestive System (Microanatomy)
GI tract (mouth to south)
enteric nervous system
submucosal plexus
(Meissner's plexus)
function:
regulates secretion
myenteric plexus
(Auerbach's plexus)
function:
regulates movement
shared histological features
submucosa
muscularis externa
mucosa
epithelium
(which have microvili)
lamina propria
= loose connective tissue
muscularis mucosae
(contraction helps move glandular secrections)
serosa (visceral peritoneum) = adventitia
liver
structure of a liver lobule
six
triad
areas (at each of the 6 vertices of the lobule) =
1 portal vein, 1 hepatic artery, 1 bile duct
cells:
hepatocytes
(make bile),
Kupffer
(macrophages)
central vein (outflow tract)
pancreas
exocrine
: Islet of Langerhans (makes insulin and glucagon which it secretes into blood)
endocrine
: acinar cells (make digestive enzymes)
gallbladder
function:
stores and concentrates bile
lots of mitochondria
microvilli
salivary glands
submandibular gland
(medium)
secretion:
alpha-amylase + lysozyme (mix)
H&E stain:
medium
subllingual gland
(smallest)
secretion:
mostly mucus
H&E stain:
light
parotid gland
(largest)
secretion:
alpha-amylase (mostly protein)
H&E stain:
dark
stomach
gastro-esophageal junction:
esophagus has stratified squamous epithelium vs the stomach that has simple columnar that is covered in an alkaline mucus
structure of a gastric gland + pit
mucous cells:
alkaline mucus
mucus cells of the neck of the gland
: less alkaline mucus
parietal cells:
secrete H+ and Cl- and
intrinsic factor
, look like fried eggs
smooth muscle cells
gastrin:
produces gastrin, stimulate parietal cells (via histamine), stimulates chief cells to produce pepsinogen, stimulate smooth muscle of the gastric gland to contract
chief cells:
secrete proenzyme, contain zymogen granules that contain pepsinogen (eosinophilic)
duodenum
main location for digestive regulation
primary functions
receive:
chyme (low pH) from stomach, digestive enzymes from pancreas
neutralize:
acid from stomach using bicarb. (
HCO3-
) from Brunner's glands (local) and the pancreas
regulate:
GI tract activity by the release of hormones
small intestine
goblet cells
microfold cell
enter-endocrine cell
paneth cell