Histology of Digestive System Flashcards
what are the associated or accessory digestive organs
tongue, teeth, salivary glands, pancreas, liver, gallbladder
what are the 4 main tissue layers of the digestive system from the lumen outward
- mucosa
- submucosa
- muscularis externa
- serosa/adventitia
the lamina propria is in what tissue layer of the digestive system ?
mucosal layer
what main tissue layer has an inner circular layer and an outer longitudinal layer ? what is the purpose of each ?
Muscularis externa
- inner circular - constricts lumen in peristalsis
- outer longitudinal - dilates lumen in peristalsis
where is the myenteric nerve plexus found, and what is its function
found b/w inner circular and outer longitudinal layers of the muscularis externa
-its the brain function of dig. system that controls peristalsis movements
what is the muscle tissue of the lumen in the proximal 1/3 of the esophagus ? middle 1/3 ? distal 1/3 ?
proximal 1/3 - skeletal muscle
middle - mixed
distal 1/3 - smooth muscle
the mesothelium can be found in what major layer of the digestive system
serosa
what type of epithelium is the mucosal lining in the esophagus ?
nonkeratinized stratified squamous epithelium
what layer would the esophageal glands (proper) be found in the GI system
submucosal layer throughout esophagus
what layer would esophageal cardiac glands be found ?
lamina propria of mucosal layer in distal esophagus
what is the function of the stomach
- physical breakdown
- chemical breakdown of lipids and proteins
- 10 % absorbtion
what type of epithelium is the mucosal lining of the stomach ?
simple collumnar epithelium
how many individual layers are w/in the muscularis externa in the esophagus ? stomach ?
esophagus - 2
stomach - 3
what are the 3 layers of the muscularis externa in the stomach from the lumen outward
inner oblique
middle circular
outer longitudinal
what anatomical region of the stomach would you find gastrin glands ? what do they do ?
fundus/body of the stomach in the mucosal layer
-secrete HCl and pepsinogen
how do secretions from glands w/in the mucosal layer reach the lumen ?
secretions travel through gastric pits and then into lumen
glands are located at base of pit
how can you tell the difference b/w cardiac glands and pyloric glands
both at base of gastric pits BUT
-gastric pits leading to pyloric glands are much longer
what are the folds w/in the stomach called
rugae
all glands w/in the stomach NEVER go past or extend into what tissue layer
muscularis externa
what are the 3 parts of the fundus of the stomach
isthmus, neck, and base
what special cells will you find in the isthmus of the (fundus) stomach
stem cells
what special cells will you find in the neck of the (fundus) stomach
mucous neck cells, parietal cells
what is the function of mucous surface and mucous neck cells
secrete mucous and adsorption
what is the function of parietal cells and where are they found
in the neck of the fundus of the stomach
-secrete HCl and intrinsic factor for absorption
what special cells will you find in the base of the (fundus) stomach
- chief cells
- G cells (enteroendocrine)
what is the function of chief cells and where can you find them
base of the fundus
- secrete pepsinogen (break down proteins)
- sectrete gastric lipase (break down fats)
what is the function of G cells and
base of the fundus
-secrete gastrin which stimulates parietal cells to secrete HCl
where does 90 percent of absoprtion in the body take place
small intestine
what are plicae circularis
small circular folds of the small intestine designed to increase surface area
-composed of a villus w/ multiple microvilli at surface
what does the small intestine digest
nucleic acids
the epithelial mucosal lining of the small intestine is what ?
simple collumnar epitheliu
what are crypts of Lieberkuhn and where are they found
intestinal glands found in small intestine at base b/w the villi in the mucosal layer or in mucosal layer of large int.
-Never extend into submucosa
where would you find more goblet cells the small intestine or large
large intestine cuz they are water absorbative cells
how many individual layers of the muscular externa is there in the small int.
2
- inner circular
- outer longitudinal
what are Brunner’s glands and where can they be found
glands in duodenum in the submucosal layer
-produce alkaline mucous to buffer stomach pH
what are paneth cells and where can they be found
-secrete lysozymes for digestion of bacterial cell walls
and regulate normal bacterial flora
-found in the crypt of lieberkuhn in mucosal layer of small int./
what are fingerlike projections of the small intestine designed for adsorption
villi
in the ileum of the small intestine, aggregations of lymph follicles in the lamina propria and submucosa are referred to as ?
Peyer’s patches
what are the specialized cells in ileum overlying the peyers patches and what is their purpose
M (microfold) cells
-present antigens
the absorptive cells in the small intestine are called
enterocytes
the adsorptive cells in the large intestine are called
colonocytes
what is the tenia coli and what part of GI tract is it found
band of smooth muscle in the muscularis externa layer of the large intestine
why are paneth cells not found in the large intestine
Because we need bacteria in the large intestines and paneth cells KILL bacteria
what is the function of the pancreas
98%- exocrine gland to secrete enzymes to surface
2 % - endocrine gland
where at in the distal part of the GI tract would you find a shift in the mucosal epithelial lining from simple collumnar epithelium to nonkeratinzed stratified squamous epithelium
recto-anal junction
where would you find islets of langerhans
pancreas
where does the liver recieve blood from
25 % - oxygenated blood from hepatic artery
75 % - deoxygenated nutrient-rich blood from hepatic portal vein
the liver is what shape anatomically
6 sided hepatic lobules
what are the type of cells that make bile
hepatocytes
what are the large phagocytic cells lining the sinusoids of the liver
Kupffer cells (type of macrophage)
explain the path of blood from when it enters the liver to final destination in the hear
enters then to liver sinusoids
- –> central vein —–> hepatic vein
- ——->inferior vena cava ———-> right atrium of heart
what is at each of the 6 corners of the liver
portal triad
