esophagus and stomach histo Flashcards
what are the 4 main layers of the gut tub
mucosa
submucosa
muscularis externa
adventitia
what are the key structures of the mucosa layer and related function
thin layer so provides barrier but also allows for absorption and secretion
also have supplementary mucous glands for lubrication
which layer of the gut tube is continous with the external environment
the mucosal layer
what are the three layers within the mucosa
epithelium with BM
lamina propria
muscularis mucosae
what is the role of the epithelial layer of the mucosa
primary is protection
secretion and absorption
describe the lamina propria layer of the mucosa
loose CT underying and supporting epithelium with small vessels and lymph
nerves
mucosal glands and varying amounts of lymph tissue
describe the structure of the muscularismucosae layer of the mucosa
inner circular layer of smooth m
outer longitudinal layer of smooth m
describe the 3rd variable layer within the muscularis mucosa of the mucosa layer
luminal and longitudinal can be found in stomach
what is the role of the smooth muscle layers in the muscularis mucosae
to allow localized movement of the mucous membrane
describe the structure of the submucosa layer
CT with elastic fibers with submucosal glands in the esophagus and duodenum reas
what is the role of the submucosa and what structures run init
provides motility
there are large blood vessels, lymph, nerves and parasympathetic ganglia (meissners)
describe the structure of the muscularis externa
thick inner circular and outer longitudinal layers of smooth muscle
both layers are spirally arranged
what structures around found between the layers within the muscularis externa
vascular and ANS plexi Parasympathetic ganglia (Auerbachs)
what is the function of the parasympathetic ganglia in the muscularis externa
propel luminal contents onward, maintains the tone
describe the outermost layer of the gut tube
the adventitia is a coat of dense CT that usually blends with surrounding areas
what is serosa
the coat of peritoneum with vessels and nerves that surround hollow organs in the cavity or ones projecting into the cavity
where do the epithelial linings of tracts arise from
endodern
where does the CT and smooth muscle derived from
mesoderm
how does the tract change as is progesses caudally
lumen widens surface area increase by invaginations (pits) that change into crypts and evaginations(villi) increase number of goblet cells basophilia increase lymphatic infiltration of CT increases
what is the function of the esophagus
connects pharynx to stomach
warms and cools food
what does the stomach absorb
some salts water glucose alcohol drugs
what are the four regions of the stomach
body funds cardium and pylorus
what are the functions of the SI
digest and absorb
secrete enzymes and hormones
what part of the SI is the duodenum
10-12 inches and is retroperitoneal
what amount of the SI is jejunum? ileum?
jejunum- 2/5 8 ft
ileum- 3/5 12 ft
what is the principal site for water resorption
large intestine, also dehydrates chyme
what is the main function of the large intestine
fecal storage
some digestion
produce mucous
what parts of the colon are peritonealized? retroperitoneal?
peritoneal- transverse and sigmoid
retroperitoneal- ascending and descending
how is the structure of the rectum different
muscularis externa is complete and the muscosal folds bulge into lumen
what are the parts of the anal canal
pectinate line which has a change from simple columnar epithelium to stratified squamous
is the anal canal retroperitoneal?
partially also extra peritoneal
what is the epithelium like of the esophagus
stratified squamous non cornfield thick with acellular CT
describe the lamina propria of the esophagus
there are pegs which are downward projections of epithelium and papillae which are upward projections of CT
have lymph nodules and cardiac esophageal glands
what do cardiac esophageal glands do
mucous secreting
describe the muscular is mucosae of esophagus
well developed with several layers of smooth m and some elastic fibers
describe the submucosa of the esophagus
longitudinal folds in a star shaped lumen with esophageal glands scattered in submucosa
describe the muscularis externa throughout esophagus
upper is mostly skel m
middle is skel and smooth m
lower is smooth and no skel m
describe the adventitia of the esophagus
blends with surrounding CT
no serosa
how does the epithelium change at the cardioesophageal junction
stratified squamous to simple columnar
what is considered the histologic fundus of the stomach
the body and fundus
describe the epithelium layer of the stomach
simple columnar with mucous secreting cells and invaginations of gastric pits with glands
are goblet cells present in the stomach
no
describe the lamina propria of the stomach
occupies slit like spaces between gastric glands and pits
describe the muscularis mucosa layer of the stomach
at the base of the glands
describe the submucosa layer of the stomach
extends into rugae with blood and lymph and peripheral nn and CT cells
describe the muscularis externa of stomach
inner layer- imcomplete and oblique
middle layer- circular and continous with inner m layer of gut
outer layer- longitudinal which is continuous with outer layer of gut
what layer of muscularis externa thickens to form pyloric sphincter
middle
What is the outer tunic of the stomach
the serosal layer of visceral peritoneum that covers loose CT and continuous with the greater and lesser mesenteries
What glands are present in the cardiac region of stomach
cardiac gastric glands
what cells are found in the cardiac region of stomach
surface mucous cells lining the gastric pits
undifferentiated cells in the base of pits and neck of glands
how often to glandular cells turn over? surface?
surface are like 4-5 days
glandular take longer
how big are gastric pits in the fundus region
1/4 -1/3 of mucosa with 3-7 glands in each pit
What cell types are present in the fundic region
mucous neck cell
parietal cell (near base of gland)
zymogenic chief cells (in base of gland)
enteroendocrine cell (mainly at base)
how deepa re the gastric pits in the pyloric region of stomach
1/2 mucosa
describe the pyloric glands in the pyloric region
have mucous secretin cells and gastrin producing cells
describe characteristics of surface mucous cells and role
columnar cells that line the gastric pits and appear empty because of mucous droplets and the function to netralize mucus
no goblet!!
describe mucus neck cell characteristics
flattened basal nuclei that secrete granules and the microvilli are apical
these produce acidic mucus and differ from surface cells
describe parietal cells
large round or triangular cells iwth dark central nuclei
cytoplasm stains pink to red
smooth ER has lots of cytoplasm
there are microvilli and intracellular canaliculi
what do parietal cells produce
hydrochloric acid that activates enzymes
intrinsic factor that is required for absorption of vit B12
what is vit b12 essential for
hemopoiesis
describe chief cells
pale stain with oval nuclei and mitochondria are basal in location apical secretion granules have microvili rough ER produce enzymes found in gastric juice
what enzymes do chief cells produce
pepsin (protein digestion)
lipase (fat digestion)
what cell type is very common in SI
gastric enteroendocrine
what is the function of gastric enteroendocrine cells
sythesize and store hormones gastrin somatostatin vasoactive intestinal peptide serotonin glucose-dependent insulinotropic peptide(gastric inhibitory peptide)
describe the order of gastric cell types from sruface of lumen to deeper layer
surface mucous cell mucous neck cell parietal cell chief cell enteroendocrine cell muscularis mucosa
