Histology of Esophagus and stomach Flashcards
Four general layers o tube from lumen out?
mucosa (mucous membrane)
submucosa
muscularis externa
adventitia
_________________:
lining of internal passages
barrier between tissues & external environment
thin enough for absorption and/or secretion
supplemental mucus glands common in CT (for lubrication
Mucosa
3 layers of mucosa?
epithelium
lamina propria
muscularis mucosae
__________________:
loose CT underlying and supporting epithelium
contains: small vessels & lymphatics
nerves
mucosal glands may be present
varying amounts of lymphoid tissue
lamina propria of Mucosa in gut tube
_____________:
consists of 2 layers of smooth muscle (when present)
inner circular layer
outer longitudinal layer
3rd layer sometimes present (i.e. stomach)
luminal and longitudinal (or oblique)
permits localized movement of mucous membrane
Muscularis mucosae of the gut tube
_________________:
provides mobility for mucosa
contains:
plexuses of larger blood vessels lymphatics nerves parasympathetic ganglia (Meissners plexus) submucosal glands in some regions (esophagus and duodenum)
Submucosa of the gut tube
What is Meissners plexus? What layer is it in?
Parasympathetic ganglia
submucosa
What layer is Auerbach’s plexus found in?
Muscularis Externa
What does muscularis externa do?
maintains tonus in tube
propels luminal contents onward
How many layers of muscle are in the muscularis externa?
2 layers
inner circular layer
outer longitudinal layer
Is there adventitia in the esophagus?
No, only serosa
_________:
outermost coat of dense connective tissue
often blends with CT of surrounding area
Adventitia
____________:
hollow organs within or projecting into cavity covered with peritoneum
single layer of mesothelial cells
entire coat then called a serosa
large vessels and nerves found here
Serosa
What does epithelial lining of GI tract arise from?
endoderm
CT & smooth muscle are derived from?
mesoderm
How does the surface area of the GI tract change as you progress through it?
surface area (of lumen) increases
first by: invaginations (pits)
then by: invaginations (now called crypts)
evaginations (villi)
Characterize the musculature of the regions of the GI tract
upper third: mostly Sk. muscle
mid third: sk. and sm. muscle
lower third: mostly sm. muscle
What is unique about the muscle of the upper and mid esophagus?
It is involuntary skeletal muscle
What percentage of nutrients and water is absorbed in the esophagus?
Zero
What does the stomach absorb?
(5)
some salts
water
glucose
alcohol
drugs
Into what regions is the stomach divided into?
body
fundus
cardium
pylorus
The duodenum is retroperitoneal, how long is it? What ducts enter it?
10-12 inches
bile & pancreatic ducts enter
The jejunum is peritoneal, how long is it?
two-fifths (» 8ft)
The ileum is peritoneal, how long is it?
remaining three-fifths (»12ft)
________:
site of digestion/absorption
transport food from stomach to colon
secrete enzymes & certain hormones
divided into three parts
Small intestine
____________:
principal site of water resorption
dehydration of chyme
produces mucous secretion
some digestion
continued enzyme & bacterial activity
Fecal storage
What are the 6 portions of the large intestine? Identify which are peritoneal and retroperitoneal.
ascending - retroperitoneal
transverse - peritoneal
descending - retroperitoneal
sigmoid - retroperitoneal
__________________:
structure similar to colon, but:
muscularis externa of rectum is complete
mucosal folds bulge into lumen
numerous goblet cells
occasional enteroendocrine cells
connects to anal canal
Rectum
What is the density of goblet cells in the stomach?
0 goblet cells/cm2
________: connects rectum to anus
anal canal
___________:
epithelial change or demarcation from simple columnar to strat. squamous, wet.
divides the upper two thirds and lower third of the anal canal
Pectinate line (A.K.A - dentate line or mucocutaneous line)
_____________:
epithelium
stratified squamous non-cornified epithelium
very thick
rests on a relatively acellular CT
Esophageal mucosa
______________:
boundary provides better attachment for epithelium
peg =downward projections of epithelium
papillae = upward projections of connective tissue
Esophageal lamina propria
What does the lamina propria of the esophagus contain?
scattered lymphatic nodules
cardiac esophageal glands (mucous-secreting)
Esophageal muscularis mucosae (muscular layer) is well developed & may contain several layers of _______ and
some
smooth muscle
elastic fibers
Identify
Esophageal
Mucosa epithelium
lamina propria
muscularis mucosae
_______:
thrown into longitudinal folds
characteristic star-shaped outline to lumen (x-section)
folds allow lumen to dilate for passage of food bolus
esophageal glands scattered throughout submucosa
secrete mucous via ducts passing through mucosa
Esophageal submucosa
_________________:
smooth/skeletal ratio gradually increases
upper esophagus
mostly skeletal muscle
middle esophagus
skeletal & smooth muscle
lower esophagus
smooth muscle increases
finally, no skeletal muscle
Muscularis Externa
Is there adventitia in esophagus?
Yes, if I didn’t fix the other slide then disregard it. There is adventitia in esophagus. No serosa.
Dr. Choudry misspoke
Identify
Submucosa
muscularis externa
adventitia
_________:
transition from esophagus to stomach
sudden change from stratified squamous to simple columnar epithelium
cardioesophageal junction
What are the three histologic regions of the stomach?
Cardia
Fundus
Pylorus
________________:
largely serosa
mucosa very thick
epithelium
simple columnar epithelium
mucous-secreting cells (not goblet cells)
invaginates to line gastric pits
filled with many gastric glands
open to surface via gastric pits
gastric pits are tubular crevices
Stomach
____________:
occupies slit-like spaces
between gastric glands and pits
Lamina propria of the stomach
What is the muscularis mucosa like in the stomach? Where is it present?
Very thin
present at level of base of glands
_________:
extends into rugae
contains: blood and lymph vessels
peripheral nerves
CT cells
Submucosa of stomach
There are three layers of the muscularis externa in the stomach. What are they? What are their orientations?
inner layer - runs obliquely, incomplete
middle layer – circular orientation
continuous w/ inner m. layer of gut tube
thick at pylorus to form sphincter
outer layer - longitudinal orientation
continuous w/ outer m. layer of gut tube
_________: visceral peritoneum covers loose CT of the stomach continuous with greater & lesser mesenteries
Outer tunic - serosal layer
____________:
narrow, ring-shaped area around esophageal opening
gastric pits extend »1/4 to 1/2 depth of mucosa
cardiac gastric glands empty into base of each pit
Cardiac region of stomach
What are the two types of cells present in the cardiac region of the stomach?
surface mucous cell
on mucosal surface
lining gastric pits
undifferentiated cells
in base of pits
in neck of glands
_______:
largest area, proximal »2/3 of stomach
includes fundus and body
gastric pits extend down 1/4 to 1/3 of mucosa
each pit yields 3-7 gastric glands
gastric glands long & straight
Fundic region of the stomach
What iare the four cell types of the fundic region? Where are they found?
mucous neck cell
mainly found in neck of gland
parietal cells
some scattered cells in neck
more toward base
zymogenic chief cells
mainly found in base
enteroendocrine cells (argentaffin cells)
few in number, mainly in base
_______________:
distal 1/3 of stomach
gastric pits extend 1/2 depth of mucosa
pyloric glands are short, coiled
contain a mucous-secreting cell type
similar to the mucous neck cell
gastrin producing cells
common in pyloric glands
also in proximal part of duodenum
Pyloric region
How many goblet cells would we find in the intestine?
Lots
What type of cells secrete basic mucus?
None, until the intestine. They secrete acidic or neutral mucus only
What cell types secrete acidic mucus?
mucous neck cells
__________:
flattened basal nuclei
secretion granules and microvilli are apical
produce acidic mucus
differ structurally from surface mucous cells
mucous neck cells
________________:
large, round or triangular, cells with dark, central nuclei
cytoplasm stains pink to red with H & E
smooth ER prominent in cytoplasm
microvilli and intracellular canaliculi present
Parietal cells
What do parietal cells produce? What do these things do?
hydrochloric acid
activates acid-dependent enzymes
** intrinsic factor**
required for absorption of vitamin B12
vitamin B12 essential for hemopoiesis
Where do gastric enteroendocrine cells secrete their products?
into the lamina propria
________________:
resemble salivary serous cells in appearance
pale staining with H & E
oval nuclei and mitochondria are basal in location
apical, secretion granules (often poorly preserved)
microvilli are present
much rough-surfaced endoplasmic reticulum (ER)
produce enzymes found in gastric juice
pepsin (pepsinogen)
begins digestion of proteins (in acid medium)
lipase
initiates fat digestion
Chief cells
_______________:
present throughout entire GI tract
but not so numerous in gastric mucosa
(very common in small intestine)
in gastric glands
lie between chief cells and BM
not all seem to reach lumen
endocrine function
note polarization of secretion granules
Gastric enteroendocrine cells
What do gastric enteroendocrine cells synhtesize/secrete?
gastrin
somatostatin
vasoactive intestinal peptide (VIP)
serotonin (5-hydroxytryptamine)
glucose-dependent insulinotropic peptide (GIP)
[formerly gastric inhibitory peptide]
