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