Week 20 (upper GI tract anatomy part 2) Flashcards
how long is the oesophagus
25 cm long
at what cerebral levels does the oesophagus begin and end
C2->T10
within the epithelium of the oesophagus what is the epithelial structure of the mucosa
stratified squamous epithelium
in the mucosa what cells help in immunity in the GI tract
langherhans cells
within the mucosa, what glands help the lamina propria in lubricating boluses of food
cardiac glands
cardiac glands in what layer help lubricate boluses of food (with thick mucus)
lamina propria
why is the lamina propria fibroelastic
needs to resist abrasive forces
what gland is situated in the submucosa in the epithelium of the oesophagus
oesophageal glands
within the oesophageal epithelium why is the muscularis externa unique
the upper 1/3rd contains skeletal muscle
how is the muscularis externa in the oesophagus structured
upper 1/3rd skeletal muscle
middle 1/3rd skeletal smooth muscle
lower 1/3rd smooth muscle
the muscularis externa contributes to what movement of boluses
peristaltic
the muscularis externa contributes to peristaltic movement of boluses of food from where to where
oropharynx to stomach
reflux of a bolus is prevented by what
sphincters
facilitating peristalsis (pinching motion) occurs in what direction
from head down to anus
what is the role of the upper and lower sphincters
to prevent accidental aspiration and prevent reflux of boluses
why does the lower sphincter close after bolus of food passes
closes to keep the acid in stomach
what happens if there is an issue with the lower sphincter (not closing properly)
leads to metaplasia of stratified epithelium
->adenocarcinoma
how can barrett’s oesophagus be classified
metaplasia of oesophageal epithelium in lower portion of the oesophagus
in barrett’s epithelium how does the epithelial structure change
stratified columnar epithelium -> simple columnar epithelium
in Barrett’s oesophagus premalignant changes can lead to development of what
adenocarcinoma
how is the anatomy of the stomach divided
4 regions
fundus
cardia
body pyloric (antrum and canal)
what is the vertebral level the stomach reaches
T10 - L1
the stomach can be thrown into folds by what
muscularis externa
what sphincter separates the stomach from the small intestine
pyloric sphincter
what acid is secreted from the cells in the stomach
hydrochloric acid
within the epithelium of the stomach the mucosa can be thrown into folds called what
rugae
gastric pits are present in what layer of the epithelium
mucosa
the gastric pits in the stomach are composed how of many different cell types
5
what are the 5 different cell types that compose the gastric pits in the stomach
superficial epithelial cell
mucous neck cell
stem/progenitor cell
parietal cell
chief cell
enteroendocrine cell
what are the 3 functions of the gastric pits
secrete:
HCl
Mucus
Bicarbonate (HCO3-)
in the stomach, what does the cardia primarily secrete
mucus
in the stomach, what does the fundus and the body primarily secrete
mucus, HCl, and pepsinogen
in the stomach, what does the pylorus primarily secrete
gastrin and somatostatin
what do superficial epithelial cells secrete
visible mucus and bicarbonate
in the stomach epithelium, what do the superficial epithelial cells do
retain secreted bicarbonate at the apical surface of the stomach epithelium to prevent autodigestion
what allows the mucus to stick to the epithelium of the stomach and allows the bicarbonate to stick there
thick and sticky
what is the role of bicarbonate in the stomach
acts as a buffer in the stomach so the stomach doesnt digest itself
where are mucous neck cells located
in the “neck” of the gastric pit
what do mucous neck cells secerete
soluble mucous
what is the role of the soluble mucus that mucous neck cells secrete
lubricates and reduces friction
mucous neck cells secrete a more soluble viscous mucus that help with digesting what kind of food
rough food such as salt and vinegar crisps
what is the purpose of stem/progenitor cells
dont secrete anything but can proliferate to replace all cell types in epithelium of stomach
how often do stem/progenitor cells proliferate to replace new cells
every couple of days
what do parietal cells secrete
HCl and intrinsic factor
what are the 2 states of parietal cells
resting and active
how does HCl worl
steralises food and aids in digestion
what is the structure of parietal cells
atypical and pyramidal
when would a parietal cell be in a resting state
between meals
when would a parietal cell be active
once you have had a meal
what happens when a parietal cell is in its active state
villi like structures form along the apical membrane and increases the Surface area of the cells
what are chief cells responsible for secreting
pespsinogen and lipase
what membrane domain are chief cells located on
apical membrane
what secretory vesicles are chief cells containing
zg secretory vesicles
in chief cells, what is the role of pepsinogen
breaksdown peptides and proteins
in chief cells, what is the role of lipase
breakdown of lipids or fats
what are some characteristics of the submucosa in the stomach
dense and irregular and rich with vascular and lymphatic supply
how many layers in the muscularis externa in the epithelium of the stomach made up of
3
what are the 3 layers that make up the muscularis externa in the epithelium of the stomach
innermost oblique layer
middle circular layer
outer longitudinal layer
what are characteristics of the serosa in the epithelium of the stomach
very thin, simple squamous epithelium
capacity to secrete lubricating factors that help churn the stomach
why is there rich vascular supply and lymphatic supply in the submucosa in the epithelium of the stomach
contraction of muscle which coordinates the ability to churn
immune cells to deal with threats
what is the product of surface epithelial cells
visible mucus and bicarbonate
what is the product of mucous neck cells
soluble mucous
what is the product of parietal cells
HCL and intrinsic factor
what is the product of chief cells
pepsinogen and lipase
what is the prodcut of D cells
somatostatin
what is the product of G cells
Gastrin
what causes gastric ulcers
infection with H. Pylori
what is a gastric ulcer
disruption of gastric epithelium and inflammatory changes lead to ulceration
what can cause gastric ulcers
overuse of NSAID’s
(ibuprofen) and anti-inflammatory drugs
