Stomach and Esophagus Flashcards
How many layers of the esophagus? What are they from outermost to innermost?
4 layers: Serosa/adventitia muscalaris externalis submucosa mucosa
What are the three layers of the esophageal mucosa?
- epithelium
- lamina propria
- muscularis mucosa
What are the functions of the esophageal mucosa epithelium?
protective, absorptive, secretory –> may form glands –> often in folds/villi to increase SA
What is the esophageal mucosa epithelium composed of?
nonkeratinized stratified squamous/columnar -> undergoes continuous renewal
The upper third of the espohagus is composed of what muscle fibers?
skeletal muscle fibers, but undergo involuntary contractions
The middle third of the espohagus is composed of what muscle fibers?
mixture of smooth and skeletal muscle
The lower third of the espohagus is composed of what muscle fibers?
only smooth muscle
What does the lamina propria of the esophageal mucosa have?
glands, lymphatic tissue, and macrophages
What is the muscularis mucosa?
- outer layer of the esophageal mucosa
What is the function of the muscularis mucosa
promotes movement of mucosa
What is the muscularis mucosa composed of?
2 thin layers of smooth muscle
what forms the submucosa?
dense connective tissue made from collagenous and elastic fibers
–thrown into folds
What is another name for the submucosal plexus?
What is another name for the meissner’s corpuscle?
Where would we find exocrine glands in the esophagus?
submucosa
Where do we find meissner’s plexus?
at the junction between submucosa and inner circular layer of the muscularis externa
Where do we find superficial glands? what else are the called?
superficial glands = cardiac glands
- found only in the lamina propria of the proximal and distal esophagus
What do esophageal cardiac glands do?
provide a thin, highly viscous film of mucous to lubricate the esophagus
What are the deeper glands of the esophagus?
aka esophageal glands = submucosal glands
- secrete acidic mucin
- located in the submucosa –> penetrate the muscularis mucosa to reach the lumen of the esophagus
What are two layers of the muscularis externa?
inner circularly arranged layer
outer longitudianally arranged layer
they may be smooth or skeletal
Where is the myenteric plexus located? another name for it?
aka auerbach’s plexus
-between the two layers of the muscularis mucosa
What is serosa?
loose connective tissue that is covered by a simple squamous mesothelium
What is adventitia?
connective tissue merged together that supports and protects
Where is the esophagus covered by serosa? and adventitia?
esophagus in the peritoneal cavity is covered by serosa, the rest is covered by adventitia
What is Barrett’s esophagus?
a response to injury –conversion from stratified squamous to simple columnar –> causes inflammation, possible cause of cancer, especially if too much acid reflux
What are the three functions of the stomach?
- reservoir of chyme
- secretion of HCl
- source of intrinsic factor
- short term storage facility for food
What are the four layers of the stomach?
mucosa, submucosa, muscularis externa, serosa/adventitia
What are the four regions of the stomach?
cardia, fundus, body, pylorus
What are rugae?
folds that increase the SA in the stomach - flatten as the stomach expands
What type of epithelium cellular layer does the stomach have?
tall, simple columnar - replaced every 4-7 days
What types of cells is line the stomach? what do they secrete?
mucus cells - secrete mucin, serves as a protective coating
What are gastric glands?
invaginations of the surface epithelium
- found in the body and fundus
- largest and most numerous
- make up 75% of the mucosa
What are the three types of glands found in the stomach?
cardiac glands - found at the junction of the esophagus and stomach. secretions make up less than 10% of total mucosa
gastric glands - in the fundus, pylorus, and body - secrete 75% of mucosa
pyloric glands - 15% of mucosa secretions, found in the pylorus closest to duodenum of the stomach
Where exactly do we find the gastric glands?
lamina propria of the mucosa
What are the three parts of the gastric glands?
isthmus, neck, and body
What types of cells are located in the neck region of the gastric/fundic glands?
mucous neck cells and parietal cells
What types of cells are located in the body of the gastric/fundic glands?
upper part of the body: parietal and chief cells
lower part of the body: mostly chief cells
What types of cells are mostly found in the cardiac and fundic glands?
mucus-secreting cells
Tell me about the cardiac glands in the stomach.
- short branched tubular glands with short gastric pits
- centered around the esophageal orifice
- produce a mucus secretion that is 10% of the stomach’s total secretion
What are the three types of gastric glands?
cardiac, fundic, pyloric
What are fundic glands?
= main gastric gland
99% of all stomach glands
-main acid (HCl) and enzymatic producing gland
What are the 6 different cell types located in the fundic glands?
- surface epithelial cells
- undifferentiated/stem cell
- chief cells
- parietal cells
- mucous neck cells
- enteroendocrine cells
Describe the surface epithelial cells of the fundic glands.
tall columnar cells that produce a basic mucus for protection
Describe the undifferentiated/stem cell of the fundic gland.
mitotically active cells that can replace cells lost via apoptosis
- located in the isthmus and neck of the gland
Describe the chief cells of the fundic gland.
localized at the base of the fundic gland and produce pepsinogen and lipase enzymes
Describe the parietal cells of the fundic gland.
source of HCL and intrinsic factor – located mainly in the neck
- numerous mitochondria and cell membrane invaginations forming canaliculi from tubulovesicles
Tell me about pyloric glands
- mucus producing glands with deep gastric pits –> similar to cardiac glands, but with deeper pits
- some enteroendocrine cells present
What are the three layers of the muscularis externa of the stomach?
- outer longitudinal
- middle circular
- inner oblique
Where is the myenteric plexus located in the stomach wall?
between the middle circular and outer longitudinal layer of the muscularis externa
What is the function of the muscularis externa of the stomach?
provides a means of peristalsis - mixing action of the stomach
