Histology of Esophagus and Stomach Flashcards
What does the mucosa consist of in the GI tract?
A lining of epithelium with mucosal and submucosal glands and ducts
Underlying lamina propria consisting of vascularized loose CT and immune system
Thin double layer of Sm m.
What makes up rugae and plicae?
Mucosa and submucosa extend into lumen
What makes up villi in GI?
mucosae
What does the submucosa consists of?
dense irregular CT
Large blood vessels and nerves
lymphatics
glands in esophagus and duodenum
What does the muscularis externa consist of?
2 layers of Sm m.
Circular layer - inner layer; reduces lumen and propels food
Longitudinal layer - outer; shortens tube
Describe adventitia
outside the peritoneal cavity
binds to body wall
loose CT
blood vessels and nerves
Describe serosa
within peritoneal cavity
loose ct
simple squamous
blood vessels, nerves, adipose tissue
What intrinsic nervous system is in the submucosa?
meissners plexus - secretory activity of mucosal/submucosal glands
What intrinsic nervous system is between the inner and outer layers of muscularis externa?
myenteric (auerbach): motility
Where is the upper esophageal sphincter (UES)? What is its function?
near cricopharyngeus muscle
Anatomically defined sphincter that participates in the initiation of swallowing
Where is the LES? What is its function?
Anterior to gastroesophageal junction
Functionally defined sphincter that prevents reflux, regurgitation of stomach contents
Describe the mucosa of the esophagus
epithelium: non keratinized stratified squamous (non absorptive)
Lamina propria: thin elastic C, limited # of superficial mucosal glands
Muscularis mucosae: upper - thin elastic; lower - sm m.
What is GERD?
change in epithelium in esophagus to columnar
Chronic esophagitis/ulceration
Dysphagia
Fibrosis a/o esophageal strictures
What is Barrett’s esophagus?
Abnormal columnar epithelium replaces stratified squamous epithelium (metaplasia) in the distal esophagus
Most severe consequence = chronic GERD and predisposed to adenocarcinoma
Mean age for development = 40
Dx = 63 yo
What are the motility regions of the stomach?
Orad - relaxed during swallowing and the initial holding area of the proximal stomach
Caudad area - regulation of gastric emptying; makes sure mixing occurs
Describe mucous cells
neck - opening of gland into pit surface - line pit secrete mucin to protect traps bicarb neutralizes microenvironment mucous layer - holds water
Describe parietal/oxyntic cells
Make HCL, intrinsic factor (helps absorb Vit B12)
Carbonic anhydrase and H/K ATPase in microvilli
Stimulated by ACh and gastrin produced by enteroendocrine cells of pyloric antrum
What is autoimmune gastritis?
autoantibodies to H/K ATPase and intrinsic factor ; destruction of parietal cells
Decrease HCL and vit B12 deficiency -> pernicious anemia
What can H. pylori in the stomach cause?
survive and replicates in gastric lumen and associated with peptic ulcers and adenocarcinoma of stomach
20% of pop. by age 20
60% by age 60
Describe chief/peptic cells
predominate in lower 1/3 of gastric glands
not present in cardiac glands and pyloiric antrum
Stimulation of feeding and ACh causes release of pepsinogen
What is pepsinogen?
zymogen of pepsin which digest most protein
What is the function of gastroentero-endocrine cells?
ACh and gastrin produced here: act to increase parietal cell activity
make hormones of DNES to regulate water, electrolyte metabolism, enzyme secretion, motility, stimulate release of other peptide hormones
DNES (diffuse neuroendocrine system)
What is secretin released by? what does it stimulate?
released by duodenal glands of lieberkuhn
stimulate pancreatic and duodenal glands (brunner’s) bicarb and fluid release to control gastric acid secretion, moderate pH
Stimulates chief cells; inhibit gastrin release
What is gastrin released by? what does it stimulate?
Produced by G cells in pyloric antrum
stimulate production of HCL by parietal cells
Activate CCK to stimulate gallbladder contraction
