Histology of Esophagus and Stomach

Question 1

What does the mucosa consist of in the GI tract?

Answer 1

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.

Question 2

What makes up rugae and plicae?

Answer 2

Mucosa and submucosa extend into lumen

Question 3

What makes up villi in GI?

Answer 3

mucosae

Question 4

What does the submucosa consists of?

Answer 4

dense irregular CT
Large blood vessels and nerves
lymphatics
glands in esophagus and duodenum

Question 5

What does the muscularis externa consist of?

Answer 5

2 layers of Sm m.
Circular layer - inner layer; reduces lumen and propels food
Longitudinal layer - outer; shortens tube

Question 6

Describe adventitia

Answer 6

outside the peritoneal cavity
binds to body wall
loose CT
blood vessels and nerves

Question 7

Describe serosa

Answer 7

within peritoneal cavity
loose ct
simple squamous
blood vessels, nerves, adipose tissue

Question 8

What intrinsic nervous system is in the submucosa?

Answer 8

meissners plexus - secretory activity of mucosal/submucosal glands

Question 9

What intrinsic nervous system is between the inner and outer layers of muscularis externa?

Answer 9

myenteric (auerbach): motility

Question 10

Where is the upper esophageal sphincter (UES)? What is its function?

Answer 10

near cricopharyngeus muscle

Anatomically defined sphincter that participates in the initiation of swallowing

Question 11

Where is the LES? What is its function?

Answer 11

Anterior to gastroesophageal junction

Functionally defined sphincter that prevents reflux, regurgitation of stomach contents

Question 12

Describe the mucosa of the esophagus

Answer 12

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.

Question 13

What is GERD?

Answer 13

change in epithelium in esophagus to columnar
Chronic esophagitis/ulceration
Dysphagia
Fibrosis a/o esophageal strictures

Question 14

What is Barrett’s esophagus?

Answer 14

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

Question 15

What are the motility regions of the stomach?

Answer 15

Orad - relaxed during swallowing and the initial holding area of the proximal stomach
Caudad area - regulation of gastric emptying; makes sure mixing occurs

Question 16

Describe mucous cells

Answer 16

neck - opening of gland into pit
surface - line pit
secrete mucin to protect
traps bicarb
neutralizes microenvironment 
mucous layer - holds water

Question 17

Describe parietal/oxyntic cells

Answer 17

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

Question 18

What is autoimmune gastritis?

Answer 18

autoantibodies to H/K ATPase and intrinsic factor ; destruction of parietal cells
Decrease HCL and vit B12 deficiency -> pernicious anemia

Question 19

What can H. pylori in the stomach cause?

Answer 19

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

Question 20

Describe chief/peptic cells

Answer 20

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

Question 21

What is pepsinogen?

Answer 21

zymogen of pepsin which digest most protein

Question 22

What is the function of gastroentero-endocrine cells?

Answer 22

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)

Question 23

What is secretin released by? what does it stimulate?

Answer 23

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

Question 24

What is gastrin released by? what does it stimulate?

Answer 24

Produced by G cells in pyloric antrum
stimulate production of HCL by parietal cells
Activate CCK to stimulate gallbladder contraction

Question 25

What is CCK released by? what does it stimulate?

Answer 25

produced by duodenum and released when protein and fat rich chyme enters duodenum thru sphincter of Oddi
stimulates gallbladder contraction

Question 26

What is GIP released by? what does it stimulate?

Answer 26

Glucose-dependent insulinotrophic peptide
produced in duodenum when glucose is present in S.I.
Stimulates insulin release

Question 27

What is Motilin released by? what does it stimulate?

Answer 27

Released cyclically every 90 min. during fasting from upper S.I.
stimulates motility and fundus contraction to remove content from stomach
Neuronally controlled

Question 28

What is Ghrelin released by? what does it stimulate?

Answer 28

Produced by fundus of stomach
binds to receptor present in GH-secreting cells of anterior hypophysis
Increase during fasting triggering hunger thru hypothalamic feeding centers

Question 29

Describe lamina propria of stomach

Answer 29

reticular fibers and collagen fibers predominate

Fibroblasts, lymphocytes, mast cells, eosinophils and a few plasma cells

Question 30

Describe submucosa of stomach

Answer 30

dense irregular CT
Abundant collagenous and elastic fibers
Vessels, lymphatics
meissners plexus

Question 31

Describe muscularis externis of stomach

Answer 31

3 poorly defined layers of sm. m in circular, oblique and longitudinal directions
Circular layer thickens to form annular pyloric sphincter

Question 32

What is hypertorphic pyloric stenosis?

Answer 32

occurs in kids
children are puking non bilius vomit
food cant move from stoach to duodenum