GI II Flashcards by Jassie McGovern

What is the 4 basic layers to the wall of GI tube?

1) mucosa
2) submucosa
3) muscularis externa
4) serous/adventitia

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What three components constitutes mucosa?

1) epithelium resting on basal lamina
2) lamina propria
3) muscularis mucosae

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Most of the GI tract will have this type of epithelium

simple columnar

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Which 3 portions of the GI tract will have a different type of epithelium? What type of epithelium is it?

1) proximal GI tube (esophagus)
2) distal end of GI tube
3) distal anal canal
stratified squamou

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What’s in lamina propria (4)?

1) connective tissue
2) glands
3) blood vessels
4) lymphatic tissue

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What are the two layers of smooth muscles in muscualris mucosae?

1) inner circular

2) outer longitudinal

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What is the purpose of the two layer of smooth muscles in muscularis mucosae?

when contracting, they wrinkle the mucosa, increasing surface area, which facilitates absorption of nutrients and secretion

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True or false. Glands can be found in the submucosa.

True. glands can be found in this layer in the esophagus and duodenum (all others are in lamina propria)

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What type of connective tissue is present in the submucosal layer?

dense irregular

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Besides connective tissue, what else can be found in the submucosa?

1) glands (in esophagus and duodenum)
2) blood and lymphatic vessels
3) submucosal or Meissner’s plexus

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How many layers of smooth muscles are in muscularis externa?

two: inner circular and outer longitudinal

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What’s the function of muscularis externa?

contraction result in peristasis

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Myenteric (Auerbach’s) plexus is located in which layer?

muscularis externa

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What’s the difference between adventitia and serosa?

serosa has an extra layer (mesothelium) located external to muscularis externa. adventitia has connective tissue layer only

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What kind of nerve fibers are found in submucosal (Meissner’s) plexus?

1) parasympathetic postganglionic neurons

2) sympathetic postganglionic fibers

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What’s the function of Meissner’s plexus (3)?

regulate glandular activity, blood flow, muscualris mucosae and is sensory

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What kind of nerve fibers are found in myenteric (Auerbach’s) plexus?

1) parasympathetic postganglionic neurons

2) sympathetic postganglionic fibers

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What’s the function of Auerbach’s plexus?

regulate peristalsis

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What does achalasia affect?

esophagus

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What is Hirschsprung’s disease?

congenital megacolon

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What type of epithelium is present in esophagus?

stratified squamous, nonkeratinized

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What distinctive feature is found in the lamina propria of the esophagus?

cardiac esophageal glands

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Mucularis mucosae of the esophagus is better developed in which section?

distal portion of esophagus

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What type of glands are found in submucosa of esophagus?

esophageal glands proper (seromucous)

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The upper 5% of the esophagus is comprised of which type of muscle?

skeletal

Upper esophagus is comprised of which type of muscle?

skeletal and smooth

The lower 50% or greater of esophagus is comprised of which type of muscle?

smooth

Which part of the esophagus has adventitia?

thoracic esophagus

Which part of the esophagus has serosa?

abdominal esophagus

To confirm the diagnosis of Barrett's esophagus, what must be seen in a micrograph?

metaplastic columnar epithelium with goblet cells

Which staining technique is used for Barrett's?

PAS/Alcian blue stains

What structures do PAS/Alcian blue stain differentiate?

regular mucous-producing cells and goblet cells

What type of epithelium does the stomach have?

simple columnar

Why would you find simple columnar epithelium in the esophagus, such as Barrett's?

defense mechanism from the body to protect the lining of the esophagus from acid reflux. unfortunately, there is risk for progression to adenocarcinoma

Which cancer staging describes invasion within the mucosa?

HGD (high-grade dysplasia) and T1 intramucosa

Which cancer staging describes invasion of submucosa?

T1 submucosal

Which cancer staging describes invasion of muscularis externa?

Which cancer staging describes invasion of all layers of the GI wall?

Which cancer staging describes invasion of nearby organ?

How would cancer cells spread in the lymphatic vessels of the esophagus?

cranially or caudally because the vessels are arranged longitudinally

Cancer cells are found in the lymph nodes of the neck, you suspect it could be metastasis of esophageal cancer, where in the esophagus will these cells most likely originate from?

upper 2/3 of the esophagus

Cancer cells from lower 1/3 of the esophagus can metastasize to which regional lymph nodes?

cardiac

What are the four regions of the stomach?

1) cardia 2) fundus 3) body 4) pylorus

Folds of mucosa and submucosa that allows for stomach to extend and flatten

rugae

Describe the lamina propria of the stomach

they have invaginations of the epithelium that are packed with glands. these invaginations form gastric pits where the glands empty into

What type of epithelium does the stomach have?

simple columnar

Which layer are lymphatics located in the stomach?

much more prominent in the submucosa than lamina propria

Certain regions of the stomach has 3 muscle layers, what is this third muscle layer?

inner oblique

The pylorus has a thickened smooth muscle layer, which layer is it?

middle circular layer

There are three regions of glands in the stomach, what are they?

1) cardiac glands (in the cardiac region) 2) pyloric glands (in the pylorus region) 3) gastric glands (anywhere in between)

The fundus and body of the stomach have gastric glands that are divided into three regions, what are they?

1) isthmus 2) neck 3) fundus (base)

Which of the three regions of gastric glands are the most superior?

isthmus

What types of cells are found in the isthmus region?

stem cells for any cell type found in the epithelium of the stomach

Which gastric gland region is below the isthmus?

neck

What cell type is most dominant in neck region?

parietal cells

What's the function of parietal cells?

secrete HCl and intrinsic factor

What is intrinsic factor important for?

Absorption of vitamin B12

Which cell type is the most predominant in the fundus region?

chief cells

What's the function of chief cells?

secrete pepsinogen

True or False. Parietal cells and chief cells are found in both neck and fundus region of gastric glands.

True

What other cell type can be found in the fundus region?

various hormone secreting cells = enteroendocrine cells

Cardiac glands have an abundant of which type of glandular cell?

mucous cells

Pyloric glands have special type of cell known as G cells, what is their function?

secretion of the hormone gastrin

Which of the three glandular regions have the most diverse population of cell types?

gastric glands

Does the stomach have goblet cells?

No, they have mucous secreting cells

What are the seven defense mechanisms that exist to defend against assault by pepsin and acid?

1) presence of unstirred layer of mucus 2) surface epithelial cells secreting mucus and bicarbonate and other factors 3) cell renewal 4) alkaline tide 5) microcirculation 6) sensory nerves 7) prostaglandins

Mucus is acidic or alkaline?

alkaline. it contains bicarbonate that helps protect the stomach lining from the acidic environment

What is the alkaline tide?

blood is more alkaline and the microciculation, the epithelial cells will pick up the increased bicarbonate ions

An erosion is damage to which stomach wall layer?

confined to mucosa

An ulcer is damage to which stomach wall layer?

the damage has penetrated through the mucosa and it's now in submucosa

What three structures in the small intestines increase surface area for absorption?

1) plicae circulares 2) intestinal villi 3) microvilli

Permanent folds of mucosa and submucosa. Increases surface area 3-fold

plicae circulares

Fold of mucosa. Increases surface area 10-fold

intestinal villi

Located along the apical domain of columnar cell. Increases surface area 20-fold

microvilli

What are the four signature histologic features of gluten enteropathy (celiac sprue)?

1) enterocytes are disarrayed 2) villus atrophy 3) crypt (intestinal gland) hyperplasia 4) inflammation of lamina propria

What causes Zollinger-Ellison syndrome?

tumor of gastrin-secreting cells

What is the gastrinoma triangle?

Tumors can arise in any of these areas: 1) junction of cystic and common hepatic ducts 2) junction of pancreatic head and neck 3) junction of parts 2 and 3 of duodenum