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Histology > GI Epithelium > Flashcards

GI Epithelium Flashcards

0
Q

What type of epithelium is found on the lip?

A

Stratified, squamous, keratinized epithelia with HAIR FOLLICLES.

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1
Q

What structures are only found on thin skin?

A

Hair follicles

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2
Q

What is the name of the transitional region between the thin epithelium between oral mucosa and the skin? What does it lack and how is it kept moist?

A

The red VERMILLION ZONE…lacks salivary or sweat glands and is kept moist with saliva from the tongue.

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3
Q

What is the best way to identify the transition between epithelium of vermillion and oral mucosa? What is the name for the type of epithelium found in the oral mucosa?

A

Transition from keratinized to nonkeratinized. Oral mucosa is stratified, squamous, NONKERATINIZED epithelium. It is called WET EPITHELIUM because it lines a cavity.

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4
Q

What structure(s) at the core of the lips allows for ingestion and speech?

A

Striated skeletal muscle.

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5
Q

What structure separates the papillar portion of the tongue from the root?

A

A V-shaped groove called the SULCUS TERMINALIS <–p.292

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6
Q

List and describe the four types of lingual papillae –> 13.5, 13.6 Wilson

A
  1. ) Filiform papillae: Pointed to provide friction to help move food during chewing. KERATINIZED STRATIFIED SQUAMOUS EPITHELIUM. No taste buds.
  2. ) Foliate papillae: Ridge-like, on the sides of tongue. Best developed in young children.
  3. ) Fungiform papillae: Scattered across the dorsal surface. Resemble mushrooms on cross-section view. UNKERATINIZED STRATIFIED SQUAMOUS EPITHELIA. Contain taste buds.
  4. ) Vallate papillae: Present in the V-shaped line near terminal sulcus.
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7
Q

What are the different orientations of the muscle in the tongue?

A

Oblique, cirumferential, longitudinal.

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8
Q

What are the most numerous type of papillae on the tongue? Which are the largest?

A

Filiform = most numerous. Valate = largest.

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9
Q

On which papillae are taste buds found?

A

vallate, fungiform, and foliate. NOT KERATINIZED FILIFORM. p.294

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10
Q

What is the difference in epithelia between the oral cavity and esophageal mucosa?

A

No difference. Esophageal mucosa the same stratified squamous, nonkeratinized epithelium, with the exception that it has BASAL STEM CELLS.

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11
Q

What parts of the GI tract contain mucosa? What are the three generic layers of all mucosa?

A

All GI tract contain mucosa. The three layers are –> 1.) Epithelium 2.) Lamina propria 3.) Muscularis mucosa

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12
Q

What type(s) of muscle is/are present in the esophagus and where? What is their embryonic origin?

A

Skeletal muscle (voluntary): Upper 1/3 (of pharyngeal arch origin)
Smooth AND skeletal (peristalsis takes over, involuntary): Middle 1/3 (foregut origin)
Smooth ONLY: Lower 1/3 (foregut origin)

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13
Q

Describe the structure and function of the esophagus

A

Muscular tube that carries food from the mouth to the stomach

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14
Q

What happens when the bolus damages cells of esophageal epithelium?

A

Basal stem cells replenish them (14.5 Wilson)

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15
Q

What characteristic of the esophageal muscularis is unique to the esophagus?

A

The presence of mixed skeletal (peripheral nuclei) and smooth muscle (centrally located nuclei).

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16
Q

What component of the esophageal mucosa help to lubricate and protect the mucosa? Where are they?

A

Small mucus-secreting submucosal ESOPHAGEAL GLANDS p.301

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17
Q

What type of epithelia are present at the transitional gastroesophageal junction?

A

Stratified squamous, nonkeratinized (espohageal) epithelium —to—> Simple columnar epithelium (of the stomach)

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18
Q

What happens to the gastroesophageal junction in GERD patients?

A

Esophageal mucosa changes to GASTRIC MUCOSA to protect the esophagus.

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19
Q

Where in the GI tract would there be high risk for cancer? Why?

A

At epithelial junctions (e.g. gastroesophageal junction) due to extremely active mitosis and differentiation.

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20
Q

What is name for the mix of food bolus and gastric secretions in the stomach?

A

Chyme

21
Q

What is the name of the region where the esophagus opens into the stomach?

A

The CARDIA

22
Q

What are the four distinct anatomical regions of the stomach? Which two are histologically identical?

A

p. 302 Junq
1. ) Fundus: Top portion.
2. ) Cardia: Near transition of esophagus to stomach.
3. ) Body
4. ) Pylorus: Near opening to duodenum.

Fundus and Body are histologically identical

23
Q

What are RUGAE?

A

p.303
Large, longitudinally directed folds in the mucosa and submucosa of the EMPTY stomach. They flatten when the stomach fills with food. They help to grind up the chyme.

24
Q

The deeper layers of the stomach are highly _______, why?

A

Vascularized –> This helps with two things:

  1. ) To clear out the bacteria from the gut quickly, e.g. in cases of food poisoning.
  2. ) It allows for rapid healing of the mucosa to avoid pain from bleeding ulcers, perotinitis, etc.
25
Q
  1. ) What type of organ is the stomach?

2. ) What are its functions?

A
  1. ) A mixed endocrine-exocrine organ (exdocrine = secretes digestive enzymes)
  2. ) Functions: Add acidic fluid to food, grinds food into chyme, secretion of pepsin.
26
Q
  1. ) What type of epithelium is present in the stomach?

2. ) How are the cardia, pylorus, and body histologically distinguished?

A
  1. ) Simple columnar epithelium.
  2. ) Glands of the cardia region are not very deep, in the body the glands become deeper, and are at their deepest in the PYLORI.
27
Q

Why are the epithelial cells clear in the gastric mucosa?

A

Due to the mucoid secretions of the cells

28
Q

What is the function of the gastric mucosa?

A

To secrete an alkaline/neutral fluid to protect the epithelium from the acid stomach secretions.

29
Q

What type of cells are found in the narrow segments between the gastric pits? Why?

A

Epithelial stem cells. Because it degrades rather quickly and is thus replaced with regularity.

30
Q

What are the five types of cells and their functions that lie from the gastric pit through the gastric gland? How does each cell stain?

A

p.305 Junq, 14.10-ish Wilson
1.) Surface mucous cells: Secretes ALKALINE fluid containing MUCIN.
Light staining with H&E.
2.) Mucous neck cells: Secrets ACIDIC fluid containing MUCIN. Light staining with H&E.
3.) Parietal cells: Secrets intrinsic factor and hydrochloric acid. Eosinophilic staining.
4.) Chief cells: Secretes pepsinogen and gastric lipase. Basophilic staining.
5.) G cell: enteroendocrine cells that secrete gastrin into the blood. No staining, need immunohistochemistry to visualize.

31
Q

Describe the histological appearance of the following cells:

  1. ) Mucous neck cells
  2. ) Parietal cells
  3. ) Chief cells
  4. ) G cells
A

p. 304-5
1. ) Less columnar than surface mucosal cells. Round nuclei and apical secretory granules.
2. ) Large cells (usually rounded or pyramidal) with 1-2 central round nuclei. Stains eosinophilic due to high density of mitochondria.
3. ) Lower region of gastric gland. Abundant RER w/ numerous apical secretory granules. Basal nuclei and BASOPHILIC cytoplasm.
4. ) Visualized with immunohistochemistry using antibodies against their product (???) –> Gastrin (peptide) or Serotonin.

32
Q

What are the three portions of the small intestine from proximal to distal

A

Duodenum, jejunum, ileum

33
Q

Where are vili present in the small intestine?

A

Present in ALL segments, but best developed in the JEJUNUM.

34
Q

What are the salient/distinguishing feature of each portion of the small intestine?

A
  1. ) Deuodenum: Submucosal glands.
  2. ) Jejunum: Villi
  3. ) Ileum: Peyer’s patches
35
Q

Describe the composition (cellular and tissue) of the intestinal villi

A

Covered by a simple columnar epithelium of absorptive cells called ENTEROCYTES, with many interspersed GOBLET CELLS. A lamina propria under loose connective tissue contains fibroblasts, smooth muscle fibers, fenestrated capillaries, and a central lymphatic vessel called a LACTEAL.

36
Q

What makes up the brush border of the small intestine?

A

Microvilli and glycocalyx.

37
Q

How does the concentration of goblet cells change as you move proximally to distally in the small intestine?

A

It increases from duodenum to ileum

38
Q

What are the mucous glands in the proximal duodenum called? Where else are they found? What do they drain into?

A

Brunner (duodenal) glands. Found EXCLUSIVELY in the duodenum. Drain into the crypts of Lieberkuhn.

39
Q

Where are the crypts of Lieberkuhn found?

A

14.50 Wilson

Throughout the small intestine. Only at the level of the DUODENUM are Brunner glands found draining into them.

40
Q

Describe the structure/functions of paneth cells

A

p.312 Junq, 14.40 Wilson
Located at the basal portion of the crypts of lieberkuhn BELOW the stem cells.

They are exocrine cells with large EOSINOPHILIC secretory granules in their apical cytoplasm. They release LYSOZYME, PHOSPHOLIPASE A, and hydrophobic peptides called DEFENSINS.

41
Q

Where are submucosal cells found in the GI tract?

A

Esophagus –> Mucous secreting for lubrication

Duodenum –> Brunner’s glands for lower pH of chyme

42
Q

What cells are very abundant in the colon? What is absent from the colon mucosa?

A

Goblet cells are prevalent. Villi are absent.

43
Q

What is the main function of the colon?

A

Water reabsorption. NO nutrient absorption.

44
Q

Describe the mucosa of the colon (4 things)

A
  1. ) Simple columnar epithelium with short microvilli (COLONOCYTES) and goblet cells (lining the TUBULAR GLANDS).
  2. ) No villi
  3. ) Straight mucus-secreting glands
  4. ) Abundant MALT in the lamina propria
45
Q

Describe the change in epithelium at the rectoanal junction. What is name of the dividing line?

A

Simple columnar epithelium w/ goblet cells at the COLON
Stratified squamous, nonkeratinized epithelium at the ANUS

Pectinate line = Endoderm + ectoderm

46
Q

What is the name of the line that divides the the inner portion of anus from the outer skin of the buttocks? What is the change in epithelium?

A

Hilton’s line (White line): Stratified squamous epithelium nonkeratinized (wet epithelium) –> stratified squamous keratinized epithelium (dry epithelium). Represents embryonic transition from proctodeum to ectoderm.

47
Q

What lines the lumen and gastric pits of the stomach? What exactly does it do?

A

(p.302)
Surface mucosal cells. They secrete a viscous mucous layer rich in BICARBONATE ions to protect the mucosa from both abrasion and corrosive effects of acid.

48
Q

In the _____ and _____, the gastric glands fill most of the mucosa.

A

In the FUNDUS and the BODY.

49
Q

How would you identify tissue in the large intestine?

A
  • Increased number of goblet cells compared to small intestine
  • No brush border (no microvilli)
  • Simple columnar epithelium with goblet cells <–4.18 Wilson

Histology (9 decks)

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