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GI Midterm > Lecture 7-Histology Of Esophagus And Stomach > Flashcards

Lecture 7-Histology Of Esophagus And Stomach Flashcards

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1
Q

Four layers of the GI tract

-Mucosa-3 components?

A

Epithelium, lamina propria, muscularis mucosa

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2
Q

Four layers of the GI tract

-Submucosa?

A

Connective tissue that contains glands, blood vessels, nerves

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3
Q

Four layers of the GI tract

-Muscularis externa?

A

Two to three layers of smooth muscles

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4
Q

Four layers of the GI tract

  • Adventitia and serosa
    • Where are each of these seen?
    • What are they?
A

Adventitia-esophagus, most of duodenum
Serosa-rest of GI tract
CT that supports and binds other organs

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5
Q

The mucosa has three components?

A
  • A lining epithelium with mucosal and submucosal glands and ducts
  • An underlying lamina propria consisting of a vascularized loose CT
  • A thin layer of smooth muscle, the muscularis mucosae
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6
Q

Mucosa

  • Epithelium histology?
    • Function?
A
  • Stratified squamous and simple columnar
  • Function
    • selectively permeable barrier
    • transport, digestion, absorption
    • produces hormones
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7
Q

Mucosa

  • Lamina propria
    • what is found here?
    • What is special about the lamina propria found in the small and large intestines?
A
  • Vascularized loose CT
  • Lymphatic nodules and scattered immunocompetent cells
  • Lamina propria of the small and large intestines is a relevant site of immune responses (peyer’s patch or GALT)
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8
Q

Mucosa

  • Muscularis mucosae
    • What is it?
    • Functions?
A
  • A thin double layer of smooth muscle is often present
  • Increases contact area with food
  • Propel and mix food in GI tract
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9
Q

Submucosa

  • Consists of?
  • Glands are present in the submucosa of what GI organs?
A
  • Consists of a dense irregular CT with large blood vessels, lymphatics, and nerves branching into the mucosa and muscularis
  • Glands are present in the submucosa of the esophagus and duodenum
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10
Q

Mucosa and submucosa in the stomach compared to mucosa and submucosa in the small intestine?

A

Mucosa and submucosa extend into the lumen as folds

  • stomach-rugae
  • small intestine-plicae
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11
Q

Mucosal gland-function?

A

Increase secretory capacity

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12
Q

Mucosa alone can extend into the lumen-called?

A

Fingers/villi

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13
Q

Muscularis externa

-2 layers of? What are they called?

A

-Contains two layers of smooth muscle-circular layer and longitudinal layer

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14
Q

Muscularis externa

  • Circular layer
    • Description?
    • Function?
A
  • Circular layer-inner layer is arranged around the tube lumen
  • Contraction of the smooth fibers of the circular layer reduces the lumen
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15
Q

Muscularis externa

  • Longitudinal layer
    • Description?
    • Function?
A
  • Longitudinal layer- fibers of the outer layer are disposed along the tube
    • contraction of the fibers of the longitudinal layer shortens the tube
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16
Q

Adventitia

A
  • Outside the peritoneal cavity
  • Binds to the body wall
  • Loose CT
  • Blood vessels and nerves
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17
Q

Serosa

A
  • Within the peritoneal cavity
  • Loose CT
  • Simple squamous epithelium
  • Blood vessels, nerves adipose tissue
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18
Q

Innervation of the GI tract allows it to respond to?

A

Both local stimuli and ANS input

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19
Q

GI tract innervation

-Extrinsic (ANS)-Effect of sympathetic (TL)?

A

Decreases motility and secretions

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20
Q

GI tract innervation

-Extrinsic (ANS)-Effect of parasympathetic (Vagus)?

A

Increases motility/secretions

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21
Q

GI tract innervation

  • Intrinsic/enteric
    • Myenteric plexus is between what 2 layers?
A

Between the inner/circular and outer/longitudinal layers of muscularis externa

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22
Q

GI tract innervation

  • Intrinsic/enteric
    • description?
    • Contains what 2 plexi?
A
  • Distinct, interconnected neuronal circuits
  • Meissner’s plexus
  • Myenteric plexus
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23
Q

GI tract innervation

  • Intrinsic/enteric
    • Functions?
A
  • Peristaltic contractions to move bolus

- Secretory activity of mucosal and submucosal glands

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24
Q

Esophagus-Location?

A

Lies posterior to the trachea in the thoracic cavity, except for its distal end, which passes through the diaphragm into the abdominal cavity

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25
Lower esophageal sphincter
Just anterior to the gastroesophageal junction, helps prevent reflux and regurgitation of stomach contents through contraction and must relax to allow food passage with swallowing -There is also a upper esophageal sphincter near the cricopharyngeus muscle
26
Esophagus | -What happens at the gastroesophageal junction?
- At the gastroesophageal junction, the mucosa transitions from the stratified squamous epithelium of the esophagus to simple columnar epithelium and glandular secretory mucosa - The muscularis mucosa, submucosa, and muscularis propria are continuous through this junction
27
Portal-caval anastomoses | -Increase in portal venous pressure?
-Increase in portal venous pressure results in dilation of veins (esophageal varices)
28
Mucosal and submucosal glands | -Continuously produce?
Continuously produce a thin layer of mucous to lubricate the epithelial surface
29
Muscularis externa in the esophagus
- Inner circular and outer longitudinal - Segment dependent variation - Upper 1/3-skeletal muscle - Middle 1/3-transition, primarily smooth muscle - Lower 1/3-smooth muscle
30
Esophagus has 2 sphincters | -Upper sphincter?
Anatomically defined, cricothyroid | Participates in initiation of swallowing
31
Esophagus has 2 sphincters | -Lower esophageal?
Functionally defined, gastroesophageal sphincter | Prevents gastric reflux
32
Barrett's Esophagus
- Condition in which an abnormal columnar epithelium replaces the stratified squamous epithelium that normally lines the esophagus - Most severe histologic consequence of chronic GERD
33
GERD
Change in epithelium to columnar (like stomach), chronic esophagitis/ulceration, dysphagia, fibrosis a/o esophageal strictures
33
``` Digestive tube (made up of 4 organs-esophagus, stomach, small intestine, and large intestine) -Each of these organs is made up of four concentric layers (inside to outside)? ```
Mucosa, submucosa, muscularis externa, and adventitia/serosa Adventitia for esophagus and most of duodenum Serosa for rest of GI tract
35
Stomach | -Protective layer of mucous protects surface epithelium from?
- Mechanical ingestion by ingested foods | - Destructive effects of acids and hydrolytic enzymes
36
Gastric glands | -Contain 5 major cell types?
- Mucous neck cells - Chief cells - Parietal cells - Stem cells - Gastroenteroendocrine cells
37
- The gastric mucosa contains of the fundus-body has 2 classes of mucus-producing cells? - Where are they each located?
- Surface mucous cells lining the pit | - Mucous neck cells located at the opening of the gastric gland into the pit
38
Both types of mucous cells produce?
Mucins with glycoproteins to form a protective mucus layer
39
Surface and neck mucous cells produce: | -Protective mucus layer-function?
-Traps bicarbonate ions and neutralizes the microenvironment adjacent to the apical region of the surface mucous cells to an alkaline pH
40
Chief cells | -Where are they located in the gastric gland?
- Predominate in the lower third of the gastric gland | - Chief cells are not present in cardiac glands and are seldom found in the pyloric antrum
41
Chief cells-What do they secrete?
Pepsinogen which is then converted to pepsin by the acidic environment
42
Parietal cells secrete?
HCl and intrinsic factor
43
Autoimmune gastritis - Caused by? - What results from this?
- Autoantibodies to H+K+-dependent ATPase, a parietal cell Ag, and autoantibodies to intrinsic factor - Destruction of parietal cells causes a reduction in HCl in the gastric juice (achlohydria) and a lack of synthesis of intrinsic factor - Vitamin B12 deficiency-->disrupts formation of RBCs-->pernicious anemia
44
Secretion of HCl by parietal cells is stimulated by what substances? -These substances are produced by?
The parasympathetic mediator ACh and the peptide gastrin produced by enteroendocrine cells of the pyloric antrum -ACh also stimulates gastrin release
45
Gastric juice | -A combination of two separate secretions?
- An alkaline mucosal gel protective component-always present - HCl and pepsin-levels vary because the levels increase after food intake
46
H. pylori | -Where is the stomach particularly vulnerable to this organism?
- In the gastric epithelium particularly in the pyloric antrum - Survives and replicates in the gastric lumen
47
H. pylori | -Presence of this bacteria is associated with?
Acid peptic ulcers and adenocarcinoma of the stomach
48
The function of the alimentary tube is regulated by what 2 substances? -What are each of these produced by?
- Peptide hormones produced by gastroenteroendocrine cells | - Neuroendocrine mediators produced by neurons
49
Peptide hormones produced by gastrointestinal endocrine cells have the following general functions?
- Regulation of water, electrolyte metabolism, and enzyme secretion - Regulation of GI motility and mucosal growth - Stimulation of the release of other peptide hormones
50
Peptide hormones | -Secretin-released by? When?
Cells in the duodenal glands of Lieberkuhn when the gastric contents enter the duodenum
51
Secretin-function? - With CCK? - With ACh?
- Stimulates pancreatic and duodenal (Brunner's glands) bicarbonate and fluid release - Together with CCK secretin stimulates the growth of the exocrine pancreas - Secretin and ACh stimulates chief cells to secrete pepsinogen, and inhibits gastrin release to reduce HCl secretion in the stomach
52
Gastrin | -produced by? Where are these cells located?
G cells located in the pyloric antrum
53
Gastrin-main function?
- Stimulates the production of HCl by parietal cells | - Can also activate CCK to stimulate gall bladder contraction
54
CCK-where is it produced?
In the duodenum
55
CCK-function?
Stimulates gall bladder contraction and relaxation of the sphincter of Oddi when protein and fat rich chyme enters the duodenum
56
GIP-where is it produced?
In the duodenum
57
GIP-function?
Stimulates insulin release when glucose is detected in the small intestine
58
Motilin - release is regulated by? - released by?
A neural control mechanism-released cyclically (every 90 mins) during fasting from the upper small intestine
59
Motilin-function?
Stimulates GI motility
60
Ghrelin-where is it produced?
Stomach (fundus)
61
Where does Ghrelin bind?
-To its receptor in growth hormone secreting cells in the anterior hypophysis
62
Ghrelin-function?
Stimulates the secretion of growth hormone
63
When do ghrelin levels increase? | -What does this trigger?
Ghrelin plasma levels increase during fasting triggering hunger by acting on hypothalamic feeding centers
64
Mucosa, submucosa, and muscularis externa - Lamina propria - types of fibers? - types of cells?
- Reticular and collagen fibers predominate in the lamina propria - Cells-fibroblasts, lymphocytes, mast cells, eosinophils, and plasma cells
65
Submucosa consists of?
- Dense irregular CT-abundant collagenous and elastic fibers - Large number of arterioles, venous plexuses, and lymphatics - Meissner's plexus
66
Muscularis externa - Consists of three poorly defined layers of what type of muscle? - what are the layers?
Smooth muscle-circular, oblique, and longitudinal
67
Muscularis externa-which layer of muscle forms the annular pyloric sphincter?
The circular muscle
68
Meissner's plexus is located in what layer?
Submucosal layer

GI Midterm (11 decks)

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