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

Lecture 7-Histology Of Esophagus And Stomach Flashcards

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
Q

Lower esophageal sphincter

A

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

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26
Q

Esophagus

-What happens at the gastroesophageal junction?

A
  • 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
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27
Q

Portal-caval anastomoses

-Increase in portal venous pressure?

A

-Increase in portal venous pressure results in dilation of veins (esophageal varices)

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28
Q

Mucosal and submucosal glands

-Continuously produce?

A

Continuously produce a thin layer of mucous to lubricate the epithelial surface

29
Q

Muscularis externa in the esophagus

A
  • 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
Q

Esophagus has 2 sphincters

-Upper sphincter?

A

Anatomically defined, cricothyroid

Participates in initiation of swallowing

31
Q

Esophagus has 2 sphincters

-Lower esophageal?

A

Functionally defined, gastroesophageal sphincter

Prevents gastric reflux

32
Q

Barrett’s Esophagus

A
  • 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
Q

GERD

A

Change in epithelium to columnar (like stomach), chronic esophagitis/ulceration, dysphagia, fibrosis a/o esophageal strictures

33
Q 
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)?
A

Mucosa, submucosa, muscularis externa, and adventitia/serosa

Adventitia for esophagus and most of duodenum
Serosa for rest of GI tract

35
Q

Stomach

-Protective layer of mucous protects surface epithelium from?

A
  • Mechanical ingestion by ingested foods

- Destructive effects of acids and hydrolytic enzymes

36
Q

Gastric glands

-Contain 5 major cell types?

A
  • Mucous neck cells
  • Chief cells
  • Parietal cells
  • Stem cells
  • Gastroenteroendocrine cells
37
Q
  • The gastric mucosa contains of the fundus-body has 2 classes of mucus-producing cells?
    • Where are they each located?
A
  • Surface mucous cells lining the pit

- Mucous neck cells located at the opening of the gastric gland into the pit

38
Q

Both types of mucous cells produce?

A

Mucins with glycoproteins to form a protective mucus layer

39
Q

Surface and neck mucous cells produce:

-Protective mucus layer-function?

A

-Traps bicarbonate ions and neutralizes the microenvironment adjacent to the apical region of the surface mucous cells to an alkaline pH

40
Q

Chief cells

-Where are they located in the gastric gland?

A
  • 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
Q

Chief cells-What do they secrete?

A

Pepsinogen which is then converted to pepsin by the acidic environment

42
Q

Parietal cells secrete?

A

HCl and intrinsic factor

43
Q

Autoimmune gastritis

  • Caused by?
  • What results from this?
A
  • 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
Q

Secretion of HCl by parietal cells is stimulated by what substances?
-These substances are produced by?

A

The parasympathetic mediator ACh and the peptide gastrin produced by enteroendocrine cells of the pyloric antrum
-ACh also stimulates gastrin release

45
Q

Gastric juice

-A combination of two separate secretions?

A
  • An alkaline mucosal gel protective component-always present
  • HCl and pepsin-levels vary because the levels increase after food intake
46
Q

H. pylori

-Where is the stomach particularly vulnerable to this organism?

A
  • In the gastric epithelium particularly in the pyloric antrum
  • Survives and replicates in the gastric lumen
47
Q

H. pylori

-Presence of this bacteria is associated with?

A

Acid peptic ulcers and adenocarcinoma of the stomach

48
Q

The function of the alimentary tube is regulated by what 2 substances?
-What are each of these produced by?

A
  • Peptide hormones produced by gastroenteroendocrine cells

- Neuroendocrine mediators produced by neurons

49
Q

Peptide hormones produced by gastrointestinal endocrine cells have the following general functions?

A
  • Regulation of water, electrolyte metabolism, and enzyme secretion
  • Regulation of GI motility and mucosal growth
  • Stimulation of the release of other peptide hormones
50
Q

Peptide hormones

-Secretin-released by? When?

A

Cells in the duodenal glands of Lieberkuhn when the gastric contents enter the duodenum

51
Q

Secretin-function?

  • With CCK?
  • With ACh?
A
  • 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
Q

Gastrin

-produced by? Where are these cells located?

A

G cells located in the pyloric antrum

53
Q

Gastrin-main function?

A
  • Stimulates the production of HCl by parietal cells

- Can also activate CCK to stimulate gall bladder contraction

54
Q

CCK-where is it produced?

A

In the duodenum

55
Q

CCK-function?

A

Stimulates gall bladder contraction and relaxation of the sphincter of Oddi when protein and fat rich chyme enters the duodenum

56
Q

GIP-where is it produced?

A

In the duodenum

57
Q

GIP-function?

A

Stimulates insulin release when glucose is detected in the small intestine

58
Q

Motilin

  • release is regulated by?
  • released by?
A

A neural control mechanism-released cyclically (every 90 mins) during fasting from the upper small intestine

59
Q

Motilin-function?

A

Stimulates GI motility

60
Q

Ghrelin-where is it produced?

A

Stomach (fundus)

61
Q

Where does Ghrelin bind?

A

-To its receptor in growth hormone secreting cells in the anterior hypophysis

62
Q

Ghrelin-function?

A

Stimulates the secretion of growth hormone

63
Q

When do ghrelin levels increase?

-What does this trigger?

A

Ghrelin plasma levels increase during fasting triggering hunger by acting on hypothalamic feeding centers

64
Q

Mucosa, submucosa, and muscularis externa

  • Lamina propria
    • types of fibers?
    • types of cells?
A
  • Reticular and collagen fibers predominate in the lamina propria
  • Cells-fibroblasts, lymphocytes, mast cells, eosinophils, and plasma cells
65
Q

Submucosa consists of?

A
  • Dense irregular CT-abundant collagenous and elastic fibers
  • Large number of arterioles, venous plexuses, and lymphatics
  • Meissner’s plexus
66
Q

Muscularis externa

  • Consists of three poorly defined layers of what type of muscle?
  • what are the layers?
A

Smooth muscle-circular, oblique, and longitudinal

67
Q

Muscularis externa-which layer of muscle forms the annular pyloric sphincter?

A

The circular muscle

68
Q

Meissner’s plexus is located in what layer?

A

Submucosal layer

GI Midterm (11 decks)

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