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B3 > Stomach Histology Week 1 > Flashcards

Stomach Histology Week 1 Flashcards

1
Q

Georg Meissner described and named the Meissner’s plexus and Meissner’s corpuscles. Describe these two structures.

A

Meissner’s plexus = submucosal plexus of alimentary tract

Meissner’s corpuscles = mechanoreceptor

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2
Q

Leopold Auerbach described and named the Auerbach’s plexus. Describe this structure

A

The Auerbach’s plexus is the mesenteric plexus of the alimentary tract

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3
Q

The _____ of the stomach is a surface covered by gastric pits that open into ______

A

rugae, gastric glands

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4
Q

what three regions is the stomach histologically divided into?

A

cardiac region - cardiac glands
fundus and body - gastric glands
pyloric - pyloric glands

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5
Q

The fundus and body contain gastric glands. What are the two components of these glands?

A

gastric pit

gastric gland proper

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6
Q

________ line the stomach and continue into the gastric pits

A

surface mucous cells

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7
Q

In the gastric pit, surface mucous cells produce an ________, ______ mucous. They also produce ______ which gets trapped in this mucous coat.
This substance is referred to as the ________

A

insoluble, thick; bicarbonate; gastric mucus blanket

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8
Q

The ______ protects the surface epithelium from mechanical erosion and from destructive effect of acid and hydrolytic enzymes present in the gastric juice

A

protective layer of mucus

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9
Q

In the gastric gland proper, there are _____ which form _____. The H+ ions come from dissociation of _________

A

parietal cells, Hcl, carbonic acid

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10
Q

What are rugae? What is their function?

A

longitudinal folds of gastric mucosa and soft mucosa

rugae allow the stomach to distend when filled

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11
Q

Describe the structure of the gastric mucosa

A

Consists of gastric glands, surrounded by the lamina propria containing capillaries, and the muscularis mucosae

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12
Q

What is the alkaline tide?

A

The alkaline tide refers to a condition, normally after eating a meal, where during the production of Hcl by parietal cells in the stomach, the parietal cells secrete bicarb ions across their basolateral membranes and into the blood, causing a temporary inc in pH

These bicarbonate ions enter a fenestrated capillary in the lamina propria, with blood flowing towards the surface epithelium

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13
Q

How many layers does the muscularis externa of the stomach have? What are they layers?

A

3
IOMCOL
inner oblique, middle circular, outer longitudinal

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14
Q

True/False: The inner oblique layer of the muscularis externa of the stomach is complete

A

FALSE INCOMPLETE

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15
Q

The thick middle circular layer of the stomach’s muscularis externa contains what two structures?

A

It forms the pyloric sphincter

and contains the myenteric plexus

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16
Q

What are the four layers of the stomach

A

mucosa, submucosa, muscularis externa, serosa

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17
Q

What are the three layers of the stomach mucosa?

A

epithelium, lamina propria, muscularis mucosae

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18
Q

Which layer of the stomach mucosa contains the surface mucous lining cells?

A

the epithelium

these cells lead into a gastric pit opening into a gastric gland

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19
Q

What are the four components of the stomach’s lamina propria?

A

smooth muscle, connective tissue, gastric glands, lymphatic nodules

20
Q

What are the three layers of the stomach’s muscularis mucosae located within the mucosa?

A

inner incomplete oblique muscle, middle circular muscle, outer longitudinal

SAME AS MUSCULARIS EXTERNA - but muscularis externa has thicker middle circular layer.

21
Q

What are the two main functions of the stomach?

A

1) acidifies and converts bolus into chyme

2) produces digestive enzymes pepsin, renin and gastric lipase and some hormones

22
Q

What is the function of the oblique layers of the stomach?

A

adds churning ability to the stomach

stomach churns and mixes all the chyme with the acidic environment and enzymes pumped into the cell

23
Q

True/False: The pyloric sphincter is made up of longitudinal muscle

A

FALSE - made up of middle circular muscle

24
Q

True/False: The myenteric plexus is found within the inner oblique layer

A

FALSE - within middle circular layer

25
Q

True/False: Organs within the peritoneal cavity have a serosa

A

true

26
Q

Name the 5 cell types associated with the gastric gland

A

1) mucus neck cells
2) stem cells
3) parietal cells
4) chief cells
5) enteroendocrine cells

27
Q

What is unique about stem cells located in the gastric gland compared to in other areas?

A

stem cells are usually unidirectional

in the gastric gland, they are bidirectional

28
Q

What are the two functions of parietal cells?

A

1) secrete Hcl

2) secrete gastric intrinsic factor

29
Q

Describe how parietal cells secrete Hcl

A

Parietal cells contain intracellular cannaliculi which deliver acid to the lumen.
The tubovesicular system is associated with these cannaliculi.
When more acid needed in the stomach, the parietal cells will recruit portions of the tubovesicular system and turn them into auxillary intracellular cannaniculi for more acid production

30
Q

True/False: Parietal cells contain abundant mitochondria which use ATP to pump H+

A

TRUE

31
Q

The low pH of the gastric juices (about 2) helps convert _______ to ________

A

pepsinogen, pepsin

32
Q

The parietal cells of the stomach also secrete gastric intrinsic factor. Describe the function of GIF

A

GIF binds to vitamin b12 and facilitates its absorption in the ileum

33
Q

What is pernicious anemia?

A

It is an autoimmune disease in which autoantibodies are produced against GIF or parietal cells
The lack of GIF decreases B12 levels which are essential for RBC maturation

34
Q

What is the function of chief cells?

A

secrete pepsinogen and precursors to renin (chymosin) and lipase

35
Q

How often are the following cells replaced?

a) surface mucous and mucous neck cells
b) gastric gland cells
- parietal cells
- chief and enterendocrine cells

A

a) surface mucous and mucous neck cells= replaced every 3-6 days
b) parietal cells = 150-200 days; chief and enteroendrocrine cells =60-90 days

overall, gastric gland cells are replaced at relatively slower rate compared to surface mucous and mucous neck cells

36
Q

True/False: Chief cells stain better with basophilic substances whereas parietal cells stain better with eosin stains

A

true

37
Q

What is distinctive of parietal cell structure? Chief cells?

A

Parietal cells have large amount of mitochondria

Chief cells have large amount of rough ER in basal portion

38
Q

Why does the staining in the chief cell apical region vary?

A

Zymogen granules containing pepsinogen and a weak lipase are not always preserved

39
Q

Describe the function of enteroendocrine cells.

What are they also called?

A

produce endocrine and paracrine secretions

AKA APUD or ELC (enterochromaffin like) cells

40
Q

True/False: enteroendocrine cells stain easily with eosin

A

false - need special stain

41
Q

Where do enteroendocrine cells tend to be located?

A

towards the bottom portion of the gastric gland

42
Q

What stimulates production of acid from enteroendocrine cells?

A

histamine

43
Q

Before the days of proton pump inhibitors being readily available, how did tylenol treat acid reflux?

A

blocks histamine –> blocks acid production

44
Q

True/False: The enteroendrine cells reach the epithelial surface

A

FALSE

45
Q

What is distinctive of the appearance of enteroendocrine cells in H&E stained sections?

A

the nucleus appears to be surrounded by a small amount of clear cytoplasm

46
Q

Besides histamine, what are 6 other substances secreted by gastric enterochromaffin-like cells (ELC)?

A 
cholecystokinin
somatostatin
vasoactive intestinal peptide
substance P
alpha and gamma endorphin
47
Q

What do the ELC’s D cells secrete? G cells?

What are the actions of these substances?

A

somatostatin secreted by D cells; inhibits acid

gastrin secreted by G cells; stimulates acid

B3 (7 decks)

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