Flashcards in Stomach Histology Week 1 Deck (47):
Georg Meissner described and named the Meissner's plexus and Meissner's corpuscles. Describe these two structures.
Meissner's plexus = submucosal plexus of alimentary tract
Meissner's corpuscles = mechanoreceptor
Leopold Auerbach described and named the Auerbach's plexus. Describe this structure
The Auerbach's plexus is the mesenteric plexus of the alimentary tract
The _____ of the stomach is a surface covered by gastric pits that open into ______
rugae, gastric glands
what three regions is the stomach histologically divided into?
cardiac region - cardiac glands
fundus and body - gastric glands
pyloric - pyloric glands
The fundus and body contain gastric glands. What are the two components of these glands?
gastric gland proper
________ line the stomach and continue into the gastric pits
surface mucous cells
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 ________
insoluble, thick; bicarbonate; gastric mucus blanket
The ______ protects the surface epithelium from mechanical erosion and from destructive effect of acid and hydrolytic enzymes present in the gastric juice
protective layer of mucus
In the gastric gland proper, there are _____ which form _____. The H+ ions come from dissociation of _________
parietal cells, Hcl, carbonic acid
What are rugae? What is their function?
longitudinal folds of gastric mucosa and soft mucosa
rugae allow the stomach to distend when filled
Describe the structure of the gastric mucosa
Consists of gastric glands, surrounded by the lamina propria containing capillaries, and the muscularis mucosae
What is the alkaline tide?
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
How many layers does the muscularis externa of the stomach have? What are they layers?
inner oblique, middle circular, outer longitudinal
True/False: The inner oblique layer of the muscularis externa of the stomach is complete
The thick middle circular layer of the stomach's muscularis externa contains what two structures?
It forms the pyloric sphincter
and contains the myenteric plexus
What are the four layers of the stomach
mucosa, submucosa, muscularis externa, serosa
What are the three layers of the stomach mucosa?
epithelium, lamina propria, muscularis mucosae
Which layer of the stomach mucosa contains the surface mucous lining cells?
these cells lead into a gastric pit opening into a gastric gland
What are the four components of the stomach's lamina propria?
smooth muscle, connective tissue, gastric glands, lymphatic nodules
What are the three layers of the stomach's muscularis mucosae located within the mucosa?
inner incomplete oblique muscle, middle circular muscle, outer longitudinal
SAME AS MUSCULARIS EXTERNA - but muscularis externa has thicker middle circular layer.
What are the two main functions of the stomach?
1) acidifies and converts bolus into chyme
2) produces digestive enzymes pepsin, renin and gastric lipase and some hormones
What is the function of the oblique layers of the stomach?
adds churning ability to the stomach
stomach churns and mixes all the chyme with the acidic environment and enzymes pumped into the cell
True/False: The pyloric sphincter is made up of longitudinal muscle
FALSE - made up of middle circular muscle
True/False: The myenteric plexus is found within the inner oblique layer
FALSE - within middle circular layer
True/False: Organs within the peritoneal cavity have a serosa
Name the 5 cell types associated with the gastric gland
1) mucus neck cells
2) stem cells
3) parietal cells
4) chief cells
5) enteroendocrine cells
What is unique about stem cells located in the gastric gland compared to in other areas?
stem cells are usually unidirectional
in the gastric gland, they are bidirectional
What are the two functions of parietal cells?
1) secrete Hcl
2) secrete gastric intrinsic factor
Describe how parietal cells secrete Hcl
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
True/False: Parietal cells contain abundant mitochondria which use ATP to pump H+
The low pH of the gastric juices (about 2) helps convert _______ to ________
The parietal cells of the stomach also secrete gastric intrinsic factor. Describe the function of GIF
GIF binds to vitamin b12 and facilitates its absorption in the ileum
What is pernicious anemia?
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
What is the function of chief cells?
secrete pepsinogen and precursors to renin (chymosin) and lipase
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) 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
True/False: Chief cells stain better with basophilic substances whereas parietal cells stain better with eosin stains
What is distinctive of parietal cell structure? Chief cells?
Parietal cells have large amount of mitochondria
Chief cells have large amount of rough ER in basal portion
Why does the staining in the chief cell apical region vary?
Zymogen granules containing pepsinogen and a weak lipase are not always preserved
Describe the function of enteroendocrine cells.
What are they also called?
produce endocrine and paracrine secretions
AKA APUD or ELC (enterochromaffin like) cells
True/False: enteroendocrine cells stain easily with eosin
false - need special stain
Where do enteroendocrine cells tend to be located?
towards the bottom portion of the gastric gland
What stimulates production of acid from enteroendocrine cells?
Before the days of proton pump inhibitors being readily available, how did tylenol treat acid reflux?
blocks histamine --> blocks acid production
True/False: The enteroendrine cells reach the epithelial surface
What is distinctive of the appearance of enteroendocrine cells in H&E stained sections?
the nucleus appears to be surrounded by a small amount of clear cytoplasm
Besides histamine, what are 6 other substances secreted by gastric enterochromaffin-like cells (ELC)?
vasoactive intestinal peptide
alpha and gamma endorphin