Stomach Histology Flashcards
What are the four layers of the gastric wall?
Mucosa
Submucosa
Muscularis
Serosa
The mucosa is made from _______ ______ _______ that live _____ days and are then replaced
simple columnar epithelium
3-6 days
What prevents acid penetration between the epithelial cells in the mucosa?
Tight junctions
What are gastric pits?
Holes in the gastric mucosa, are the entrance to the gastric glands
Each gastric pit open into ____ (number) of _____ glands
2-3
gastric glands
What epithelium lines a gastric gland?
Simple columnar
Gastric glands extend through the ______ _______ (a layer of the submucosa).
Lamina propria
What 4 types of cells are present in a gastric gland?
Chief cells
Parietal cells
Mucus cells
G-Cells
Why are chief cells named as such? Where are they found?
Named because they are the most numerous cells in the gastric gland
Found mostly in lower half of the gastric glands
As an infant, what does a chief cell secrete?q
Gastric lipase
What do chief cells secrete?
Pepsinogen
What does pepsinogen change to? What does it do?
Changes into pepsin, which digests proteins
Where does protein digestion begin? Carbohydrate digestion?
Protein- Stomach
Carbohydrate- Mouth
What does it mean that pepsinogen is autocatalytic?
Pepsin turns to pepsinogen with ambient HCl
Where are parietal cells found?
Mostly in the upper half of gastric glands
What 2 things are secreted by parietal cells?
HCl
Intrinsic factor
What does HCl do in the body?
Changes Fe3+ to Fe2+ (so we can absorb it)
Denatures proteins, (changes shape of protein, helps to digest)
Changes pepsinogen into pepsin
Kills microbes
What is intrinsic factor?
A glycoprotein
What does intrinsic factor do?
Must have present for absorption of vitamin B12
Why is vitamin B12 important?
Vitamin B12 is used to make hemoglobin
What conditions occurs without intrinsic factor?
Pernicious anemia (inability to create Hb)
Where does the body get HCl?
H+ from bicarb storage joins Cl from the chloride shift
What is the specific name of the mucus cells? Why are named as such?
Mucus neck cells
Because mainly in the neck of mucus gland
What do mucus neck cells do?
Protect the stomach walls
What is a G-Cell also called? Where is it found?
Gastrin
Always found at the end of the gastric gland
What forms gastrin?
Formed by enteroendocrine cells
What do G-cells do?
1- ↑ HCl from parietal cells
2- ↑ pepsinogen from chief cells
3- Contracts lower esophageal sphincter (LES) to protect esophagus from ↑ acid
4- ↑ motility of stomach- to start digestion
5- Relaxes pyloric sphincter
What is in the submucosa? What isn’t in it?
Just CT and blood vessels
No glands- they’re in the mucosa here
What is the purpose of the muscularis layer?
Mechanical digestion
What are the three layers of the muscularis?
Inner oblique- Mostly in the body of the stomach
Middle circular
Outer longitudinal
How does the muscularis move?
Peristaltic movements here every 15-20 seconds, no segmentation; just mixing of chyme
The muscularis pushes chyme towards the _______.
Pylorus
What are the two serous membranes of the stomach? What do they connect?
Lesser omentum- Connects lesser curvature of stomach to the liver
Greater omentum- Greater curvature, down and back on itself, to the transverse colon
How much gastric juice do we make?
What it is made from?
Make 2-3 L/day
Mainly water, HCl, and pepsin
What 3 things protect us from gastric juice?
1- Mucus in stomach
2- Tight junctions
3- Epithelial cell replacement
