Flashcards in Lecture 13- Digestive Tract Deck (75)
What type of cells are the surface mucous cells?
Simple columnar epithelial cells
Why don't gastric contents normally injure the stomach mucosa?
Stomach mucosa is covered with mucus and bicarbonate that will neutralize acid
What happens at the apical cup of mucinogen granules?
Mucus and bicarbonate are secreted
What is the pH at the surface of mucosa and inside the stomach?
- Mucosa pH=7
- Stomach pH= 1
What affect can aspirin have on the stomach?
It can deteriorate the surface mucosa leading to stomach ulcers.
What are the for anatomical regions of the stomach?
What are the three histological regions of the stomach?
* differences in mucosa
Describe the cardiac region of the stomach
- simple columnar epithelium
- cardiac glands present that secrete mucus
What types of glands are present in the fundus/body?
What are the three parts of gastric glands and how does their size compare to cardiac glands?
-much larger than cardiac glands
What do surface mucus cells in gastric pit secrete?
Alkaline mucous and bicarbonate
What do mucous neck cells secrete?
more neutral mucous
What do parietal cells in the isthmus/neck secrete?
HCl and intrinsic factor
What do chief cells in the base secrete?
Pepsinogen and gastric lipase
How do parietal cells secrete acid?
They use a Hydrogen-Potassium ATPase pump
What organelles have proton pumps in parietal cells?
- Canaliculi with microvilli
What is the role of mitochondria in the parietal cells?
- Lots of ATP is needed to run the proton pump
What happens when food is digested?
Tubulovesicles with the proton pump fuse with the canaliculi membrane
Why is there acid in the stomach? (3)
- helps kill bacteria
- acid and intrinsic factor important for Vitamin B12 absorption
- acid converts pepsinogen to pepsin
Where are the pyloric glands found?
What types of cells are found in the plylorous?
- surface mucous cells
- mucous neck cells
- G cells
- Enteroendocrine cells
What are the distinct features of pyloric glands?
- deeper pits
- shorter coiled pyloric glands
What stimulates the release of gastrin?
What do enterochromaffin-like cells do?
Release histamine that releases acid
What cells bind to enterochromaffin-like cells?
Gastrin and ACh from parasympathetic response
Blocking the secretions of what kinds of cells would potentially treat gastroesophageal reflux disease?
- G cells (gastrin)
- Parietal cells (acid)
- enterochromaffin-like cells (histamine)
What makes up the pyloric sphincter?
- Smooth muscles thickening the middle layers of the stomach muscularis
Do the circular folds of the small intestine change shape during digestion?
What is the main role of the small intestine?
Absorb nutrients and minerals from food