06 - Gastrointestinal system Flashcards
Describe the metaplasia in Barret esophagus. What is the cause? Higher risk for what disease?
- stratified squamous epithelium is transformed into a simple columnar epithelium.
- cause is extensive gastroesophageal reflux
- high risk for adenocarcinoma
What are the layers of the GIT? (from lumen outward) (Physiology p. 83)
- Mucosa - (epithelium, lamina propria, muscularis mucosa)
- Submucosa
- Muscularis
- Serosa
The neuroendrocrine cells located in the lamina propria of the gastrointestinal tract is known as
Argentaffin cells
Where is gastrin produced? What cells? (Physiology p. 84)
G cells of the antrum
Where are S cells found? What do they secrete? (Physiology p. 84)
S cells of the duodenum secrete secretin
Where are I cells found? What do the secrete? (Physiology p. 84)
I cells of the duodenum secrete cholecystokinin
Where are K cells found? What do the secrete? (Physiology p. 84)
K cells of the duodenum secrete GIP (glucose-dependent insulinotropic peptide)
Where are M cells found? What do the secrete? (Physiology p. 84)
M cells of the duodenum and jejunum secrete motilin
What type of cell is most prevalent within the gastric pit of the stomach?
Mucus-secreting cells
What do parietal cells secrete?
HCl and intrinsic factor
Destruction of parietal cells leads to a deficiency of this factor and causes what type of anemia? Explain pathophysiology
This leads to deficiency of intrinsic factor, which is important in the absorption of vitamin B12 cobalamin. Deficiency of cobalamin leads to pernicious anemia
What do chief cells secrete?
Pepsinogen
Identify: Permanent transverse folds that contain a core of submucosa and are circularly arranged (2 names);
What part of the GI tract is this a feature of?
Plicae circulares, a.k.a. Valves of Kerckring;
Feature of the small intestines
In the GI tract, another name for intestinal glands
Crypts of Lieberkuhn
Enumerate: cells of the crypts of Lieberkuhn and their functions/secretions.
- Enterocytes - columnar cells for absorption
- Goblet cells - mucin for mucus
- Paneth cells - lysozymes for innate immunity
- Enteroendocrine cells, a.k.a Argentaffin cells - hormones like secretin and motilin
What is the primary function of lacteals in the small intestine?
In which layer do they originate from?
- Absorption
- from the Lamina propria of the mucosa
Identify: these glands produce mucin-rich alkaline secretions for protection from acidic contents.
These glands are a feature of what part of the GI tract?
- Brunner gland
- duodenum
Plexus of nerves in the GI tract that control secretions.
In which layer is this plexus found?
Meissner plexus (submucosal plexus), found in the submucosa
Plexus of nerves in the GI tract that control motility.
In which layer is this plexus found?
Auerbach plexus (myenteric plexus), found in the muscularis layer between the inner circular layer and the outer longitudinal layer.
Histology of esophagus?
Non-keratinized stratified simple squamous