Dig sys Flashcards
Going from the duodenum → ileum, what happens to:
lymphocyte + villi
More lymphocytes (peyers patches) Villi get shorter See more goblet sells (more mucus secreted)
1 Duct cells secrete
2 Acinar cells secrete
3 Islets of langerhans secrete
(endocrine portion)
1 NaHCO3
2 Digestive enzymes
3 Insulin, glucagon
- well vascularized (makes sense, H goes to blood)
(all in pancreas)
Chief cells secrete
parietal cells (fried egg) secrete
pepsinogen
HCl + IF
- targets for PPI
What type of cells do you expect to see in duodenum? What do they secrete
Brunners gland: secrete HCO3 to neutralize chyme.
longer villi than ileum
- only in duod
- also secrete mucin
Panneth cells (at bottom of crypts): secretes defensins, lysozymes, phospholipases
Enterocyte fxn
- Enterokinase found at surface: activates trypsinogen
- Lactase, maltase, sucrase: degrade dissacharides → monosaccharides
- Uptake Monoglycerides and FA
- resynthesizes them to triglycerides and release by exocytosis - Reuptake bile salts in micelles
- take up peptides + degrade them on route
- Move IgA (opp direction towards villi than the rest)
What type of nervous system regulate a produce local gut motility? What fxn does the coordinated input from the CNS provide?
Intrinsic (enteric) NS outside of the CNS
Coordinated input from parasympathetic fibers and sympathetic fibers from the CNS allows
- coordination of peristalsis
- affect blood vessels and glands
structural properties of smooth muscle in the gut that contribute to its performance as a single functional unit
SM cells are held together by mechanical jxns that are connected to eachother via gap jxns (allowing cell-cell communication)
- innervated by autonomic nerves, capable of activating mult muscle cells
4 layers of GI tract
- Mucosa
- submucosa
- muscularis externa
- serosa/adventitia
What makes up the mucosa? Which section is innervated by the Messeiner Plexus?
Epithelium Lamina propria Muscularis mucosa - this layer of SM that is the origin of glands - keeps surface of epithelium clean - innervated by Messeiner plexus
What makes up the submucosa? Which two places do submucosal glands only occur?
denser CT large BVs nerve plexus lymphatic nodules scattered lymphoid cells
- Esophagus (esophageal glands)
- Duodenum (Brunner’s glands)
What makes up the muscularis externa? Fxn? Which nerve plexus is found between the two layers of m?
Inner circular smooth muscle
Outer longitudinal smooth muscle
Nerve plexus
- fxns in peristalsis and churning of lumen contents
- Auerbach’s/Myenteric plexus
What makes up the serosa/adventitia?
Outer covering of squamous epithelial cells (mesothelium)
Connective tissue
How does digestive system protect itself from autodigestion?
Except for esophagus and anal regions:
GI tract is lined by mucous that protects inner layers of epi from harsh acidic states/enzymes
Also, pancrease secrete zymogens (inactive enzymes)
How does digestive system protect itself from pathogenic bacterial invasion?
- Peyer’s patch: immune surveillance of intestinal lumen + generation of immune response w/in mucosa
- macrophages, DCs, B+T cells are found here - M cells: cover Peyer’s patches
- Ag uptake cells
- presents Ag to lymphocytes and macrophages
Why can reflux cause a burning sensation (heartburn) in the lower esophagus?
the esophagus lacks a thick mucous covering (it does have mucosa glands to give some lubrication)
Type of muscle seen at each level:
Upper 1/3 esophagus
Middle 1/3
Lower 1/3
Upper 1/3 : skeletal muscle
Middle 1/3: mix skeletal + SM
Lower 1/3: SM
normal histology of the esophagus including the epithelial transition at the junction with the stomach.
esophagus: stratified squamous epi, esophageal glands, thick muscularis mucosa
gastroesophageal jxn:
transition from stratified squamous → intestinal simple columnar
What do neuroendocrine cells in the gland region of the stomach secrete?
Gastrin
- help increase HCl release in stomach
Which part of the stomach secretes mucus?
cardia
fundus
pylorus
which part of the stomach secretes acid and peptic digestive products and mucus?
fundus (main body)
which part of the stomach has a large preponderance of endocrine cells that secrete gastrin?
pylorus
Name what they secrete: A cells D cells E cells G cells
A cells - glucAgon
D cells - somaDostaDin
E cells - sErotonin
G cells - Gastrin (in pyloric region)
- all are found in stomach and small intestine
- D and E are also found in large intestines
Ulceration are commonly due to _______.
Zollinger-Ellinson syndrome is due to ______
H. pylori infxn
Excessive secretion of gastrin → overproduction of HCl by parietal cells → inadequate neutralization in small intestin → duodenal ulcers
Which has the best developed plicae circularis?
Duodenum
Jejunum
Ileum
Jejunum
also has villi decreasing distally
Which has the most goblet cells and lymphatic tissues?
Duodenum
Jejunum
Ileum
Ileum
- need most protection/lube
- need good immune response 4 poo
98% of the pancreas is dedicated to (pick on) exocrine/endocrine fxn?
Exocrine
it also contains islet of langherhans for glucagon + insulin
Efferent fibers of the myenteric plexus innervate the ___
muscularis externa
Characteristics of the large intestine
smooth lacks villi/plicae numerous straight tubular glands/crypts epithelial layer - mucous prod - absorptive removal of H2O + salt - [ ] fecal material
structure of intestinal villus and role in nutrient abs
Intestinal villi: contains loose lamina propria w/ small blood vessels and capillaries, lymphocytes, small lymphatic spaces (that join larger lymphatic vessel)
- nutrients taken up by capillaries will go to hepatic portal system
In the crypts of lieberkuhn, stem cells are found in the lower 1/3 of the crypt at the neck. What do they give rise to?
mucous cells
enterocytes
paneth cells
(remember that paneth cells have eosinophilic granules that contain defensins, lysozymes, and phospholipase)
2 enzymes synthesized by pancreas straight into active form
amylase
ribonuclease
Which part of the gut contains crypts of lieberkuhn?
duodenum
jejunum
ileum
colon
