Gastrointestinal Flashcards
funtions of alimentary mucosa?
1) secertion
2) absorption
3) barrier
4) immunologic
basic organization of alimentary canal layers? (deep to superficial)
1) mucosa thin layer of muscle 2) submucosa 3) muscularis externa 4) serosa
3 projections in mucosa?
1) plicae cicularis = submucosal folds
2) villi = mucosal projections
3) microvilla =projections of apical surface of cells
glycocalyx found on what type of mucosa projection?
microvilla
*glycocalyx is the glycoprotein layer on the apical surface of absorptive cells
extramural galnds deliver to ____ only?
what glands are scattered throughout canal?
small intestine
mucosal and submucosal glands
peyers patch?
diffuse lymph tissue/nodules found in SI (type of GALT)
muscluaris externus muslces?
inner=tighti=circle/spiral
outer=loose=length/shorten
*together responsible for peristalsis
*separated by C.T. layer that houses the myenteric plexus from enteric nervous system
enteric nervous system
- Part 1 in submucosa =meissner’s plexus
* Part 2 in muscularis externa in the CT between the two layers of muscle = myenteric plexus
List the 5 sphincters
1) pharyngoesophageal sphincter =prents entry of air into esophagus
2) inferior esophageal sphincter = prevents gastric reflux
3) pyloric = junction of stomach and duodenum
4) ileocecal = junction of small and large intestine
5) internal anal sphincter = surrounds anal canal
adventitia
point of digestive tract attachment for the portions that are directly affixed to the cavity wall by CT
serosa is a serous membrane consisting of ______?
mesothelial layer that is continuous with mesentary of abdominal cavity
mucosa lining the esophagus is special and different from skin how?
it is NON-keratinized stratified squamous epithelium with no cross-linking that allows for expansion as food passes
what are the 3 gastric glands in the stomach? what do they secret?
- cardiac and pyloric secrete mucous to protect stomach epithelium
- fundic glands secrete most digestive products
3 parts of stomach?
1) cardiac = near esophageal oriface
2) pyloric = junction of stomach and SI
3) fundic region = largest, body of stomach
stomach is lined by what type of cell? what makes them special?
simple columnar epithelium
*have surface mucous cells that have LARGE apical cup of mucinogen granules that release bicarbonate and potassium to protect epithelium from low pH
what does the parietal, chief and enteroendocrine cells of stomach do?
- parietal = scattered, produce HCL and intrinsic factors
- cheif cells= DEEP, pepsin
- enteroendocrine cells= gastrin, bile and sense whats (endo and exo) happening in stomach digestively
what is super special about parietal cells?
they have an extensive intracellular canalicular system to increase surface area with numerous microvilli to facilitate proton pump activity (scattered, produce HCL and intrinsic factors)
5 types of cells in intestinal epithelium?
1) entercytes= absorption
2) goblet= mucin secretion
3) paneth cells= maintain mucosal innate immunity
4) enteroendocrine= produce paracrine and endocrine hormones (gastrin, bile, sense what is happening in digestive tract)
5) M cells= cover lymph nodules
explain M cells
- facilitate passage of microorganisms to underlying lymph tissue
- envaginated at basament lamina to allow lymphocytes to enter closer to lumen
- M cell sourronds lymph tissue
- **have smooth surface compared to microvilli
crypts of lieberkuhn
glands found in mucosa of LI, house stem cells that in base of gland and repopulate the mucosa every 5 days
principle function of large intestine?
absorption of electrolytes and water; elimination of waste
*very little nutrient re-absorption
what cell does the LI lack that the SI has?
paneth cells= maintein immunity, secrete ani-microbial lysozymes and alpha-defensins
What is the bulk of the cells found in pancreas? what do they do?
B (beta) cells= control plasma glucose levels by releasing insulin = ENDOCRINE function
what is the endocrine function of pancreas and the 3 cells associated with it?
*regulate blood glucose
alpha= secrete glucagon
beta= secrete insulin
delta= secrete somatostatin
how do you ID the exocrine and endocrine parts of pancreas? Islets are exo or endo?
LARGE dark purple areas= exocrine light small (round) purple areas= endocrine= **islets of Langerhan**
explain acinar cells, intercalated duct, cetroacinar cells and pancreatic duct?
- Exocrine function of pancreas to release digestive enzymes
- acinar cells are TRIANGULAR and surround intercalated duct system
- intercalated ducts drain into main pancreatic ducts that drain into duodenum
- centriacinar cells are FLAT cells that mark the beginning of intercalated ducts, considered to be part of acinar cells
hepatopancreatic ampulla and sphincter?
where the pancreas empties into the duodenum and controls bile flow
what layer of tissue is the gallbladder missing?
submucosa
*stright from mucosa to muscularis externa
what increases and decreases bile flow?
- increase= hormones cholecystokinin, gastrin, motilin to aid digestion
- decrease= steroid hormones
- released by enteroendocrine cells
what is the smallest branch of biliary tree?
bile canaliculi
cholangiocytes
monitor bile flow and regulate bile content via PRIMARY cilia that acts as mechonosensor
biliary tree
from hepatocytes to gallbladder to intestine
lots of catalase found?
in hepatocytes and peroxisomes to dergade hydrogen peroxide
kupffer cells
are phagocyte cells that monitor sinusoides that receive blood
