Gastroenterology II Flashcards
(27 cards)
What are the 3 major functions of the stomach?
- Storage of food
- Food digestion
- Regulation of GI function
What features of the stomach are designed specifically for storage of food?
- Chyme of formation
- expandable
- rugae (folds are all temporary, when expand, they go away)
- mucosal adn submucosal folds
Which molecules are secreted by the stomach to aid in food digestion?
HCl (creates low pH)
pepsin
lipase
What are the four anatomical regions of the stomach?
What are the 3 histological regions of the stomach? What are the glands associated with these regions?
- Anatomical
- cardia
- fundus
- body
- pylorus
- Histological
- cardiac
- cardiac glands
- entering food, preventing acid reflux
- cardiac glands
- fundic
- fundic glands
- most abundant, throughout stomach
- fundic glands
- pyloric
- pyloric glands
- modifying chyme as it enters the small intestine, making it less acidic
- pyloric glands
- cardiac
What are the layers of the stomach? Include important characteristics of each
- Mucosa
- very thick
- Submucosa
- dense irregular connective tissue
- meissner’s plexus
- Muscularis externa
- inner oblique layer
- middle circular layer
- outer longitudal layer
- auerbach’s plexus
- Serosa
- connective tissue
- mesothelium
What is the difference between the musculars externa of the stomach and that of the rest of the alimenary canal?
it has 3 layers, whereas the rest only has 2
the additional layer is the oblique layer, that helps to push food through it since it is a weird, pear shape rather than a tube
What type of cells make up the surface epithelium of the gastric mucosa?
What are unique characteristics of this type of cell?
What is the name for dips in the epithelium?
- surface mucous cell – simple columnar (few microvilli) –
- protects the whole stomach from HCl, stuffed with insoluble mucus rich in HCO3- (PGE2- dependent)
- Gastric pits
Why do NSAIDs weaken the stomach lining?
decreases production prostaglandin E, which weakens secretion of bicarbonae, so the layer becomes less alkaline so it is easier for HCl to digest through
also, they can penetrate through the mucosa and act directly on the epithelial cells
What layer of the stomach contain the 3 types of glands?
What else is located in this layer?
lamina propria
loose connective tissue with immune components
What are the regions of the fundic glands?
What type of cells compose fundic glands?
- Isthmus
- Apical portion
- Neck
- principal piece
- Base
- adjacent to m. mucosae
- Cell types
- parietal cell
- gastric chief cell
- mucous neck cell
- progenitor cell
- enteroendocrine cell
Where are parietal cells located within the fundic gland?
shape?
cell characteristics?
what do they secrete?
Difference between actively secretign cell and a resting cell?
- neck and base of fundic gland
- large, pyramidal
- numerous mitochondria
- stain with eosin
- secrete
- HCl
- intrinsic factor (glycoprotein that binds vitamin B12)
- apicla part of cell
- actively secreting cell
- intracellular canaliculi with microvilli
- increases membrane, so can secrete more HCl
- intracellular canaliculi with microvilli
- resting cell
- canaliculi become shallow and microvilli are inside cell
- tubulovesicular system: membrane storage
- actively secreting cell
What are the two consequences caused by a deficiency in parietal cells?
what is the chief cause of this?
- Gastritis
- increased pH of chyme, won’t be able to digest stuff
- Pernicious Anemia
- no intrinsic factor, can’t absorb B12 which is required for hemoglobin formation
caused: autoimmunity in patients with chronic gastritis
What can be the result when the epithelial protective barrier is impaired?
Why does this happen?
If left untreated, what can happen?
gastric ulcer
HCl destroys cells
if left untreated can penetrate deep and cause peritonitis
Where are gastric chief cells located within the fundic glands?
what do they secrete?
cell characteristics?
- location
- base of gland
- secrete
- pepsinogen
- pepsinogen –> pepsin
- Autocatalytic (HCl)
- by pepsin
- pepsinogen
- Cell structure
- abundant RER
- protein synthesis
- basophilia
- apical secretory granules
- abundant RER
Where are mucous neck cells located within the fundic gland?
what do they secrete?
how does this suppor the fundic gland?
cell characteristics?
- location
- neck of gland
- secrete
- soluble mucus
- allows stuff to flow out of the fundic gland
- cell structure
- small cell
- heterochromatic nucleus
- mucinogen granules
- “frothy” cytoplasm
Where are enteroendocrine cells located within the fundic gland?
What do they secrete?
Cell characteristics?
- location
- mostly at base
- need to be near capillaries
- mostly at base
- secrete
- GI hormones
- gastrin (G cells), ghrelin
- somatostatin (D cells)
- Histamine
- enterochromaffin-like cells
- GI hormones
- Cell structure
- numerous secretory granules
- at base of cell
- numerous secretory granules
How many different types of hormones can heach enteroendocrine cells make?
they can only make one hormone, even though there are several horomone enteroendocine cells are capable of producing
- Which hormone stimulates production of HCl by the parietal cells
- Which type of cell is it produced by?
- Which hormone is the hunger hormone?
- Which type of cell is it produced by?
- Which two horomones slows down the production of HCl?
- Which type of cell is it produced by?
- Gastrin (G cells)
- ghrelin (GR cells)
- Somatostatin (D cells) and Histamine (Enterochromffin-like cells)
Where are enterochromafin-like cells located within the fundic gland?
What do they secrete?
What are they stimulated by?
What are the inhibitied by?
What is their function?
- location
- near parietal cells
- secrete
- hitsamine
- bind to H2 receptors on parietal cells & stimulate to make HCl
- hitsamine
- stimulated by
- gastin
- vagal stimulation
- M1 receptors
- inhibited by
- somatostatin
- Function
- stimulate HCl secretion by parietal cells
Draw this pathway
Where are progenitor cells located within the fundic gland?
Which cell types can they differentiate into?
How long do these different cell types last?
Function?
- location
- isthmus
- precursors for
- surface mucous cells
- short lifespan: 3-5 days
- gland cells
- long lifespan: 6-8 months
- surface mucous cells
- function
- mitotic figures
What is the pathalogic effect when a tumor is formed from gastrin secreting enteroendocrine cells?
severe ulcers throughout GI tract
What type of tissue makes up the cardiac stomach?
Where are glands distributed in this space?
What is the major function of cardiac glands?
Cardiac cel characteristics?
- Shallow gastric pits
- location
- near esophageal orifice
- function
- productin of mucus
- protection against acid reflux
- Cell characterisitics
- brached tubular glands
- mucous glands
What type of tissue makes up the pyloric stomach?
Where are glands distributed in this space?
What is the major function of pyloric glands?
Cell characteristics?
- Deep gastric pits
- gland location
- pyloric antrum
- function
- production of mucus
- structure
- branched coiled tubular
- mucous glands
