Stomach Secretions Flashcards
What are the digestive functions of saliva?
moisten and lubricate diet, buffering activity, add water to diet to make fluid more isotonic, being starch and fat digestion
How does secretin effect saliva?
it stimulates the addition of Na, K, and removal of Cl from saliva
What is the esophageal part of the stomach considered?
non-glandular
What type of epithelium is in the esophageal part of the stomach?
stratified squamous epithelium
What does the esophageal part of the stomach extend to in the horse?
the margo plicatus
What are the glandular, non-acid secreting parts of the stomach?
the cardia and pyloric regions
What do the cells of the cardia make?
mucous
What do the glands of the pyloric region make?
mucous
What do the enteroendcrine cells of the pyloric region secrete?
gastrin
What is the glandular, acid secreting part of the stomach?
the fundic portion
What types of cells are located in the fundic portion of the stomach?
mucous secreting cells, parietal cells, chief cells, enteroendocrine cells
What do parietal cells make?
HCl and intrinsic factor
What do chief cells make?
pesinogen, rennin, and other enzymes
What do enteroendocrine cells release?
various endocrine and paracrine hormones
Where are mucous cells found?
in gastric puts interspersed throughout columnar epithelium of gastric glands
What is the function of mucous in the stomach?
protect the stomach from acids and enzymes
What is intrinsic factor vital for?
the absorption of vitamin B12
What is pepsinogen?
a proteolytic enzyme pre-cursor
What happens when pepsinogen comes in contact with acid made by parietal cells?
it is cleaved to form pepsin
What does peptin do?
cleaves proteins at aromatic amino acids
What is the secretion of pepsinogen stimulated by?
gastrin
Where are entero-endocrine cells found?
at the base of gastric glands in mostly fundus an pyloric regions
What can entero-endocrine cells make?
glucagon, somatostatin, histamine
What are G-cells?
specialized enteroendocrine cells found in the pyloric stomach area that release gastrin
What are G-cells stimulated by?
rising pH of chyme, stretch of stomach, vagal stimulation, and peptides/amino acids stimulate chemoreceptors within the mucosa
What is the function of parietal cells aside from making HCl and intrinsic factor?
transfer Cl into the lumen of the gastric glands and remove Na and K from the gastric gland lumen fluid making the SID more negative and lowering the pH
During active acid secretion from the stomach, what is the pH of the blood?
alkaline
What stimulates acid secretion?
vagus nerves, gastrin, and histamine
What causes the corteex to activate vagal efferent pathways to stimulate acid secretion?
thought, smell, or taste of food
What turns on histamine release?
gastrin
How does histamine stimulate acid secretion?
it acts on H2 receptors on parietal cells to simulate acid secretion
What do gastrin and histamine raise the level of before acid production?
intracellylar cyclic AMP levels
What suppresses gastrin production?
acid
What hormones have a minor role in inhibiting acid production?
VIP, GIP, Eteroglucagon, CCK-PKZ
Since secretin does not inhibit acid production, what does it do?
it works on the pancreas, Brunner’s glands, and salivary glands to enhance alkaline secretions production
Where is prostaglandin E1 and 2 and PGI2 produced by?
mucosal cells of the stomach and intestine
What is prostaglandin E1 and 2 and PGI2 produced in response to?
excessively low pH and damage to mucosa
What do prostaglandin E1 and 2 and PGI2 do?
increases mucus production, decrease H2 mediated acid secretion, inhibits gastrin secretion, increases blood flow to help renew and repair cells
How do NSAIDs cause ulcers?
they block PGE1 and PGI2 to decrease mucus production, increase acid production, and decrease blood flow to damaged mucosa
What are the type of cells that line the horses stomach?
non-glandular stratified squamous epithelium and glandular epithelium
What does the non-glandular epithelium of the horse’s stomach get protection from?
prostaglandin E and I2
What does the glandular eptihelium of the horse’s stomach get protection from?
it secretes a mucus-Na bicarbonate layer that serves to protect the stomach lining by preventing acid from getting direct contact with it
What is special about acid production in horses?
it happens continuosly
If you were to find horse bots, where in the stomach would you find them?
in the non glandular part
Where are stomach ulcers usually found in swine?
in the cardia of the stomach
What are common symptoms associated with stomach ulcers in swine?
anemia and melena (dark stool)
What nutritional factors can lead to stomach ulcers in swine?
finely ground feed (particularily corn), restricted availability of water or feedm low vitamin E and selenium
What bacteria is associated with ulcers across species?
helicobacter
