010714 biochemical and nutrition for stomach Flashcards
components of saliva
salivary gland secretions
microorganism products
soluble food products
purpose of saliva
lubrication digest food and enzymatic cleavage growth factors for epithelial cells neutralizes bacterial acids mediates taste sensations provides defense against bacterial pathogens
primary secretion of salivary gland has
ptyalin (alpha amylase)
mucus
extracellular fluid (ions)
what does the saliva contain for bacterial defense?
lysozyme (kills gram positive bacteria by cleaving beta 1-4 linkages between NAM and NAG in peptidoglycan)
peroxidase lactoferrin (binds iron and prevents bacterial growth) IgA defensins mucins
mucin’s role
lubricates
antimicrobial
saliva’s ionic content is high in what and low in what
high in bicarbonate–it neutralizes bacterial acids
low in Na and Cl
cephalic phase of gastric secretion
parasympathetics excite pepsin and acid production
gastric phase of gastric secretion
local nervous secretory reflexes
vagal reflexes
gastrin-histamine stimulation
intestinal phase of gastric secretion
nervous mechanisms
hormonal mechanisms
stomach’s acid secretion is regulated how?
vagus nerve releases Ach and GRP
what are ACh’s effects?
stimulates secretion of ECL cell histamine and parietal cell HCl
inhibits secretion of D cell somatostatin
What are GRP’s effects
stimulates secretion of G cell gastrin
control of D cells occurs through?
somatostatin secretion is stimulated by HCl and inhibited by ACh
somatostatin’s effects?
inhibits secretion of G cell gastrin, ECL cell histamine, and parietal cell HCl
gastrin secretion is controlled how?
stimulated by nerve’s GRP
inhibited by somatostatin
