Salivary, gastric and pancreatic secretions Flashcards
Describe the stimulation of salivation
Set off by taste, smell and touch + chewing
Cholinergic (ACh), adrenergic (NA) and peptidergic stimulation
Parasympathetic stimulation via corda lingua nerve causes increased fluid secretion, oxygen consumption and blood flow
Sympathetic stimulation causes initial vasoconstriction, then vasodilation with a viscous protein rich secretion via B-adrenergic stimulation
What are the stages of saliva formation?
Isotonic primary fluid, similar to plasma in electrolyte composition
Modification in ductal sysem, NaCl removed, protons and HCO3- secreted
What drives water and protein secretion in saliva?
Sympathetic action via Na+; parasympathetic action via VIP (vasoactive intestinal peptide) and ACh
What are the physiological changes that occur in old age that lead to hyposalivation
reflexes impulse transmission hormones blood flow sensory stimuli
gland atrophy -> hypofunction
What is IF
Intrinsic factor, glycoprotein that forms a complex with vit B12 that helps its absorption
What are the cells that make up the villi found in the stomach
superficial epithelial cells
mucous neck cells
stem cells (replace dead cells)
parietal cells (secretes acid)
chief cells (synthesis and storage of pepsinogen)
endocrine cells (secrete gastrin, acts near parietal cells)
What is the purpose of the mucous gel that lines the stomach?
To protect tissues from the low pH of the lumen of the stomach
What produces the energy required for gastric acid secretion?
Oxytinic glands
How is gastrin involved in gastric acid secretion?
Food stimulates G cells, which release gastrin
Gastrin enters blood stream and acts on ECL cells, which release histamine
Histamine acts on parietal cells which then produce the acid.
How do you treat a patient with a stomach ulcer to reduce their gastric acid secretion?
Use a proton pump inhibitor usch as omeprazole
How does omeprazole work
Forms disulfide link w/ H+-K+ ATPase;
inhibits gastric HCl
used to treat peptic ulcer and reflux oesophagitis
How is the antral parietal cell stimulated?
Antral G cell stimulated via local ENS, vasovagal reflexes + by peptides + AAs;
then it produces gastrin which activates the ECL cell which produces histamine which activates the parietal cell
What effect does fat in the duodenum have on gastric acid production?
It decreases it
Describe pancreatic NaCl secretion
Paracellular movement of Na from interstitial to acinar lumen. Na-K-Cl co transporter moves the three ions in to the cell; then the Cl diffuses into acinar lumen; then the Na used to bring in the Cl is pumped out, while K is pumped in by the same protein; this increases the conc of Na+ in the interstitial fluid so more will diffuse into acinar lumen. Then the excess K now in the cell is moved back into interstitial
