T1 - Salivary and gastric secretions Flashcards
what type of glands are the salivary and gastric glands?
exocrine
what are the main endocrine cells in the stomach and SI?
enteroendocrine cells
what is the volume and tonicity of salivary secretions?
high volume and hypotonic
where does the duct from the parotid gland enter the oral cavity?
above the second molar
what type of secretions does the parotid gland release and what enzyme does it contain?
serous/water secretions that contains salivary amylase
what type of secretions does the submandibular gland produce?
mixed serous and mucus secretions
what type of secretions does the sublingual gland produce?
viscous/thicker secretions for lubrication
which two glands produce 90% of saliva?
parotid and sub mandibular
what are five substances found in saliva and what do they do?
1) alpha amylase - digests starches by hydrolysis 1,4 glycosidic bonds
2) lysozyme - hydrolyses peptidoglycan in the wall of gram negative bacteria
3) lingual lipase - initiates hydrolysis of triglycerides and is active at an acidic pH
4) lactoferrin - antimicrobial properties and chelates iron to stop microbes multiplying
5) kalikrein - converts plasma protein alpha 2 globulin to bradykinin
what molecule is released when constriction of salivary glands is required?
kallikrein which converts plasma alpha 2 globulin to bradykinin which causes vasoconstriction
which cells secrete the predominant components of saliva?
acinar cells
what cells surround the acinar cells and what is their function?
myoepithelial cells which contract to push secreted contents into the duct
how is hypotonic saliva produced?
- ion exchange: K+ and HCO3- in and NaCl out
- NKCC1 brings Na, Cl and K in through acinar cells
- Na is exchanged out for K+ in
- Cl- is exchanged out for HCO3-
what happens to proportions of ions in the saliva when secretion increases (Na, HCO3-, CL and K)
- HCO3- and K+ stay the same
- NaCl concentrations increase (still stays hypotonic)
which cranial nerves stimulate salivary secretion and via which glands?
- cranial nerve VII (facial) to the sublingual and submandibular
- cranial nerve IX (glossopharyngeal) to parotid gland
what effect does parasympathetic input have on saliva flow?
- increases amylase and mucin containing watery saliva
- vasodilation
- increased saliva flow
what effect does sympathetic input have on saliva production and what is this via?
- inhibits saliva production
- signals via the superior cervical ganglion
- vasoconstriction
what is the effect of sympathetic input on amylase content on the saliva?
- increased amylase content but decreased overall saliva production
what is stoorgrens syndrome?
autoimmune condition that destroys exocrine glands
- reduced saliva production and dry eyes and mouth
what is xerostomia?
lack of saliva production, decreased lubrication and hard to speak/swallow
what are the three exocrine gland cells in the gastric pits?
1) mucus neck cells
2) chief cells
3) parietal cells
what does each exocrine gland cell release?
mucus neck cells release mucus
parietal cells release Hcl and IF
chied cells release pepsinogen in adults and rennin/gastric lipase in neonates
what are the endocrine cells of the gastric glands and what do they secrete?
- G cells secrete gastrin
- D cells secrete somatostain
- enterochromaffin cells secrete histamine
what does gastrin cause and what is it stimulated by?
causes gastric digestion
- stimulated by distention of stomach and presence of partially digested fragments
