Phgy 210 – Gastric System 6

Phgy 210 – Gastric System 6 - 19:48...

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Phgy 210 – Gastric System 6 19:48 Secretion is an active, energy dependent and blood flow dependent process,  resulting in the release of a fluid containing ions and a variety of enzymes : Amylases Proteases Lipases Pattern of regulation : Nervous (ANS)  Hormonal (gut peptides) As you go down, less ANS involvement and more hormonal involvement. Major salivary glands : Parotid gland o Serous fluid secretion Sublingual gland o Mucous fluid secretion Submandigular gland o Mixed secretion Saliva : 0.5-1.5L/day. Mostly in association with meals. The ionic composition is  basically Na+, K+, Cl-, HCO3-. It is, however, hypotonic. It is the only  gastrointestinal secretion that is hypotonic. The pH is 6.5 to 7. This is the optimal  pH for the major enzyme in saliva, ptyalin (Starch   Maltose). Also lots of mucin (lubricates the bolus and facilitates speech). Are there lipases?  Maybe a minute amount, but nothing physiologically relevant. Maybe in infants  though. Some lysozymes are present as well. Again, the regulation is mostly by ANS : Parasympathetic (Most important)   ACh(M) on salivary glands. This will  cause an increase in secretion and vasodilation. o Note that M receptors can be inhibited by atropine. Sympathetic  o Vasoconstriction. Maybe something else, but it is unknown now…Not  physiologically important, however. Salivary secretion is always triggered by reflexes :
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This note was uploaded on 04/26/2011 for the course PHGY 210 taught by Professor Trippenbach during the Spring '08 term at McGill.

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Phgy 210 – Gastric System 6 - 19:48...

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