GI-Salivary Secretions Flashcards
What is the primary control of the secretion of the salivary glands?
PSNS
What enzyme of saliva initiates the digestion of carbs?
a-amylase
What kind of bonds does a-amylase cleave?
internal a-1,4-glycosidic bonds
What enzyme of salivary secretions begins the digestion of triglycerides?
Lingual Lipase
What is released by the salivary gland with the function of binding to Vitamin B12 (cobalamin) in the acid environment of the stomach?
Haptocorrin
What is secreted in the saliva as an immunological response against bacteria and viruses?
IgA
What is secreted in the saliva to chelate iron?
Lactoferrin
What is the largest of the salivary glands?
Parotid
What cells make up the Parotid gland and what do they produce large amounts of?
Serous cells; H2O, HCO3-, and enzymes
What percentage of the total volume of saliva does the Parotid gland produce at rest flow?
25%
What percentage of the total volume of saliva does the Parotid gland produce when stimulated?
80%
What kind of gland is the Submandibular gland considered, based on the type of fluid produced?
Mixed; mucus and serous
What is the major component of the Submandibular gland, that when at rest accounts for the largest component of salivary volume (~70%)
Mucus
What kind of gland is the Sublingual gland considered, based on the type of fluid produced?
Primarily mucus, with a small serous component
Where can smaller salivary glands be found?
tongue, lips, and palate
The Acinus of the salivary secretory unit is the round portion that is surround by Acinar Cell that produce …
the saliva and mucus
What surrounds the Acinar Cells that can aid in the expulsion of freshly secreted saliva out of the Acinus and into the Intercalated and Striated Duct Regions?
Myoepithelial cells
The efferent impulses of the PSNS are distributed by what two nerves and mediated by what respective receptors?
Facial VII (muscarinic) and Glossopharyngeal IX (cholinergic)
The SNS also stimulates the production of saliva, with its effects mediated through what receptors?
B-adrenergic receptors
Higher Sympathetic outflow (during low PSNS stim.) stimulates … secretions, while also stimulating vaso-constiction thus reducing the … secretions.
mucus; serous
Conditioned stimuli, smell, taste, chewing, and nausea stimulate … in the Medulla Oblongata?
Nuclei Salvatorii
In the PSNS stimulation through CN VII and IX, what NT is released?
ACh
ACh stimulates the salivary gland to increase its level of … that leads to an increase in cell Ca2+.
IP3
The increased cell Ca2+ in the salivary gland stimulates what 5 things?
vasodilation, increased metabolism, myoepithelial cell contraction, increased secretion, and cell growth
The higher stimuli trigger a Sympathetic Mediated response through the Thoracic Spinal Nerves, releasing ….(NT) to ….
ACh –> Superior Cervical Ganglion
What NT does the SCG release?
NE
What does NE increase in the salivary gland cell, that leads to an increase cell Ca2+?
cAMP
What is another salivary gland regulatory mechanism that is released by the postganglionic fiber?
VIP (vasoactive intestinal peptide)
What does VIP mediate?
vasodilation by increasing BF and volume secretion
[K+] is higher in …
saliva
Salivary Na+ and Cl- … than plasma.
less
Salivary HCO3- is … than plasma except at LOW flow rates.
greater
The ionic gradients of the Acinar Cells are set up by a basolateral …
Na/K-ATPase
Na+ cycles inward in the Acinar Cell down the concentration gradient by cotransport with …
Cl-
K+ diffuses out of the Acinar Cell down its electrochemical gradient, along with … across what membrane?
HCO3-; apical
As the salivary secretion does past the Duct Cells what is reabsorbed?
Na+ and Cl-
As the salivary secretion does past the Duct Cells what is secreted?
smaller amount of K+ and HCO3-
The salivary ductal solution is … due to its impermeability to water.
hypotonic
As flow past the Salivary Duct Cells increases, [Na+] and [Cl-] in the salivary lumen …
increase
As flow past the Salivary Duct Cells increases, [K+] in the salivary lumen …
decreases slightly
As flow past the Salivary Duct Cells increases, [HCO3-] in the salivary lumen …
increases because its secretion is increased by the same stimuli that increases the flow rate
Salivary flow rate has what affect on pH?
increases because of the increase in HCO3-