Saliva Flashcards
What are the 3 major exocrine salivary glands?
1) Parotid
2) Submandibular
3) Sublingual
What gland produces the most secretion?
sub mandibular
what gland produces the least secretion?
Sub lingual
What is submandibular secretion?
Serous-Mucin
What is Parotid secretion
Serous
What is Sub lingual secretion?
Mucin
Where is primary secretion?
In acini by acinar cells
Where does secretion pass?
Acinus> intercalated ducts> striated ducts>excretory duct
What is primary secreted saliva?
watery, inorganic ions and enzymes - similar to plasma
how do Columnar cells modify primary to Secondary secretion?
in striated duct it’s modified via secretion/absorption
What is around acini?
layer of smooth muscle made from myoepithelial cells
What does smooth muscle around acini do?
alter flow rate to help secretion of saliva via contraction/relaxation
Are K+ and HCO3- concs. higher in Saliva than plasma?
YES
Are Na+ and Cl- concs. lower in Saliva than plasma?
yes
What are reabsorbed from striated duct?
Na+ and Cl-
What are secreted into lumen of striated duct?
K+ and HCO3-
What does striated ductal epithelium have?
Low permeability to water so more ions reabsorbed
What is secondary secretion?
Hypotonic
What is primary secretion?
Isotonic
What cells allow transport?
Columnar cell
How do Na+ cells enter columnar cell from lumen via Apical membrane?
via Na+ channel and Na/H exchanger
what is the apical membrane?
layer of plasma membrane towards lumen
How does Na+ exit columnar cell via Basolateral membrane?
Via Na/K pump, 3 Na removed and 2K pump in
How does Cl- enter columnar cell via apical membrane
via Cl/HC03- exchanger
How does HCO3- secretion out of columnar cell occur?
Via apical CL/HC03- exchanger into lumen
How does columnar cell uptake K+?
Na/K pump at basolateral membrane
How does K+ secrete into lumen?
Apical K-H exchanger
Evidence for 2 stage secretion ?
Acinar micropuncture
Poly-lysine injection- stop 2ndary reabsorp. so saliva is primary fluid now
flow rate curves
What stimulates flow rate change?
Aldosterone
What happens at low flow rates?
more time for secondary ductal modification
What happens at high flow rates?
less time so composition reaches primary secretion
How is Salivary secretion controlled and increased?
ANS- parasymp. and Sympathetic
How does parasympathetic increase saliva secretion?
Acetylcholine - contract myoepithelial cells around acinus
What does release of VIP (Vasoactive intestinal peptide) do?
vasodilation so inc. blood flow to Salivary glands
What do all salivary glands have ?
acinar cells
What do striated epithelium ducts have?
columnar cells for transport
How does Sympathetic increase saliva secretion?
Adrenaline/noradrenaline- contraction of myoepithelial
What do Na+ depleted animals have?
Increased Aldosterone- Na+ retention
What stimulates ductal transport?
Mineralocorticoids e.g. aldosterone
