Saliva 1 - Basics Flashcards
What are the functions of saliva?
Maintain oral health (Lactoferrin, Peroxidase, Lysozyme)
Mineralisation (calcium ions released, increases pH (bicarbonate))
Lubrication (speech and swallowing)
Digestive function (Amylase & Lipase)
Control of taste & temperature dilution occurs (Solvation leads to taste)
What is the composition of saliva?
Submandibular – sero-mucin – 70%
Parotid – Serous - 25 %
Sublingual – Mucin / mucus – 5%
Total 1.5L per day
Whats the pathway of saliva?
Acinus to intercalated duct to striated duct to excretory duct.
What is the acinus comprised of?
Acinar cells present.
Myoepitheial cells
What is the striated comprised of?
Columnar cells present
Modifies primary secretion
Describe the first stage of 2 stage secretion
From acini (sodium, potassium, chloride, carbonate ions and water are added) to the duct
Describe the second stage of 2 stage secretion
Striated ducts remove sodium and chloride ions, add potassium and bicarbonate
Saliva solution goes from isotonic to hypotonic
Describe salivary ion transport
Na+ enters cell via ENaC on Apical & Na+ / H+ exchanger
Na+ exits cell on Basolateral via Na+ / K+ pump
Cl- enters cell via Cl- /HCO3- exchanger on Apical
Cl- exits cells via channels on Basolateral and Apical
Exits cell via Cl- / HCO3- exchanger on apical
Basolateral transfer is not well understood
K+ enters cell via sodium potassium pump on Basolateral membrane
K+ exits cell by K+ /H+ Exchanger on Apical membrane
How does salivary ion concentration increase with flow rate?
Na+ conc. increases
Cl- conc. increases
HCO3- conc. increases due to inc. in metabolism
K+ conc. Decreases
What is the evidence for modification of saliva composition?
Micropuncture of Acinar & intercalated ducts
Poly-lysine injection to poison duct means no Secondary secretion = saliva like primary
Flow rate curves
N.B. Flow rate affects ionic comp. of saliva as more/ less time for reabsorption/secretion
Describe the involvement of higher brain centres salivary flow
Both sympathetic and parasympathetic stimulation lead to salivation
Parasympathetic (Acetylcholine) Myoepithelial cells
VIP released (cause vasodilation Myoepithelial cells)
Secretion is watery
Sympathetic Adrenaline + Noradrenaline released
Secretion is mucin rich/ sticky / enzymes
N.B. think of this as – when you are nervous, your mouth goes dry ( sympathetic sticky saliva)
What factors increase salivary flow?
Thought of food/ smell of food
Food in the mouth
Water brash prior to sickness
What are the effects of aldosterone?
Na+ in blood high means aldosterone levels are low in blood therefore Na+ high in saliva
Na+ in blood low means aldosterone levels are high in blood therefore Na+ low in saliva
N.B people with Addison’s disease have low aldosterone secretion Na+ concentration in saliva increases
