Saliva

Question 1

What are the functions of saliva?

Answer 1

Maintenance of oral hygiene
Maintain mineralisation of teeth
Lubrication - speaking and swallowing - mucin
Digestive function - amylase and lipase
Solvation - enables one to taste foodstuffs

Question 2

What does the submandibular gland contain?

Answer 2

70% seromucin

Question 3

What does the sublingual gland contain?

Answer 3

5% mucin

Question 4

What does the parotid gland contain?

Answer 4

25% serous

Question 5

What is the pathway of saliva from the acinus?

Answer 5

Acinus - intercalated ducts - striated ducts - excretory ducts

Question 6

What ions concentrations are higher in saliva than in plasma?

Answer 6

K+ and HCO3-

Question 7

What concentrations are higher in plasma than saliva?

Answer 7

Na+ and Cl-

Question 8

What is the 2 stage process of saliva?

Answer 8

Primary secretion - acini, similar composition to plasma contains amylase, mucous or electrolytes - isotonic
Secondary secretion - striated ducts, change in composition - hypotonic

Question 9

In secondary secretion what happens?

Answer 9

Na+ and Cl- resorbed from duct
K+ and HCO3- secreted
Saliva becomes hypotonic
Ductal epithelium has low permeability to water - hypotonic

Question 10

How does sodium enter and leave the cell?

Answer 10

Sodium enters across the apical membrane via the ENaC Na+ channel and Na-H exchanger.
Na+ exits across the basolateral membrane via the Na-K pump.

Question 11

How does chloride ions enter and leave the cell?

Answer 11

Via the apical Cl-HCO3 exchanger

More Cl- exits via the basolateral than apical Cl- channels

Question 12

What is the evidence for the two stage hypothesis?

Answer 12

Flow rate curves
Acinar/intercalated duct micro puncture
Transport properties of isolated, perfused ducts
Poly-lysine injection poisons ducts and inhibits secondary reabsorption process, saliva becomes like primary fluid

Question 13

How does ionic composition change with flow rates?

Answer 13

At low flow rates, more time available for reabsorption/secretion (hypotonic)
At high flow rates less time available do composition approaches isotonic primary secretion

Question 14

What is unusual about saliva?

Answer 14

Both parasympathetic and sympathetic NS stimulates secretion
Parasympathetic is copious amounts of watery saliva
Sympathetic small amount of saliva, rich in enzymes

Question 15

What are some inputs into the salivary centre?

Answer 15

Taste, smell, chewing and tactile

Question 16

What is ductal transport stimulated by?

Answer 16

Mineralocorticoids (aldosterone) where it is increased In sodium depleted animals sodium concentration falls in saliva