Saliva Composition And Secretion

Question 1

Parasympathetic stimulation leads to

Answer 1

copious flow of watery saliva and vasodilation

Question 2

Sympathetic stimulation leads to

Answer 2

a smaller amount of saliva secretion, rich in enzymes

Question 3

Stimulants that trigger salivary stimulation include:

Answer 3

− Food in the mouth – reflex
− The thought of food – cephalic (e.g. Pavlov’s dog)
− Sickness/nausea – e.g. water brash as a symptom of gastroesophageal reflux

Question 4

The submandibular glands secrete

Answer 4

seromucous saliva – 70% of total secretion

Question 5

The parotid glands secrete

Answer 5

secrete serous saliva – 25% of total secretion

Question 6

The sublingual glands secrete

Answer 6

mucous saliva – 5% of total secretion

Question 7

Lysozyme and peroxidases

Answer 7

oral hygiene – antibacterial and protection of soft tissue

Question 8

Calcium and bicarbonate ions →

Answer 8

Mineralisation of HAP and neutralisation of acids

Question 9

Mucins

Answer 9

lubrication–protection from desiccation/or bacterial colonisation

Question 10

Amylase(ptyalin)andlipase

Answer 10

digestion–carbohydratesandlipids

Question 11

The theory is that saliva is secreted in a two-stage process:
1. Primary secretion –
2. Secondary secretion –

Answer 11

1. acini secrete saliva (sometimes contains mucous) into the striated ducts
2. the composition of saliva is altered by ductal modification

Question 12

Ductal modification –

Answer 12

cells of the acinus have transporters on both their membranes

Question 13

Sodium

Answer 13

o Enters through ENaC (epithelial sodium channel) in apical membrane
o Enters through sodium-hydrogen exchangers in apical and basolateral membranes
o Exits through sodium-potassium pump in basolateral membrane

Question 14

Potassium

Answer 14

o Enters through sodium-potassium pump in basolateral membrane
o Exits through potassium-hydrogen exchanger in apical membrane

Question 15

Chloride

Answer 15

o Enters through chloride-bicarbonate exchanger in apical membrane
o Exits through CFTR channels in apical and basolateral membranes

Question 16

Bicarbonate

Answer 16

o Exits through chloride-bicarbonate exchanger in apical membrane

Question 17

Overall:
➢ … and … are reabsorbed from the duct into cells of the …
– (They are … )

➢ … and … are secreted into the … (to a lesser extent)
– (they are …)

➢ Saliva becomes …

Answer 17

Sodium
Chloride
Acinus
Removed

Potassium
Bicarbonate
Lumen
Added

Hypotonic

Question 18

Evidence for two-stage hypothesis:

Answer 18

▪ Flow rate curves
▪ Acinar/intercalated duct micropuncture
▪ Transport properties of isolated, perfused ducts
▪ Poly-lysine injection – inhibits secondary reabsorption, saliva becomes like primary fluid

Question 19

As salivary … … increases, so does … of saliva:

Answer 19

Flow rate
Composition

Question 20

There is more time available for ductal modification at … flow rates – … saliva
➢ … potassium, … sodium, bicarbonate and chloride

There is less time available for ductal modification at … flow rate – … saliva
➢ … potassium, … sodium, bicarbonate and chloride

Answer 20

Low
Hypotonic
More
Less

High
Primary
Less
More

Question 21

Taste stimulation has a large effect on salivary composition:
• Acidic tastes cause … salivary flow
• This is due to the fact that ..

so more saliva is secreted in order to … – bicarbonate concentration …

Answer 21

Maximal

hydrogen ions disrupt the buffer system,

Neutralise the low ph

Increases