Biochemistry of Saliva

Question 1

what determines Ph of oral environment?

Answer 1

Protons

Question 2

When do salivary proteins precipitate onto tooth?

Answer 2

When pH = their isoelectric point

Question 3

What drives dissolution of HAP leading to caries?

Answer 3

protons

Question 4

what happens after Carb intake?

Answer 4

pH of plaque fall from neutral to 4.5

Question 5

Why does pH fall after carb intake?

Answer 5

fermentation of carb. by plaque so organic acids

Question 6

What is the critical pH?

Answer 6

below 5.5 where HP dissolves

Question 7

How is Plaque pH restored to neutral?

Answer 7

Salivary buffering

Question 8

What is remineralization?

Answer 8

new mineral precipitated when above critical pH

Question 9

What does Urea do?

Answer 9

increase pH via conversion to ammonia

Question 10

What does high saliva flow rate do?

Answer 10

increase Bicarbonate conc. so inc. buffering capacity so high pH1

Question 11

Where are Bicarbonate ion buffers produced?

Answer 11

striated epithelium of secretory duct & parotid gland

Question 12

What does Enzyme Carbonic Anhydrase do?

Answer 12

forms Carbonic acid (H2C03) from h20 & C02

Question 13

where is carbonic anhydrase present?

Answer 13

made in serous acinar cells in parotid and submandibular glands

Question 14

Where is Bicarbonate ions derived from?

Answer 14

metabolic activities of salivary glands & plasma

Question 15

When does carbonic acid conc. increase?

Answer 15

with increased salivary flow

Question 16

What does Na ion counter?

Answer 16

Bicarbonate ion

Question 17

What does Potassium ion counter?

Answer 17

Phosphate ion

Question 18

When do sodium concentrations increase?

Answer 18

with increased salivary flow

Question 19

What is Potassium concentration in saliva?

Answer 19

CONSTANT

Question 20

How is sodium pumped out of primary salivary fluid?

Answer 20

passes via acini of salivary gland via Na/K pumps

Question 21

What are sources of Magnesium ions in Saliva?

Answer 21

Cell degradation

caries attack

Question 22

What happens to Magnesium con. as flow rate increases?

Answer 22

Mg ions decrease

Question 23

What secretes Ca2+ ions?

Answer 23

Major salivary gland

Question 24

What are calcium ions needed for?

Answer 24

• remineralisation

- prevent mineral dissolution

Question 25

What do calcium form complexes with?

Answer 25

Ca-binding salivary proteins

Question 26

What does increased flow rate do to Calcium conc?

Answer 26

Ca concentration constant

Question 27

What is parotid secretion of Ca compared to submandibular ?

Answer 27

Half the secretion

Question 28

What happens to protein conc. as salivary flow rate increases to more than 1mL/min?

Answer 28

protein increases

Question 29

Why is below 1mL/min, the protein conc. more variable?

Answer 29

proteins can bind to calcium

Question 30

What do Phosphate ions act as?

Answer 30

Buffers

Question 31

Role of Phosphate ions?

Answer 31

inhibit dissolution and bring about repair to mineral

Question 32

What happens to inorganic Phosphate ion as flow rate increases?

Answer 32

DECREASES

Question 33

Why does phosphate decrease with increased salivary flow rate?

Answer 33

Phosphate added to fluid via ducts

Question 34

What does increased flow rate mean for PO43-

Answer 34

less time for phosphate to be added

Question 35

What is HAP/

Answer 35

most stable Ca/ (P04)3- SALT

Question 36

When does HAP precipitate?/

Answer 36

when solubility product is exceeded

Question 37

what does really low conc. of Ca/PO43- mean?

Answer 37

dissolution

Question 38

what does really High conc. of Ca/PO43- mean?

Answer 38

Dental calculus + salivary gland stones

Question 39

What happens to phosphate group when pH falls?

Answer 39

increase protonation so form Calc.Phos salts of greater solubility so demineralization

Question 40

When does caries occur?

Answer 40

when demineralisation rate exceed mineralisation rate

Question 41

Where is Fluoride ion concentration high?

Answer 41

In plaque than saliva

Question 42

What does fluoride replace in HAP ?

Answer 42

OH in crystal lattice structure

Question 43

what does fluoride do to HAP?

Answer 43

Reprecipitates it and More stable and inhibits acid dissolution

Question 44

what picks up fluoride from saliva?

Answer 44

porous enamel and dentine

Question 45

What is fluoride amount in saliva?

Answer 45

small at 0.001-0.005 millimolar

Question 46

What are inorganic components of Saliva?

Answer 46

``` Bicarbonate Na K Mg Ca P043- (orthophosphate) HAP Fluoride ```