Organic and inorganic components of saliva

Question 1

What are the role of salivary mucins?

Answer 1

• Lubrication of hard and soft tissues to avoid harm from mechanical damage
• Bacterial agglutination
• Direction of bacterial colonisation
• Barrier to demineralisation and microbial colonisation
• Antimicrobial and anti fungal activity
• Regulates other salivary proteins
• Protects against dessication (drying out of the mouth)

Question 2

What is the role of statherin and salivary proline rich proteins?

Answer 2

• Inhibition of HAP growth

- Control of mineral deposition and growth

Question 3

What linked sugars do salivary mucins contain?

Answer 3

O- and N- linked sugars

Question 4

What is the common core structure all N-linked oligosaccharides contain?

Answer 4

Three mannose and two N-acetylglucosamine residues

Question 5

What does a mucin monomer contain?

Answer 5

• Oligosaccharide
• Cysteine residue
• Repeat structure

Question 6

What are the two types of salivary mucin?

Answer 6

MG1 and MG2

Question 7

How many different gene products is MG1 a mixture of?

Answer 7

3

Question 8

How many different gene products is MG2 a mixture of?

Answer 8

1

Question 9

Is MG1 an oligomeric structure or monomeric?

Answer 9

Oligomeric

Question 10

Is MG2 an oligomeric or monomeric structure?

Answer 10

Monomeric

Question 11

What does MG1 form complexes with?

Answer 11

Amylase, PRP’s, histatines, statherin and antimicrobial peptides

Question 12

What does MG2 bind to?

Answer 12

Oral pathogens and yeast (candida)

Question 13

Properties of statherin?

Answer 13

High proline content, small, high negative charge, produced by acinar cells, binds to HAP via two possible sites.

Question 14

What are the functions of statherin?

Answer 14

Inhibits crystal growth and precipitation of hydroxyapatite

Question 15

What are properties of proline rich proteins?

Answer 15

Rich in proline, high proportion in total saliva, high negative charge, strongly absorbed to HAP.

Question 16

What are functions of PRP’s?

Answer 16

• Inhibition of HAP growth
• Interact with oral micro-organisms (-NH2 terminal binds COOH terminal interacts with bacterial cell walls)
• Highly selective - exclusion of pathogens

Question 17

What are properties of histatins?

Answer 17

• Rich in histidine
• Basic character due to presence of Arg and Lys
• Bind to HAP
• Small
• Highly conserved

Question 18

Functions of histatins

Answer 18

Potent inhibitor of candida

Buffer?

Question 19

What are the three types of immunoglobulins in saliva and GCF?

Answer 19

IgA, IgM and IgG

Question 20

What are functions of histatins?

Answer 20

• Bacterial agglutination

- Specific Ab-Ag targeting against bacterial adhesins

Question 21

What does amylase do?

Answer 21

Catalyses hydrolytic cleavage of a 1-4 glycosidic linkages. Depends on calcium ions and is chloride activated.

Question 22

Functions of amylase?

Answer 22

CHO digestion (aldehyde)
Interactions with oral micro-organisms
Present in carious lesions
Present in tears

Question 23

What are the properties of lysozymes?

Answer 23

• Originates from striated duct
• Hydrolyses a 1-4 linkages between N-acetylmuramic acid and N-acetylglucosamine in bacterial cell walls
• May co-operate with SlgA (immunoglobulin A)
• Binds to HAP

Question 24

What are the functions of lysozymes?

Answer 24

Bacterial cell wall lysis - antimicrobial

Question 25

What does salivary peroxidases do?

Answer 25

- Catalyses conversion of peroxide (from bacterial metabolism) and thiocyanate into hydrothiocyanite - Important detoxifier - must remove H2O2 to prevent free radical formation, may have a role in perio disease

Question 26

What does lactoferrin do?

Answer 26

Has an antibacterial function, binds Fe 3+ (essential bacterial nutrient)

Question 27

What are cystatins?

Answer 27

Small proteins which are ubiquitous throughout all bodily fluids, binds to HAP

Question 28

What are the functions of cystatins?

Answer 28

Inhibitors of cysteine proteases and protection against acid erosion.

Question 29

What are two examples of pH rise factors?

Answer 29

Urea and slain, these are metabolised to produce ammonia to increase pH and produce putrescine (halitosis)

Question 30

Why are hydrogen ions related to pH?

Answer 30

- Their concentration determines the pH of the oral environment

Question 31

Why does the pH of saliva vary?

Answer 31

According to flow rate (higher flow rate = higher pH

Question 32

Why is pH important in the mouth?

Answer 32

- Maintains ionic product for hydroxyapatite - Isoelectric point for salivary protein precipitation on to tooth surfaces - Optimal pH for salivary enzymes

Question 33

What do higher flow rates of saliva increase?

Answer 33

Salivary buffering

Question 34

What are the MOST important ions in salivary buffering?

Answer 34

Bicarbonate

Question 35

Where are bicarbonate ions produced?

Answer 35

Striated epithelium of the secretory ducts and parotid gland

Question 36

What does bicarbonate ion concentrations increase with?

Answer 36

Increased metabolic activity of salivary glands

Question 37

What is the counter ion for bicarbonate?

Answer 37

Sodium

Question 38

What is the counter ion for phosphate?

Answer 38

Phosphate

Question 39

Do sodium ions increase when flow rate increases?

Answer 39

Yes

Question 40

Do potassium ions increase when flow rate increases?

Answer 40

Stays the same

Question 41

What are the possible origins of magnesium ions?

Answer 41

Cellular degradation | Early carious attack

Question 42

Do magnesium ions increase or decrease with an increased flow rate?

Answer 42

Decrease

Question 43

What do calcium ions do in the mouth?

Answer 43

- Form complexes with calcium binding salivary proteins | - Important role in maintenance of ionic product for hydroxyapatite

Question 44

Do calcium ions increase with increased flow rate?

Answer 44

Stay the same

Question 45

What do phosphate ions do?

Answer 45

- Act as a buffer, especially in unstimulated saliva | - Important in maintenance of ionic product for hydroxyapatite

Question 46

Do phosphate ions increase with increased salivary flow?

Answer 46

Decrease

Question 47

What is the formula of hydroxyapatite?

Answer 47

Ca10(Po4)6(OH)2