Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

DS1102 > Week 1 - Buffers, Drugs and Hydroxyapatite + F- Intro > Flashcards

Week 1 - Buffers, Drugs and Hydroxyapatite + F- Intro Flashcards

1
Q

What are buffers

A

Buffers are a solution which resists pH changes when small amounts of acid or base are added. They are known as a “pH shock absorber”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are buffers made up of

A

Buffer = weak acid + conjugate base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the buffer capacity

A

measure of the ability of the buffer to resists pH change. the more concentrated the components of the buffer the greater the buffer capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the buffer ratio

A

buffer ratio = [base]/[acid]

The best buffering is achieved at a ratio of 1

The range of 0.1 - 10 is effective

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the Henderson-hasselbach equation

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the main types of buffer systems in the oral cavity

A
  • bicarbonate HCO3-
  • phosphate H2PO4-
  • protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the carbonic acid/ bicarbonate buffer

A

Buffer between carbonic acid and bicarbonate anion

This buffer helps maintain the blood plasma at pH 7.4 (7.35 - 7.45).
- Primary buffer system
- Primary buffer in stimulated saliva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the equation for the bicarbonate buffer

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the pKa of the carbonic acid/ bicarbonate buffer

A

6.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What pH range does the bicarbonate buffer operate in

A

5.1 - 8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the phosphate buffer (dihydrogen phosphate buffer)

A
  • The buffer system involves H2PO4- - - - dihydrogen phosphate and its conjugate base hydrogen phosphate.
  • This system is the secondary buffer in saliva
  • Buffer in unstimulated saliva
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the equation for the phosphate buffer - dihydrogen phosphate buffer

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the pKa of the phosphate buffer

A

7.2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What pH range does the phosphate buffer operate in

A

5.1 -8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are protein buffers

A

Protein buffers are solutions that helps maintain the pH at a stable level during biochemical processes involving proteins.

Proteins buffer cells and blood plasma through carboxylic acid and amine buffers. The side chains of some amino acids are ionizable and hence can act as weak acids and bases, hence forming buffer solution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the primary buffer in unstimulated saliva

A

phosphate buffer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the primary buffer system in stimulated saliva

A

carbonic/bicarbonate buffer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is an equation for a protein buffer using Asp

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What pH range does protein buffers operate in

A

3.4 - 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What must organic acids contain at least one of

A
  • carboxylic acid group (CO2H)
  • Sulphonic acid group (SO3H)
  • phosphoric acid group (PO2H2)
  • Phenolic OH group (Ar-OH)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the composition of enamel

A
  • 96% mineral by weight
  • 3% water
  • 1% proteins (amelogenin and enamelin)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is the major mineral in enamel

A

Hydroxyapatite (HAP) Ca10(PO4)6(OH)2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is the simplified formula for hydroxyapatite HAP

A

Ca10(PO4)6(OH)2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the demineralization and remineralization equation of enamel

A
25
Q

What is Ksp

A

solubility product

26
Q

if Qsp > Ksp then

A

precipitate will precipitate

27
Q

if Qsp = Ksp then

A

solution is at saturation

28
Q

if Qsp < Ksp then

A

no precipitate will form

29
Q

What is degree of saturation

A

Degree of saturation (DS) is the ration of the ionic product (Q) of a substance in the solution to its ionic product at saturation (Ksp)

30
Q

How does demineralization occur

A

The tooth will dissolve when the pH of the fluid phase in contact with it is less than the critical pH 4.5-5.5, because at this point we there is a net loss of minerals - removes PO4^-3 and OH- from HAP (Apatite mineral dissolves)

31
Q

Can demineralization occur if the fluid adjacent to the tooth surface is supersaturated with calcium, phosphate and hydroxide ions

A

No

32
Q

At what DS does demineralization occur

A

If DS < 1: solution undersaturated with mineral

33
Q

At what DS does remineralization occur

A

DS > 1: solution supersaturated with mineral

34
Q

What pH does caries form

A

4.5 - 5.5

35
Q

WHat pH does dental erosion occur

A

3 - 4.5

36
Q

How does Fluoroapatite (FAP) form

A

Fluoroapatite (FAP) is formed when we’ve substituted the OH- with fluoride. FAP is more stable when under low pH in comparison to HAP. Hence has a lower critical pH of 4.5

37
Q

What are the effects of Fluoride

A
  1. Inhibits demineralization
  2. Enhances Mineralization
  3. Inhibiting enolase
38
Q

How does fluoride inhibit demineralization

A

Inhibits demineralization - as defects are produced in enamel (removal of OH) F- binds to the Ca+ to fill in, forming a more stable structure which is resistant to acid attacks (improves the crystallinity which lowers dissolution rate)

39
Q

How does fluoride enhance mineralization

A

With sufficient F- and Ca+2 around fluoride will form a fluorapatite like material on the crystal surface under CaF2 like globules.
- partially demineralized enamel crystals found in caries act as nucleator where F- bind to. The F- then attracts Ca and P to rebuild the apatite like material on the surface. ‘Forming a FAP like veneer

40
Q

How does fluoride inhibit enolase

A

Fluoride competitively inhibits enolase which is the enzyme used to catalyse step 9 of glycolysis. Hence the lactic acid fermentation process cannot occur and lactic acid from oral bacterial will not be produced - reduce growth of mutant streptococcus.

41
Q

What is the recommended prescription of fluoride

A
  • low level
  • frequent exposure
  • life long use
42
Q

What is the critical pH of FAP

A

4.5

43
Q

What does critical pH mean

A

the pH at which a solution is just saturated WRT a particular mineral

44
Q

What occurs if the solution pH > critical pH and supersaturated

A

mineral precputates

45
Q

What occurs if the solution < critical pH and undersaturated

A

mineral dissolves

46
Q

What are examples of corrosive substances

A

HF - FLuoric acid
H3PO4 - Phosphoric acid

Corrosive means that it causes irreversible chemical damage/destruction of other substances, particularl biological and metals, damage occurs at the site of contact

47
Q

What is the normal pH range of saliva

A

6.2 - 7.6 (7.4)

48
Q

How do you name the conjugate base of an acid

A

Add -ate to the end of the name
e.g. acid = aspartic acid
conjugate base = aspartate (-1)

49
Q

What is the resting pH in the mouth

A

> 6.3

50
Q

Sports drinks contain electrolytes why do you imagine regular consumption of these drinks in athletes is bad for their teeth

A

Carbohydrate and phosphoric acid is used as a preservative - this causes the drink to be acidic and can cause caries formation

51
Q

what range does a buffer best operate in

A
52
Q

Which saliva buffer system are responsible for buffering during dental erosion

A

protein

53
Q

Why is the critical pH lower for FAP than HAP

A

the fluoride has a higher electrostatic attraction to the surrounding calcium creating a more stable structure which is less likely to loss minerals

54
Q

What is the formula for fluorhydroxyapatite

A

Ca10(PO4)6F2

55
Q

Define critical pH

A

pH where there is a net mineral loss of a substance

56
Q

What is the importance of acid base equilibria and drugs

A

acid and base equilibria can alter the charge state of a a drug which can in turn impact where they are able to travel in the body.
e.g.
Only non polar (non ionised) substances will cross a cell membrane
pronated and acidic froms of a drug is very soluble and can be transported within the blood stream

57
Q

What is the weak acid used in dentistry for etching surfaces

A

phosphoric acid

58
Q

At a pH of 5.7 what is the primary buffer acting in the oral cavity

A

phosphate buffer

DS1102 (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions