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Chemistry Flashcards

1
Q

What are acids?

A

Molecules/ions that give up protons in solution

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2
Q

What is the reaction for acids in solution?

A

HX –> H+ + X-

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3
Q

What is the ionisation reaction for water?

A

H2O <–> H+ + OH-

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4
Q

What is the ionisation reaction for acetic acid?

A

CH3COOH <–> H+ + CH3COO-

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5
Q

What are bases?

A

A molecule/ion that acquire protons in solution

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6
Q

What is the reaction for bases in solution?

A

X- + H+ –> HX

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7
Q

What is the ionisation reaction for the hydroxyl ion in bases?

A

OH- + H+ –> H2O

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8
Q

What is the ionisation reaction for the acetate ion in bases?

A

CH3COO- + H+ <–> CH3COOH

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9
Q

What is the ionisation reaction for ammonia in bases?

A

NH3+ + H+ <–> NH4+

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10
Q

What is the ionisation reaction for amines in bases?

A

R-NH2 + H2 <–> R-NH3+

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11
Q

What is the conjugate acid and base in:m
HX <—> H+ + X-

A

Conjugate acid= HX
Conjugate base= X-

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12
Q

What is the equation for Ka?

A

([H+][X-])/[HX]

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13
Q

What is the effect of a larger pKa?

A

The larger the pKa, the smaller the extent of dissociation

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14
Q

What is the dissociation constant?

A

A quantitive measure of the strength of acid in solution

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15
Q

What is Ka?

A

The acid dissociation constant

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16
Q

What is the Ka of water?

A

Ka= 1.8 x 10 ^-16

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17
Q

What is the equation for pH?

A

pH= log10[H+]

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18
Q

What is the dissociation reaction for carbonic acid?

A

H2CO3 <—> H+ + HCO-

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19
Q

What is the pKa of carbonic acid?

A

6.37

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20
Q

When is carbonic acid formed in humans?

A

When CO2 dissolves in blood tissue fluids

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21
Q

What is the function of carbonic acid in blood at a physiological pH?

A

Buffer

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22
Q

What is the dissociation reaction of lactic acid?

A

CH3CH(OH)COOH <—> H+ + CH3CH(OH)COO-

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23
Q

When is lactic acid formed?

A

By human cells from glucose during anaerobic respiration, especially in muscles during rapid movement

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24
Q

What is the pKa of lactic acid?

A

3.86

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25
Q

What does lactic acid cause?

A

Cramp

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26
Q

How is lactic acid converted into glucose?

A

Gluconeogenesis in the liver (Cori cycle)

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27
Q

What is the dissociation reaction for hydrochloric acid?

A

HCl <—> H+ + Cl-

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28
Q

What is the function of hydrochloric acid in the body?

A

Secreted into the stomach for digestion

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29
Q

What is the pKa of hydrochloric acid?

A

<1

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30
Q

What are examples of acids produced by oral bacteria?

A

Lactic acid
Formic acid
Acetic acid
Propionic acid
Butyric acid

31
Q

What is the fomula and pKa of formic acid?

A

HCOOH
pKa= 3.75

32
Q

What is the fomula and pKa of acetic acid?

A

CH3COOH
pKa= 4.73

33
Q

What is the fomula and pKa of propionic acid?

A

CH3CH2COOH
pKa= 4.87

34
Q

What is the fomula and pKa of butyric acid?

A

CH3CH2CH2COOH
pKa= 4.82

35
Q

What is the equation for the dissociation of calcium phosphate (hydroxyapatite) by acids?

A

Ca10(PO4)6(OH)2 + 8H+ <—> 10Ca2+ + 6HPO4 2- +2H2O

Ca10(PO4)6(OH)2 + 14H+ <—> 10Ca2+ + 6H2PO4- + 2H2O

36
Q

Discuss the effect of shifts to left/right in the dissociation of calcium phosphate?

A

An increase in [H+] causes there equilibrium to shift to the right, increasing the solubilisation of calcium phosphate

An increase in calcium or phosphate concentration causes the equilibrium to shift to the left inhibiting solubilisation and promoting remineralisation

37
Q

What is the role of saliva in regard to calcium phosphate dissocation?

A

Saliva contains calcium and phosphate to aid remineralisation

38
Q

What is the pH of acidic drinks?

A

2-4

39
Q

What do organic acids act as?

A

Chelating agents: bind strongly to divalent and trivalent cations
Bind calcium ions which are then no longer available to counteract calcium solubilisation and contributes to tooth erosion

40
Q

What is a buffer?

A

Consist of similar concentration of the conjugate acid or conjugate base
Made by neutralising the an acid with OH- or mixing together a solution of acid and one of its salt at an appropriate Ka

41
Q

What is the % dissociation at maximum buffering capacity?

A

50%

42
Q

What is the Henderson-Hasselbalch equation?

A

pH= pKa + log10 (salt/acid)

43
Q

Where does a buffer have effective buffering capacity?

A

Within +/- pH unit of its pKa

44
Q

What is the main buffer in saliva?

A

HCO3- (bicarbonate)

45
Q

What other factors contribute to the buffering capacity of saliva?

A

Phosphate
Protein

46
Q

Where does the bicarbonate in saliva come from?

A

Blood
Action of carbonic anhydrous (enzyme that forms carbonic acid)- carbonic acid dissociates into hydrogen and bicarbonate

47
Q

What pH is the major buffering capacity of saliva?

A

6.7

48
Q

What are the three equilibria and their pKa for phosphate as a buffer?

A

H3PO4 <—> H+ + H2PO4 (pKa=2.16)
H2PO4- <—> H+ +HPO4 2- (pKa=7.21)
HPO4 2- <—> H+ +PO4 3- (pKA=12.32)

49
Q

What are examples of salivary proteins that have carboxylic acids in their side chain?

A

Aspartic acid
Glutamic acids

50
Q

What is an example of a salivary protein that has an imidazole side chain?

A

Histidine

51
Q

What is the pH of blood?

A

7.4

52
Q

What are the buffers in blood?

A

Bicarbonate and protein buffers

53
Q

What is membrane potential?

A

Potential difference across the membrane of all cells

54
Q

What is the difference in membrane potential between ICF and ECF?

A

ICF is more negative than ECF
Equal number of positive and negative charges but the ion distribution is more polarised;

55
Q

What is the ECF and ICF composition of sodium?

A

ECF: 145 mM
ICF: 15 mM

56
Q

What is the ECF and ICF composition of potassium?

A

ECF: 4 mM
ICF: 150 mM

57
Q

What is the ECF and ICF composition of chlorine?

A

ECF: 110 mM
ICF: 10 mM

58
Q

What is the permeability of the cell membrane at resting potential in Na+ and K+?

A

Impermeable to Na+
Permeable to K+

59
Q

What molecule is responsible for resting potential?

A

Potassium- diffuses out of the cell leaving excess negative inside the cell
Sodium-Potassium Pump

60
Q

Discuss the development of an action potential:

A

-70kV
Stimuli occurs causing initial depolarisation
-55kV: Na+ channels open causing Na+ influx
+35kV: Na+ channels close, K+ channels open causing K+ efflux
-70kV: refractory period, inexcitability, h gate closed

61
Q

Discuss the gating of voltage gated sodium channels-

A

Resting membrane potential- (closed)
m gate CLOSED
h gate OPEN

Threshold potential- (open)
m gate OPEN
h gate OPEN

Repolarisation- (closed)
m gate OPEN
h gate CLOSED

62
Q

Discuss the gating of voltage gated potassium channels-

A

Closed or open

63
Q

Discuss action potential propagation-

A

Action potential travels along the axon as a wave of depolarisation
Speed of propagation increases with axon diameter and myelination

64
Q

What cells lay down the myelin sheath?

A

Glial cells

65
Q

What is the myelin shealth interupted by?

A

Nodes of Ranvier

66
Q

How does the myelin sheath propagate the action potential?

A

Nerve action potential jumps to nodes of ranvier leading to faster propagation

67
Q

What kind of axons do peripheral nerves contain?

A

Many axons varying in:
Size and Function

68
Q

What are the three types of cutaneous nerves?

A

A-beta
A-alpha
C fibres

69
Q

Are A-beta nerves myelinated or unmyelinated?

A

Myelinated

70
Q

What type of receptors are A-beta nerves?

A

Mechanoreceptors

71
Q

Are A-alpha nerves myelinated or unmyelinated?

A

Myelinated

72
Q

Are C fibre nerves myelinated or unmyelinated?

A

Unmyelinated

73
Q

What type of receptors are A-alpha nerves?

A

Mechanoreceptors
Thermoreceptors (cold)
Nociceptors
Chemoreceptors (taste)

74
Q

What type of receptors are C fibre nerves?

A

Mechanoreceptprs
Thermoreceptors (hot and cold)
Nociceptors

Finals (20 decks)

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