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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
What does lactic acid cause?
Cramp
26
How is lactic acid converted into glucose?
Gluconeogenesis in the liver (Cori cycle)
27
What is the dissociation reaction for hydrochloric acid?
HCl <---> H+ + Cl-
28
What is the function of hydrochloric acid in the body?
Secreted into the stomach for digestion
29
What is the pKa of hydrochloric acid?
<1
30
What are examples of acids produced by oral bacteria?
Lactic acid Formic acid Acetic acid Propionic acid Butyric acid
31
What is the fomula and pKa of formic acid?
HCOOH pKa= 3.75
32
What is the fomula and pKa of acetic acid?
CH3COOH pKa= 4.73
33
What is the fomula and pKa of propionic acid?
CH3CH2COOH pKa= 4.87
34
What is the fomula and pKa of butyric acid?
CH3CH2CH2COOH pKa= 4.82
35
What is the equation for the dissociation of calcium phosphate (hydroxyapatite) by acids?
Ca10(PO4)6(OH)2 + 8H+ <---> 10Ca2+ + 6HPO4 2- +2H2O Ca10(PO4)6(OH)2 + 14H+ <---> 10Ca2+ + 6H2PO4- + 2H2O
36
Discuss the effect of shifts to left/right in the dissociation of calcium phosphate?
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
What is the role of saliva in regard to calcium phosphate dissocation?
Saliva contains calcium and phosphate to aid remineralisation
38
What is the pH of acidic drinks?
2-4
39
What do organic acids act as?
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
What is a buffer?
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
What is the % dissociation at maximum buffering capacity?
50%
42
What is the Henderson-Hasselbalch equation?
pH= pKa + log10 (salt/acid)
43
Where does a buffer have effective buffering capacity?
Within +/- pH unit of its pKa
44
What is the main buffer in saliva?
HCO3- (bicarbonate)
45
What other factors contribute to the buffering capacity of saliva?
Phosphate Protein
46
Where does the bicarbonate in saliva come from?
Blood Action of carbonic anhydrous (enzyme that forms carbonic acid)- carbonic acid dissociates into hydrogen and bicarbonate
47
What pH is the major buffering capacity of saliva?
6.7
48
What are the three equilibria and their pKa for phosphate as a buffer?
H3PO4 <---> H+ + H2PO4 (pKa=2.16) H2PO4- <---> H+ +HPO4 2- (pKa=7.21) HPO4 2- <---> H+ +PO4 3- (pKA=12.32)
49
What are examples of salivary proteins that have carboxylic acids in their side chain?
Aspartic acid Glutamic acids
50
What is an example of a salivary protein that has an imidazole side chain?
Histidine
51
What is the pH of blood?
7.4
52
What are the buffers in blood?
Bicarbonate and protein buffers
53
What is membrane potential?
Potential difference across the membrane of all cells
54
What is the difference in membrane potential between ICF and ECF?
ICF is more negative than ECF Equal number of positive and negative charges but the ion distribution is more polarised;
55
What is the ECF and ICF composition of sodium?
ECF: 145 mM ICF: 15 mM
56
What is the ECF and ICF composition of potassium?
ECF: 4 mM ICF: 150 mM
57
What is the ECF and ICF composition of chlorine?
ECF: 110 mM ICF: 10 mM
58
What is the permeability of the cell membrane at resting potential in Na+ and K+?
Impermeable to Na+ Permeable to K+
59
What molecule is responsible for resting potential?
Potassium- diffuses out of the cell leaving excess negative inside the cell Sodium-Potassium Pump
60
Discuss the development of an action potential:
-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
Discuss the gating of voltage gated sodium channels-
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
Discuss the gating of voltage gated potassium channels-
Closed or open
63
Discuss action potential propagation-
Action potential travels along the axon as a wave of depolarisation Speed of propagation increases with axon diameter and myelination
64
What cells lay down the myelin sheath?
Glial cells
65
What is the myelin shealth interupted by?
Nodes of Ranvier
66
How does the myelin sheath propagate the action potential?
Nerve action potential jumps to nodes of ranvier leading to faster propagation
67
What kind of axons do peripheral nerves contain?
Many axons varying in: Size and Function
68
What are the three types of cutaneous nerves?
A-beta A-alpha C fibres
69
Are A-beta nerves myelinated or unmyelinated?
Myelinated
70
What type of receptors are A-beta nerves?
Mechanoreceptors
71
Are A-alpha nerves myelinated or unmyelinated?
Myelinated
72
Are C fibre nerves myelinated or unmyelinated?
Unmyelinated
73
What type of receptors are A-alpha nerves?
Mechanoreceptors Thermoreceptors (cold) Nociceptors Chemoreceptors (taste)
74
What type of receptors are C fibre nerves?
Mechanoreceptprs Thermoreceptors (hot and cold) Nociceptors

Finals (20 decks)

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