Acid and base Flashcards

1
Q

Define an acid? reaction?

A

Proton/H+ donor
HA (acid) <-> H+ + A- (conjugate base)

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2
Q

Define a base? reaction?

A

Proton/H+ acceptor
B (base) + H+ <-> BH+ (conjugate acid)

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3
Q

What is the Bronstead-Lawry Theory?

A

Protons can’t exist alone in solution as possess high charge density so bind to water molecule

H2O + H+ <-> H3O+

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4
Q

What can water dissociate into?

A

H2O <-> OH- + H+

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5
Q

In pure water what is [H+]?

A

pH 7
10^-7

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6
Q

Define strong acid?

A

Compound ionizes completely in solution to form hydrogen ions and a base

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7
Q

Define a weak acid and bases?

A

Compounds that only partially ionize in solution
H2CO3 <-> H+ + HCO3-
Resulting anion (bicarbonate) referred to as conjugate base of carbonic acid

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8
Q

Define base excess?

A

Quantity of acid required to return plasma pH to normal

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9
Q

Define standard base excess?

A

Quantity of acid required to return extracellular fluid to normal

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10
Q

Define buffers?

A

Weak acids/bases with conjugate base or acid Solution resists changes in pH when small quantities of strong acids or base are added.

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11
Q

How to calculate pH?

A

pH= -log10[H+]

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12
Q

What is normal range of pH?

A

7.35-7.45

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13
Q

Define:
Acidosis
Alkalosis
Acidaemia
Alkalemia

A

Acidosis: blood more acidic than normal
Alkalosis: blood more alkaline than normal
Acidaemia: low blood pH
Alkalaemia: high blood pH

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14
Q

How are H+ ions produced?

A

Generated by metabolism
Small quant- oxidation aa
- anaerobic met glucose to
lactic and pyretic acid
Main- CO2 release from oxidative (aer) met
- CO2 react water form carbonic acid
(H2CO3)
- H2CO3 dissociates int hydrogen and HCO3-

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15
Q

Write the equation for H+ production?
Enzyme?

A

Carbonic anhydrase

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16
Q

What speeds up the reaction of CO2 and H2O?

A

Carbonic anhydrase

17
Q

What is the most important buffering system and what catalyses it?

A

Carbonic anhydrase

18
Q

State the Henderson-Hasselbach equation?

A

pH = pK + log10 ([Base]/[Acid])

19
Q

What is the value of CO2 constant?
What is equation for carbonic acid/bicarbonate?

A

0.03
pH = 6.1 + log10 (25mM / (0.03 x 40 mmHg))

19
Q

What is the value of CO2 constant?
What is equation for carbonic acid/bicarbonate?

A

0.03
pH = 6.1 + log10 (25mM / (0.03 x 40 mmHg))

20
Q

Define the anion gap?

A

Difference in serum concentration of cations (positive) and anions (negative)
e.g Cl-, HCO3-, Na+, K+

NOT- K+, PO4-, SO4

21
Q

Define cations and anions?

A

Cations- positive
Anions- negative

22
Q

What is normal anion gap numebr?

A

3-11 mEq/mol

23
Q

What does a wide anion gap indicate?

A

Lactic acidosis
Ketoacidosis
Ingestion acid
Renal failure

24
What does a narrow anion gap indicate?
Alkalosis
25
Note diff types of body buffer symptoms?
Bicarbonate Proteins Haemoglobin
26
Explain the bicarbonate buffer?
Most imp Not eff CO2 removed lungs Bicarb regenerate kidneys
27
Explain proteins buffer? Examples?
Albumin Contain weak acidic and basic groups Plasma and proteins imp buffer E.g. Intracellular proteins limit pH change in cells Protein matrix bone buffer H+ ion in case of chronic acidosis
28
Explain haemoglobin buffer? Function?
Carry oxygen to tissues Transport CO2 and buffer H+ Hb binds both CO2 and H+ Powerful buffer
29
Why is deoxygenated Hb important? Process? Lungs? Tissues?
Strongest affinity CO2 and H+ Buffering effect strongest in tissues - Little CO2 produced in red cells means CO2 produced by tissues passes into cell, down concentration gradient. CO2 combines directly reversibly with terminal amine groups on haemoglobin molecule to form carbominohaemoglobin. In lungs- CO2 released - passes down concentration gradient to alveoli – buffering of CO2 In tissues- dissolved CO2 passes into RBCs, combine carbonic acid - catalysed by carbonic anhydrase - carbonic acid dissociates into bicarbonate and H+ ions - H+ ions bind to reduced haemoglobin to form HHb - HCO3- pass back into plasma in exchange for Cl-