Acid and base

Question 1

Define an acid? reaction?

Answer 1

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

Question 2

Define a base? reaction?

Answer 2

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

Question 3

What is the Bronstead-Lawry Theory?

Answer 3

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

H2O + H+ <-> H3O+

Question 4

What can water dissociate into?

Answer 4

H2O <-> OH- + H+

Question 5

In pure water what is [H+]?

Answer 5

pH 7
10^-7

Question 6

Define strong acid?

Answer 6

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

Question 7

Define a weak acid and bases?

Answer 7

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

Question 8

Define base excess?

Answer 8

Quantity of acid required to return plasma pH to normal

Question 9

Define standard base excess?

Answer 9

Quantity of acid required to return extracellular fluid to normal

Question 10

Define buffers?

Answer 10

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

Question 11

How to calculate pH?

Answer 11

pH= -log10[H+]

Question 12

What is normal range of pH?

Answer 12

7.35-7.45

Question 13

Define:
Acidosis
Alkalosis
Acidaemia
Alkalemia

Answer 13

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

Question 14

How are H+ ions produced?

Answer 14

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-

Question 15

Write the equation for H+ production?
Enzyme?

Answer 15

Carbonic anhydrase

Question 16

What speeds up the reaction of CO2 and H2O?

Answer 16

Carbonic anhydrase

Question 17

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

Answer 17

Carbonic anhydrase

Question 18

State the Henderson-Hasselbach equation?

Answer 18

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

Question 19

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

Answer 19

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

Question 19

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

Answer 19

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

Question 20

Define the anion gap?

Answer 20

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

NOT- K+, PO4-, SO4

Question 21

Define cations and anions?

Answer 21

Cations- positive
Anions- negative

Question 22

What is normal anion gap numebr?

Answer 22

3-11 mEq/mol

Question 23

What does a wide anion gap indicate?

Answer 23

Lactic acidosis
Ketoacidosis
Ingestion acid
Renal failure

Question 24

What does a narrow anion gap indicate?

Answer 24

Alkalosis

Question 25

Note diff types of body buffer symptoms?

Answer 25

Bicarbonate
Proteins
Haemoglobin

Question 26

Explain the bicarbonate buffer?

Answer 26

Most imp
Not eff
CO2 removed lungs
Bicarb regenerate kidneys

Question 27

Explain proteins buffer? Examples?

Answer 27

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

Question 28

Explain haemoglobin buffer? Function?

Answer 28

Carry oxygen to tissues
Transport CO2 and buffer H+
Hb binds both CO2 and H+
Powerful buffer

Question 29

Why is deoxygenated Hb important? Process? Lungs? Tissues?

Answer 29

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-