pH and Buffers - Exam Questions Flashcards
What is pH a measure of the concentration of?
Plasma free H+ ions
What is the normal range for pH in the human blood?
7.35-7.45
Term for low blood pH
Acidaemia
How are acids generated in the body?
Transport of carbon dioxide in the blood
What are the main organs which regulate acid-base balance?
Lungs and kidneys
Function of buffers
Minimise pH change in solutions
What is pKa?
The pH at which an acid is half dissociated
A weak acid
a. is also a strong base
b. may behave as an acid or base, depending on the pH
c. becomes a strong acid at high concentration
d. has a low pKa
e. has a low pH
b. A weak acid may behave as an acid of base, depending on the pH
What is the Henderson-Hasselbalch equation?
pH=pKa+log(A-/HA)
A buffer is
a. any weak base, without an acid
b. a weak acid and a strong base
c. a weak acid and its conjugate base
d. a strong acid and a weak base
e. either a weak acid or a weak base
c. A buffer is a weak acid and it’s conjugate base
In a solution with a pH equal to the pKa of a buffer, any applied change in pH
a. is not possible
b. occurs at a faster rate
c. is quickly reversed
d. is slowly reversed
e. occurs at a slower rate
e. In solution wher pH=pKa of buffer, any change in pH occurs at a slower rate
What is the most important buffer in blood?
Carbonic acid
Which amino acid can act as a buffer?
Histidine
Why can haemoglobin buffer well?
Many of its amino acid side-chains (high amount of histidine residues in haemoglobin) have a pKa close to blood pH.
