L4 - pH and buffering Flashcards
what is the average blood pH
7.35 - 7.45
what is the living blood pH range
7.0 - 7.8
sources of acids?
diet (vinegar / lemon / chilli)
protein breakdown
incomplete oxidation of fats/carbs
CO2 transport in blood
what does a buffer consist of
weak acid and conj base
what regulates pH
lungs
kidneys
chemical buffers
what does a buffer do
resists changes in pH by
releasing H+ when pH high
binding H+ when pH drops
what is the M of pure water
55.6 Moles per litre
what is pKa
the pH at which the weak acid is half dissociated
what does lower pKa mean
stronger weak acid
what does higher pKa mean
weaker weak acid
why is pKa the pH at which an acid will buffer best
because there is plenty of acid and conj base to accept / donate H+
list physiologically important buffers
- H2CO3 —> HCO3-
- H2PO4 —> HPO4 2-
- protein —> protein-
- protein —> protein+
- NH4+
what happens when [HCO3-] low
metabolic acidosis
what happens when [H2CO3] high
respiratory acidosis
give an example of an amino acid that is a good physiological buffer and its pKa
histidine
pKa 6