Maintenance of pH Flashcards
kW equation
Kw = [H+][OH-] = 10^-14 M^2
Acid and base ion concentration changes
- Acids [H+] increases and [OH-] decreases•
- Bases:[H+] decreases and [OH-] increases
pH equation
pH = -log10 [H+]
Physiological cell pH range
5-7.6
What acids and bases fully dissociate in water
Strong
What do weak acids/bases do in solution?
Partially dissociate
HA equation
HA < = > H+ + A-
Ka equation
Ka = [H+] [A-] / [HA]
Equation that links pH with conjugate acid/base conc
pH = pK + log ([conjugate base] / [conjugate acid])
Stomach pH
1-3
Plasma pH
7.4
Pancreatic juice pH
8.8
How can pH be regulated
Partitioning and buffering
How is pH regulated through partitioning?
Add a proton pump (Protons can’t cross membranes alone)
How is pH regulated through buffering?
H+ + Buffer ⬄ Buffer-H+
What is carbonic anhydrase?
- Major buffer of the body
- Acts in circulation and in tissues
What is normal blood pH and what pH’s indicates acidosis?
Normal blood pH = 7.4, Acidosis pH = 7.35
What pH can lead to death?
pH around 7
Clinical markers of pH?
- [HCO-3] = 24 mM (pH 7.4) compared to 9.4 mM (pH 7.03)•
- [CO2] = 1.2 mM (pH 7.4) compared to 1.1 mM (pH 7.03)
How is a reduction in [HCO^-3] in the blood significant?
- less HCO^-3 available for buffering
- If more HCO^-3is lost, none is available for additional buffering tasks
What determines the extent of drug dissociation?
pH
What does pK determine with drug administration
the fluid in which to administer drug and the volume administered - influences the concentration of ionised or unionised drug in solution and whether drug will remain in solution or precipitate
Where are weak acid/base drugs secreted into?
Actively secreted into the renal tubule and rapidly excreted
Equation linking pH, pKA and acid dissociation conc
pH = pKa + log ([A-]/[HA])
