Acids/Bases

Question 1

• Law of mass action?
• Pka def? lower pka means? eq?
• ph measures? eq? Increasing ph by 0.3?
• HH used for what? eq? At 50% dissoc?
• HH for bicarbonate buffer system?
• Open or closed system? Modulated by? (2)

Answer 1

• keq = [prod]/[react]
• propensity to donate or accept protons; higher acidity; pka = -log ka
• Acidity; ph= -log [H+]; doubles H+ conc.
• weak acids and bases; ph = pka + log [A-]/[HA]; ph=pka
• ph = 6.1 = log [HCO3-] mM / 0.03 P CO2 mmHg
  (dec with met. acid) (incr. w resp acidosis)
• open; CO2 at lungs and H+/HCO3- in kidney

Question 2

• Normal blood: Arterial pH? Venous pH? Cytosol pH? Gastric juice pH? [HCO3-]? P CO2?
• When ratio of HCO3- to CO2 is 20; ph=?
• Maximum buffering capacity? (2)
• Pepsin vs. Trypsin?

Answer 2

• 7.34-7.44; 7.28-7.42; 6.9; 1.4-3.0; 24 mM; 40 mmHg
• 7.4
• [A-]/[HA] = 0.1 to 10 or +/- 1 pH
• Pepsin from stomach = active at pH of 2
• Trypsin from duodenum = active at pH of 6