Acid - Base Balance

HA <===> H⁺ + A^-

K_eq = [H⁺] + [A^-]

[HA]

Henderson-Hasselbalch
Equation

[H+] = K_eq x [HA]

[A-]

-log [H+] = -log K_eq + log [A-]

[HA]

pH = pK_a + log [A-]

[HA]

pK_a

when pH = pK, acid is 50% dissociated

when pH = pK, 50% of buffer is in each form giving maximum buffering capacity

match pK of potential buffers to desired pH

Metabolism

Constant source of H+ and thus reduces plasma pH

Proteins --> H₂SO₄ , HCl, H₃PO₄

Fats --> ketone bodies such as acetone & b hydroxybutyric acid

Oxidation ---> H⁺ from CO₂

Plasma Buffers

H₂CO₃

H₃PO₄ and organic phosphates

Proteins at ionized ‘R’ groups

Plasma Bicarbonate

[HCO₃^-]_plasma = 23 mEq/L

Changes indicate renal or respiratory problems

CO₂ + H₂O <----> HCO₃^- + H⁺

OPEN BUFFER SYSTEM!

Some Clarifying Images?

Cells of PCT & DCT