Quick Review Cards for Medical Laboratory Science

TERM EXPLANATION

pH

Acid

Base

Buffer

Bicarbonate

Carbonic acid

Total CO 2

PCO 2

Henderson-Hasselbalch equation

Acid-Base Balance Terminology Clinical Chemistry Review 121

− Log [H+] or log^1

[H+]

Chemical that can yield H+. Proton donor. pH <7

Chemical that can accept H+ or yield OH−. pH >7

Weak acid & its salt or conjugate base. Minimizes changes in pH. Most important 1 for maintaining

blood pH is bicarbonate/carbonic acid. (H++ HCO 3 −¤ H 2 CO 3 ¤ H 2 O + CO 2 ). Others: phosphates,

proteins, hemoglobin

HCO 3 −. Second largest fraction of anions. Proton acceptor or base. Equal to total CO 2 − 1.

Regulated by kidneys

H 2 CO 3. Proton donor or weak acid. Equal to PCO 2 × 0.03. Regulated by lungs

All forms of CO 2. (HCO 3 −+ H 2 CO 3 + dissolved CO 2 )

Partial pressure of CO 2. Directly related to amount of dissolved CO 2.

pH = 6.1 + log

[HCO 3 −]

or 6.1 + log

HCO 3 −

× 0.03

[H 2 CO 3 ] PCO 2

continued...