Buffer System

Buffer systems * prevent major changes in pH of body fluids by removing or releasing H+ * act quickly to prevent excessive changes in H+ concentration.
Body’s major extracellular buffer system is “bicarbonate-carbonic acid buffer system”. There are 20 parts of (HCO3) to one part of (H2CO3). ---- [20:1]. When the ratio is no longer maintained, it will result to acid-base imbalance.
Carbon dioxide is a potential acid; when dissolved in water, it becomes carbonic acid.

Lungs under the control of medulla control the CO2, and thus the carbonic content of ECF. They do so by adjusting ventilation in response to the amount of CO2 in the blood. A rise in PaCO2 is powerful response to stimulant.
Respiratory Compensation * is a mechanism by which plasma pH can be altered by varying the respiratory rate. * breathing is altered to modify the amount of CO2 in circulation.

Kidneys regulate bicarbonate level in the ECF; they can regenerate bicarbonate ions as well as reabsorb them from renal tubules. Renal compensation for imbalances is relatively slow (a matter of hours or days). * The kidneys have two important roles in the maintaining of the acid-base balance:

1. to reabsorb bicarbonate
2. to excrete hydrogen ions into urine.

Bicarbonate Buffer System * 2 components (H2CO3) carbonic acid, a weak acid and (NaHCO3) a weak base. * 1. If a potential pH change is created by a strong acid, the ff. takes place:
HCL + NaHCO3 NaCl + H2CO3 (strong acid) (weak acid) 2. If a potential pH changes is created by strong base, the ff. reaction takes place:
NaOH + H2CO3 H2O + NaHCO3
(strong base) (weak base)