Page 275 - Saunders Comprehensive Review For NCLEX-RN

4. Phosphate buffer system
a. System is present in cells and body
fluids and is especially active in the
kidneys.
b. System acts like bicarbonate and
neutralizes excess hydrogen ions.
C. Lungs
1. The lungs are the second defense of the body; they
interact with the buffer system to maintain acid-base
balance.
2. During acidosis, the pH decreases and the

respiratory rate and depth increase in an attempt to
exhale acids. The carbonic acid created by the
neutralizing action of bicarbonate can be carried to
the lungs, where it is reduced to CO and water and is
2
exhaled; thus, hydrogen ions are inactivated and
exhaled.

3. During alkalosis, the pH increases and the

respiratory rate and depth decrease; CO is retained
2
and carbonic acid increases to neutralize and decrease
the strength of excess bicarbonate.
4. The action of the lungs is reversible in controlling an
excess or deficit.
5. The lungs can hold hydrogen ions until the deficit is
corrected or can inactivate hydrogen ions, changing
the ions to water molecules to be exhaled along with
CO , thus correcting the excess.
2
6. The process of correcting a deficit or excess takes 10 to
30 seconds to complete.
7. The lungs are capable of inactivating only hydrogen
ions carried by carbonic acid; excess hydrogen ions
created by other mechanisms must be excreted by the
kidneys.

Monitor the client’s respiratory status closely. During acidosis,

the respiratory rate and depth increase in an attempt to exhale acids.
During alkalosis, the respiratory rate and depth decrease; CO is
2
retained to neutralize and decrease the strength of excess bicarbonate.
D. Kidneys
1. The kidneys provide a more inclusive corrective
response to acid-base disturbances than other
corrective mechanisms, even though the renal
excretion of acids and alkalis occurs more slowly.
2. Compensation requires a few hours to several days;

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