ACID/BASE BALANCE

D. C. Mikulecky

CHEMICAL COMPOUNDS CAN BE PROTON DONORS OR ACCEPTORS

PROTON DONORS ARE ACIDS PROTON ACCEPTORS ARE BASES ACIDS AND BASES REACT TO

NEUTRALIZE EACH OTHER FORMING SALTS

HCl + NaOH NaCl + H2O

ACID + BASE SALT + WATER

Acidic Alkaline (Basic)

[OH -]

[H+]

NeutralpH

0 147

Acidosis Alkalosis

Normal7.35-7.45

Venous Blood Arterial Blood

6.8 8.0

7.4

H2CO3

HCO3-

H+

Na+ Cl-

AddHCl

Na+ Cl-

H+ Cl-

Unbuffered Salt Solution All protons are free

H2CO3: HCO3- Buffer

AddHCl

H2CO3

HCO3- + H+

Protons taken up as Carbonic Acid

Weak acid/salt systems act as a “sponge” for protons

As acidity tends to increase they take protons up

As acidity tends to decrease they release protons

Carbonic acid/Bicarbonate: Primary buffer against non-carbonic acid changes

Proteins: Primary ICF buffer, also ECF Hemoglobin: Primary buffer against

carbonic acid changes Phosphate: Urinary buffer, also ICF

Alterations in ventilation alter the rate of excretion of carbon dioxide

Alterations in the rate of carbon dioxide excretion cause alterations in pH through carbonic acid

This way the respiratory system can help control non-respiratory acidosis and alkalosis

Metabolic: Severe diarrhea, Diabetes mellitus, strenuous exercise, uremia

Respiratory: hypoventilation

Metabolic: Vomiting, ingestion of alkaline drugs

Respiratory: hyperventilation

Proton excretion

Bicarbonate excretion

Ammonia secretion