Acid-Base Physiology Flashcards
What range of pH can the body tolerate?
6.8-7.8
What is the normal plasma bicarbonate concentration?
24 mEq/L
What is the equation for the bicarbonate buffer system?
CO2 + H2O H2CO3 H+ + HCO3-
What is the formula for calculating hydrogen concentration?
[H+] = 24 PCO2/[HCO3-]
Bicarbonate decrease causes…
Metabolic acidosis
Bicarbonate increase causes…
Metabolic alkalosis
Decreased CO2 causes…
Respiratory alkalosis
Increased CO2 causes…
Respiratory acidosis
How does the body compensate for respiratory disorders besides adjusting lung activity?
Bicarbonate concentration 1-2 days
HCO3 levels always change with…
PCO2
What are some causes of metabolic acidosis?
Decreased acid excretion; direct bicarb loss from GI/urine; increased acid generation; renal failure leading to inability to excrete acid as NH4+
What is the most common cause of chronic respiratory acidosis?
COPD
What are some causes of metabolic alkalosis?
Loss of H through GI (vomiting) or urine (diuretics)
Excessive urinary net acid excretion
What is the primary disturbance in metabolic acidosis?
HCO3- depleted to buffer extra acid
What is the respiratoy compensation for metabolic acidosis?
Hyperventilation
What is the kidney compensation for metabolic acidosis?
Increase H+ excretion as NH4+
Increase reabsorb/production of HCO3-
What is the formula for the serum anion gap?
[Na] - [Cl] - [HCO3-] = anion gap
What are the unmeasured anions that the serum anion gap is measuring?
Phosphate
Citrate
Sulfate
PROTEIN
When does the serum anion gap increase in metabolic acidosis?
When concentration of an unmeasured anion increases to help replace HCO3-
When is the serum anion gap normal in metabolic acidosis?
When the concentration of Cl- is what compensates for HCO3-
What is the primary disturbance in metabolic alkalosis?
HCO3- increases in response to a decrease in H+
What is the respiratory compensation for metabolic alkalosis?
Hypoventilation
How does the kidney respond to metabolic alkalosis?
Increase HCO3- excretion because the excess filtered load is above ability to reabsorb
What is the primary disturbance in respiratory acidosis?
Increased arterial PCO2, which through mass action is converted to H+ and HCO3-
What is the renal compensation for respiratory acidosis?
Increase H+ excretion as NH4+; increase reabsorption of HCO3-
What is the primary disturbance in respiratory alkalosis?
Decreased arterial PCO2 due to hyperventilation, which causes decreased H+ and HCO3-
What is the renal compensation for respiratory alkalosis?
Decreased H+ excretion and increased reabsorption of new HCO3-
Does the plasma anion gap change in respiratory acid-base disorders?
No
Alpha cells do what to change acid base balance
Use active transport to eliminate H into urine. The H is generated from HCO3- in interstitium by CA.
What is the urinary anion gap?
Na + K - Cl
