74: Acid Base Physio Flashcards
Write the Henderson-Hasselback equation:
pH = 6.1 + log [HCO3-]/0.03PCO2
pH = pK + log[HCO3-]/[CO2]
You can use this equation on the Davenport graph, and as long as you have 2 values, you can calculate the third.
In the regulation of blood pH, the _____ sets the level of bicarbonate (numerator) whereas the _____ sets the partial pressure of carbon dioxide (denominator).
pH = 6.1 + log [HCO3-]/0.03PCO2
In the regulation of blood pH, the kidney sets the level of bicarbonate (numerator) whereas the lung sets the partial pressure of carbon dioxide (denominator).
Normal ventilation is ___ mmHg
Normal blood pH is ___ & normal bicarbonate is 24mM.
In davenport graph, each line at ___ PCO2 is an isobar, or metabolic line. When PCO2 changes, you hop onto ___ isobaric line for the corresponding change in PCO2.
See Davenport graph on slide 3.
Normal ventilation is 40 mmHg
Normal blood pH is 7.4 & normal bicarbonate is 24mM.
In davenport graph, each line at constant PCO2 is an isobar, or metabolic line. When PCO2 changes, you hop onto another isobaric line for the corresponding change in PCO2.
See Davenport graph on slide 3.
CO2 + ___ ↔ H2CO3 ↔ H+ + ___
Hyperventilation ___ CO2 = respiratory ___
Hypoventilation ___ CO2 = respiratory ___
CO2 (lungs) + H20 ↔ H2CO3 ↔ H+ + HCO3- (kidney)
Hyperventilation decreases CO2 = respiratory alkalosis
Hypoventilation increases CO2 = respiratory acidosis
CO2 + ___ ↔ H2CO3 ↔ H+ + ___
As you increase PCO2 the bicarb and proton concentration goes ___ so pH goes ___.
This relationship is displayed on the Davenport graph by lines called respiratory lines, where PCO2 is ___.
See slide 5.
CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3-
Note that H2CO3 = carbonic acid
As you increase PCO2 the bicarb and proton concentration goes up so pH goes down.
This relationship is displayed on the Davenport graph by lines called respiratory lines, where PCO2 is changing.
Causes of ___ ventilation include:
COPD: Emphysema Asthma Narcotics/Anesthesia Airway Obstruction Lung Collapse Muscular Dystrophy or Paralysis Pneumonia Bronchitis Severe Pulmonary Edema
All of these depress ventilation and cause respiratory ___.
In chronic respiratory acidosis, the kidney will secrete protons into urine and ___ more bicarbonate to raise blood bicarbonate & try to ___ pH closer to homeostasis.
Causes of hypoventilation include:
COPD: Emphysema Asthma Narcotics/Anesthesia Airway Obstruction Lung Collapse Muscular Dystrophy or Paralysis Pneumonia Bronchitis Severe Pulmonary Edema
All of these depress ventilation and cause respiratory acidosis.
In chronic respiratory acidosis, the kidney will secrete protons into urine and reabsorb more bicarbonate to raise blood bicarbonate & try to elevate pH closer to homeostasis.
During respiratory acidosis, bicarbonate is ___ while pH is falling.
During renal compensation to respiratory acidosis, bicarbonate is ___ further while pH is rising.
So pH can either rise or fall when bicarbonate is ___.
Conclusion: the pH of the blood depends on the ___ concentration ONLY, not the concentration of bicarbonate!
So when checking for blood pH, do not look @ ___, only ___ concentration.
During respiratory acidosis, bicarbonate is increasing while pH is falling.
During renal compensation to respiratory acidosis, bicarbonate is increasing further while pH is rising.
So pH can either rise or fall when bicarbonate is increasing.
Conclusion: the pH of the blood depends on the proton concentration ONLY, not the concentration of bicarbonate!
So when checking for blood pH, do not look @ bicarb, only proton concentration.
Causes of hyperventilation that cause respiratory ___ include:
Ventilator set too high in ICU
Anxiety attack
Trauma to respiratory center in brain
Brain tumor
In chronic respiratory alkalosis, the kidney will reabsorb ___ bicarbonate to decrease blood bicarbonate & try to ___ pH closer to homeostasis.
See slides 6 & 8 to see how kidney compensates for respiratory disorders (purple).
Causes of hyperventilation that cause respiratory alkalosis include:
Ventilator set too high in ICU
Anxiety attack
Trauma to respiratory center in brain
Brain tumor
In chronic respiratory alkalosis, the kidney will reabsorb less bicarbonate to decrease blood bicarbonate & try to decrease pH closer to homeostasis.
In respiratory alkalosis and acidosis the PCO2 is ___, but in metabolic acidosis and alkalosis the PCO2 is ___.
In respiratory alkalosis and acidosis the PCO2 is changing, but in metabolic acidosis and alkalosis the PCO2 is normal.
Causes of metabolic ___ include:
ECF Volume Contraction: Chloride Responsive to saline infusion (treatment to decrease pH)** Vomiting (decreases protons) Gastric tubes in Px Excess diuretics
ECF Volume Expansion
Chloride Resistant to saline infusion
Hyperaldosteronism
There are 2 types of metabolic alkalosis, chloride responsive and chloride resistant.
Causes of metabolic alkalosis include:
ECF Volume Contraction: Chloride Responsive to saline infusion (treatment to decrease pH)** Vomiting (decreases protons) Gastric tubes in Px Excess diuretics
ECF Volume Expansion
Chloride Resistant to saline infusion
Hyperaldosteronism
There are 2 types of metabolic alkalosis, chloride responsive and chloride resistant.
Excess diuretics (loop of henle diuretics) cause volume contraction and metabolic alkalosis by ___ reabsorption of solutes so that blood pressure decreases.
Excess diuretics ___ the loss of salt and fluid which ___ RAAS activity & ___ renal proton secretion; therefore, plasma bicarbonate ___ and blood becomes basic.
In ECF volume contraction a treatment is ___ infusion (___ responsive = treatment to decrease pH)**
Excess diuretics (loop of henle diuretics) cause volume contraction and metabolic alkalosis by preventing reabsorption of solutes so that blood pressure decreases.
Excess diuretics increase the loss of salt and fluid which increases RAAS activity & increases renal proton secretion; therefore, plasma bicarbonate increases and blood becomes basic.
In ECF volume contraction a treatment is saline infusion (chloride responsive = treatment to decrease pH)**
Metabolic acidosis is caused by having too little bicarbonate. The compensatory mechanism is ___ ventilation, to increase blood pH.
Metabolic acidosis is caused by having too little bicarbonate. The compensatory mechanism is hyperventilation, to increase blood pH.
CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3-
Metabolic alkalosis is caused by having too much bicarbonate. The compensatory mechanism is ___ ventilation, to decrease blood pH.
Metabolic alkalosis is caused by having too much bicarbonate. The compensatory mechanism is hypoventilation, to decrease blood pH.
CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3-
See slides 10 & 12 to view compensation of metabolic acidosis and alkalosis.
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There are 2 types of metabolic acidosis:
Anion gap metabolic acidosis refers to when the anion gap is ___.
Hyperchloremic metabolic acidosis refers to when the anion gap is not elevated & there is ___ chloride.
There are 2 types of metabolic acidosis:
Anion gap metabolic acidosis refers to when the anion gap is elevated
Hyperchloremic metabolic acidosis refers to when the anion gap is not elevated & there is increased chloride.
