Blood Gases Flashcards
Definition of an acid
Substance that can donate hydrogen ions when dissolved in water
Definition of base
a substance that accepts ions in water
Normal pH of the body
7.35-7.45
What buffer system works to balance pH in the body?
Carbonic acid/bicarbonate buffer system
Henderson-hasselbalch equation
pH = pKa + log (cA-/cHA)
What is the pLa
The pH where there is an equal amount of protonated and unprotonated species
What does carbonic anhydrase do
catalyzes the combination of CO2 and H2O to form carbonic acid that dissociates into H+ and bicarbonate
What does the kidney do in the bicarbonate buffer system
Regulates excretion of both acid and base, as well as reabsorbing bicarbonate
What is Henry’s law
The amount of sparingly soluble gas dissolved in a liquid is proportional to the partial pressure of the gas over the liquid
C=axP
Partial pressure
pressure that a gas would exert if it were the only gas present. This contributes to the overall pressure of a gas
volume/mole fraction of a gas x total pressure
How do lungs maintain homeostasis
hyperventilation and hypoventilation
how do kidneys maintain homeostasis
changes bicarbonate concentration in the blood. Excretion of H+ and retention of bicarbonate.
Reference range for pCO2
35-45mmHg
85-105 mmol/L
Ref. range for HCO3-
22-29mmol/L
Ref range for total CO2
23-27mmol/L
Ref range for SO2 and O2Hb
> 95%
What is the response to maintain acid base balance called
Compensation
What is primary respiratory acidosis/alkalosis
a disorder that is caused by ventilatory dysfunction resulting in a change in the pCO2
What is non-respiratory/metabolic acidosis/alkalosis
a disorder that results from a change in bicarbonate levels which has a renal or metabolic origin
Metaolic acidosis
-Increased anion gap
-loss of basic fluids/diarrhea
-renal failure and renal tubular acidosis
-pancreatitis
Respiratory depression(acidosis)
-narcotics and barbituates
-CNS trauma, tumor
-infection of CNS
Conditions of lungs(acidosis)
-COPD
-pulmonary fibrosis
-tumor
-pleural effusion
-acute respiratory distress
Other causes of respiratory acidosis
abdominal distention, extreme obesity, sleep apnea
Respiratory acidosis general definition
primary bicarbonate deficit throwing of the 20:1 ratio. Can happen bc of inc production of organic acids such as ketoacidosis