FORM & FUNCTION (Acid Base Disturbances) Flashcards
4 types of disturbances
- Metabolic ([HCO3-]) or Respiratory (PCO2)
- Acidosis or Alkalosis
Acidemia
-pH<7.4
-caused by acidosis
-higher PCO2/lower HCO3-
alkalemia
-pH>7.4
-caused by alkalosis
-lower PCO2/higher HCO3-
normal ratio of HCO3-/0.03xPCO2
=20
-less than 20: acidemia
-more than 20: alkalemia
Le Chatelier’s principle
-disturbance to a system equillibrium shifts the equilibrium in the direction that counteracts the changes
*system always wants to re-establish equilibruim
If CO2/H2CO3 increases
-shift will favour formation of H+ and HCO3-
-as H goes us, the environment becomes more acidic
If H+/HCO3- increase
-shift will favour increase in CO2/H2CO3
Respiratory acidosis
- Causes: hypoventilation (reduced rate and depth of breathing)
- Change: increase in CO2 ->increase in PCO2
- Shift: to the right=increase H+ and HCO3- (decreases pH)
*renal compensatin via increased HCO3- reabsorption (slow process
Respiratory alkalosis
- Cause: hyperventilation (increased rate and depth of breathing)
- “Change”: decreased CO2 (decrease PCO2)
- Shift: left=decrease H+ and HCO3- (more basic)
*renal compensation to reduce HCO3- reabsorption (slow process)
metabolic acidosis
- Cause: overproduction of lactic acid from exercise
- “Change”: increase H+ (decrease in HCO3-)
- Shift: left
*respiratory compensation via in depth and increased rate (hyperventilation) to reduce PCO2 ->reduces H+ formations
Metabolic alkalosis
- Causes: vomiting->loss stomach acid->increase HCO3- in plasma
- “Change”: increased HCO3-
- Shift: right, going to get more proteins deficit as HCO3 will deplete it due to high levels
*chemoreceptors detect a drop in H+ ->respiratory suppression to increase PCO2 ->increases H+ formation
respiratory vs. renal compensation
-respiratory is faster
additional underlying factors that hinder compensation responses
-renal failure
-pulmonary disease
-depressant drugs of the respiratory center
mixed disturbances
-two or more acid-base disturbance together
Ex. unregulated diabetic animals
anion gap
-difference in concentration of major cations and anions
-due to various organic cations, anions and proteins
*totatal charge is neutral
cations
Na+
K+
anions
-Cl-
-HCO3-
anion gap ratio
-allows for estimation of unmeasured molecules
-can provide info on the type of metabolic disturbance
increase in anion gap
-useful indicator of metabolic acidosis
Ex. excess lactic acid in blood
>increased from the decrease in HCO3-
>total charge still neutral since lactate anion also increase
*due to increased organic anions (“randoms”)
decrease in anion gap
-could signal cation anomally (cation disturbance) or metabolic alkalosis (increase bicarbonate)
anion gap, but normal
-metabolic acidosis (ex. diarrhea cause HCO3- loss)
>kidney compensates increases Cl- reabsorption to maintain a neutral charge
*hypercholremia metabolic acidosis
Metabolic acidosis determinaion
+increased anion gap=caused by excess organic anion (lactic acid)
+no change in anion gap=loss of HCO3- compensated by Cl- (diarrhea)