acid-base regulation week 3 Flashcards
What is the physiological pH
7.4 or slightly alkanline
Arrhenius Acids
acids increase H ions and bases increase OH ions
Bronstead Lowry
acids donate protons and bases accept protons( but do not necessarily increase OH- concentration)
Physiological sources of acid
- aerobic released CO2 and form carbonic acid (H2CO3) which is a weak acid
- carbonic anhydrase found on RBCs aids in speeding this rxn up.
- *Carbonic acid is a volatile acid ALL others are nonvolatile (metabolic acids)
- more CO2 =a potentially lowered pH in serum*
Difference between acidemia and acidosis
Acidemia is an overabundance of H+ ions in the blood
Acidosis refers to the syndrome of conditions in the body
What does blood pH tell you?
the ratio between the conjugate acid and base and NOT the amount of each
Ways the body controls pH
- Kidneys: remove H+, retains HCO3 (slow)
- Lungs can remove CO2 (rapid)
- Buffering: resists change in pH does not remove H+
(instantaneous) - These are reversible for alkalosis
systemic regulation of pH: lungs
increased H+(low pH) ions leads to increases ventilation
decreased H+(high pH) ions leads to decreased ventilation
-*remember lungs can only deal with volatile acid**
systemic regulation of pH: kidneys
- produce new bicarbonate by metabolizing glutamine to make ammonium and bicarbonate
- retention of bicarbonate
- can excrete acidic or basic urine
- can act on both volatile and nonvolatile acids
- if alkaline H+ can be retained and bicarbonate excreted
systemic regulation of pH: Buffer systems
- Bicarbonate: important in buffering EXTRAcellular fluid
- Phosphate: important in buffering the INTRAcellular fluid and in tubules of kidneys
- Proteins: generally neg charge and thus can absorb free H+ maintaining pH BOTH extra and intracellularly
eg: deoxy-hemoglobin in RBCs
what is Ka
the ratio of the concentration of component
pH=pKa +log[A-]/[HA]
what happens when conj. base is equal to acid?
pH =pKa
Buffers are most effective when this happens
Important concepts about buffers
- cannot change pH per se because they do not dispose of H+ of OH- ion
- they help resist a pH change
- Critical as a rapid acting first line of defense.
Most important intracellular pH regulators
- protein buffers, phosphate buffers, and ion transporters.
- pH is slightly more acidic inside cells (pH 7.1) which corresponds with phosphate buffer system pKa allowing peak efficiency
Respiratory acidosis
hypoventilation
decreased CO2 clearance
decreased serum pH
Increased renal excretion of H+ and retention of HCO3-
Respiratory alkalosis
hyperventilation
increased CO2 clearance
increased serum pH
decreased renal out put of H+ and retention of HCO3-
Systemic acidosis aka metabolic acidosis
abnormal loss of HCO3-
decreased serum pH
Increased ventilation to try and remove CO2
causes: diarrhea, renal problems, excessive lactic acid
Systemic alkalosis aka metabolic alkalosis
abnormal retention of HCO3-
increased serum pH
Respiratory depression to retain CO2
causes: excessive vomiting, hypokalemia, mineralocorticoids
what is a mixed acid base disorder
when more than one simple disturbance in acid-base exists
eg. heavy vomiting, causing loss of stomach acid and therefore a metabolic alkalosis due to too much HCO3-. However this vomiting can lead loss of blood volume, and thus an increase in lactic acid ultimately leading to metabolic acidosis.
Salicylate poisoning
involves acute stimulation of the respiratory center, causing respiratory alkalosis, but also results in an accumulation of endogenous, non volatile acids resulting in metabolic acidosis.
