Physiology- Acid Base balance Flashcards
what is the only thing to contribute to pH?
H+ ions
how do you produce respiratory acid?
increasing or decreasing respiration, can change amount of co2 in body:
CO2 + H2O « H2CO3 « H+ + HCO3-
how do you produce metabolic acid?
Via metabolism through
- Inorganic acids eg sulphuric acid from sulphur containing amino acids
- Organic acids eg lactic acid, fatty acids
what are the most important:
- ECF buffers
- ICF buffers
- ECF: HCO3
- ICF:
Proteins
Organic & inorganic phosphates
Hb in RBCs
why are intracellular buffers v important?
- ECF and ICF systems are linked to each other- if there is acid loading, will produce pH gradient over membrane so drive to pump protons into cells at a higher extent than normal
- BUT need to maintain electroneutrality so H+ pumped into cell exchanged for K+
Therefore, in acidosis= HYPERKALAEMIA –> danger of ventricular fibrillation
by what mechanisms does the kidney regulate HCO3?
- reabsorbing filtered HCO3 in proximal tubule
- generating new HCO3 in distal tubule
- excretion of ammonia
- in proximal and distal tubule
- produces new bicarb and excretes H+
what does resp acidosis result from?
- Results from reduced ventilation and thus retention of co2
- Increase in HCO3
causes of respiratory acidosis?
- acute: drugs ie opioids, barbiturates or obstruction of major pathways
- chronic: lung disease
what does respiratory alkalosis result from?
- Due to increased ventilation and co2 blown off
- HCO3 reduced
causes of respiratory alkalosis?
- acute: hyperventilation, aspirin, first descent to altitude
- chronic: long term residence at altitude
what does metabolic acidosis result from and what is the compensatory mechanism?
- reduced HCO3
- to compensate: increased ventilation (kussmaul breathing) to blow off more co2
Causes of metabolic acidosis?
- increased H+ buffering
- increased loss of HCO3 ie diarrhoea
- reduced excretion of H+ ie renal failure
what does metabolic alkalosis result from and what is the compensatory mechanism?
- [HCO3-] must have increased
- to compensate: Pco2 will rise to protect the pH
causes of metabolic alkalosis?
- Increased H+ ion loss ie vomiting
- Massive blood transfusion
- Bank blood contains citrate to stop coagulation, which is converted to bicarbonate
- Need at least 8 units to have this effect
summary table of acid/base disoders: fill out
