Acid base balance Flashcards
Normal pH range
7.35 (venous)- 7.45 (arterial)
Concentration of H+ in plasma
45-35nmoles/litre
What physiological effects do fluctuations in H+ have?
excitability if muscle and nerve, enzyme activates, potassium levels (rise in H cause K removal)
pH of gastric secretions, CSF and pancreatic secretions
0.7, 7.3, 8.1
Where are buffers present?
Blood, extracellular fluid, intracellular fluid, urine
Henderson Hasselbalch equation
pH=pK+ log [HCO3/H2CO3] pK- constant at 37 degrees= 6.1
SIDs likely to be caused by
Don’t have normal control of ventilation, so higher concentration of carotid body dopamine and NA, some SID babies lack serotonergic neruones
How does hypoxia effect sensitivity to CO2 and low pH?
They become more sensitive so more of a drive for ventilation
How does pH effect sensitivity to CO2?
Increases sensitivity so more of a drive for ventilation
What change in CO2 can double ventilation through central chemoreceptors?
40-45mmHg
What did Isodore Lesson do?
perfused cerebral ventricles with acidic solution
3 mechanisms fo renal changes to acid/alkali
Bicarbonate handling, urine acidification, ammonia synthesis
What percent do each mechanism do for base conservation in kidney?
Acidification of ruin- 25%, Ammonification -75%
How does ammonia synthesis occur in renal?
Glutamine to a keto-glutamate makes 2x NH3 and 2xH. H moves out via NHE and NH3 moves out. NH3 moves out of cells and binds to H+ outside of cells so it is then stuck and excreted
Give examples of mixed disorders
Alcoholic patients, asthma (respiratory acidosis and lactic acidosis), COPD( treated with diuretics which promote metabolic alkalosis but they have respiratory acidosis), Salicylate poisoning(aspirin, respiratory alkalosis as it stimulates respiratory centres and metabolic acidosis from drug)
