acid base and pH regulation Flashcards
what is the normal level of plasma pH
7.4
what does acid base balance affect
- enzyme function
- cellular function
- CNS and CVS function
- oxygen transport
- electrolyte balance
- acid waste elimination
how is enzyme function affected by acid base
- catalyst for biochemical
- pH changes denatures and dysfunction hindering metabolism
how is cellular function affected by acid base
- needed for cell integrity and function
- have pH dependent transport mechanisms
- ph change hinder cell function and cause death
how is CNS and CVS function affected by acid base
- influences contractility of heart and response of blood vessels
- acidosis and alkalosis cause neuronal dysfunction
how is oxygen transport affected by acid base
- affect haemoglobin affinity
- alters O2 carrying capacity
how is electrolyte balance affected by acid base
- affects regulation of electrolytes
- concentration needed for nerve conduction, muscle function and fluid balance
how is acid waste elimination affected by acid base
- metabolism produces acid waste
- elimination through lungs and kidneys prevents accumulation
what is pH
measure of how basic or acidic a solution is
what is acid
substance that donates protons
what is a base
substance that accepts protons
what is a buffer
solution which reduces the affect of adding or removing H+
what is HCO3-
bicarbonate acts as a base accepts excess H+ to regulate pH
what does the henderson-hasselbalch equation consider
- changing concentration of CO2 or HCO3 alters the pH
- increase arterial PCO2 drops arterial pH
what is the henderson -hasselbalch equation
pH = 6.1+ log [HCO3}/o.o3 x PCO2
how do changes in CO2, H+ and HCO3 affect each other
^ CO2 + H2O <-> H2CO3 <-> HCO3 + ^ H+
affect of decreased PaCO2
increases pH
affects of increase PaCo2
decreased pH
affects of increase HCO3
increased pH
affects of decreased HCO3
decrease pH
what is acidosis
increase of hydrogen ions and a reduction of bicarbonate
what is alkalosis
decrease in hydrogen ion and increase of bicarbonate
what is respiratory acidosis
- CO2 retention from hypoventilation
- increasing H+
what are causes of respiratory acidosis
resp conditions with CO2 retention
what is metabolic acidosis
all types of acidosis from excess CO2 in body fluids
what causes metabolic acidosis
- increase acid production
- loss of bicarbonate
- decrease acid excretion
what is respiratory alkalosis
excessive CO2 lost from the body from hyperventilation
what causes respiratory alkalosis
- hypoxia
- hyperventilation
what is metabolic alkalosis
reduction in plasma caused by relative deficiency in no carbonic acids
what causes metabolic alkalosis
- hydrogen loss
- excess HCO3 ingestion
what are the differentiation values for acidosis
- metabolic = HCO3 <24
- respiratory = PaCO2 >6
what are the differential values for alkalosis
- metabolic = HCO3 >24
- respiratory = PaCO2 <4.7
how can COPD cause mixed metabolic and respiratory acidosis
- hypoxic hypoxia increase lactic acid = decreases HCO3
- decreased ventilation increase PaCO2 = increases PaCO2
what causes H+ gain
- acid production
- HCO3 loss in stool
- ingestion of acid
what causes H+ loss
- acidic gastric acid fluid in vomiting
- loss of H+ in urine
how is H+ maintained in normal limits
- H+ with blood buffer or intracellular buffer
- reduction of H2CO3 by CO2 elimination
- renal elimination of H+
- H+ moves into cells in exchange for K+
how is normal plasma ph maintained
- chemical buffer of the blood cells
- renal regulation of H+ and HCO3
- respiratory regulation
how does the chemical buffer system work
- reduces affect of adding or removing H+
- ions are removed from the solution but not eliminated
- incorporated into a buffer pair
how does the bicarbonate buffer system work
- increase or decrease H+
- cant buffer pH changes cause by its own system
how does the haemoglobin buffer work
RBCs buffer H+ from metabolically produced CO2
how does protein buffer system work
- albumin
- has both acidic and basic groups that buffer
how does the phosphate buffer system work
- intracellular and urinary buffer
- excess phosphate filtered through the kidneys
what is the respiratory regulation of ph
- alters pulmonary ventilation and so alters excretion of H+, generating CO2
what is the respiratory regulation when there is an increase in arterial H+
- increase pulmonary ventilation
- increase CO2 blown off
what is the respiratory regulation when there is a decrease in arterial H+
- decreased pulmonary ventilation
- increased CO2 accumulation
what stimulate the peripheral chemoreceptors
- decreased PaO2
- increased H+
- increased PaCO2
what stimulates the central chemoreceptors
- increase H+
- increased PaCO2
how does renal regulation of pH occur
- removes H+ and adds HCO3 to body fluids
- ammonia secretion
what is the renal regulation when there is an increase in PaCO2
- increased renal reabsorption or generation of HCO3
- increase in Plasma
- increase in pH
what is the renal regulation when there is a decrease in PaCO2
- increased renal excretion of HCO3
- decreased plasma
- decreased pH
how is hydrogen secretion increased
- increase secretion into renal tubes so more in urine
- increase HCO3 reabsorption into the blood
- decreases pH
how is hydrogen secretion decreased
- decrease H+ secretion into renal tubules
- decrease HCO3 reabsorption into blood
- increase pH
what is the renal compensation in compensatory chronic respiratory acidosis
- decreased urea production and increased glutamate, which becomes ammonia and HCO3
what is the renal compensation in compensatory chronic respiratory alkalosis
- increase in activity of type b intercalated cells
- help to secrete HCO3 into tubule lumens to increase concentration
what is the renal response in respiratory acidosis
- increases H+ excretion
- increases HCO3 reabsorption and regeneration
what is the respiratory and renal response in metabolic acidosis
- resps = decrease pH and increase CO2, increase vents
- renal = increase H+ excretion
what is the renal response in respiratory alkalosis
increase HCO3 excretion
what is the renal and respiratory responses in metabolic alkalosis
- resps = decrease ventilation and increase CO2
- renal = increase HCO3 excretion
what does ROME stand for in ph balance
Respiratory
Opposite
Metabolic
Equal
what is type I respiratory failure
- failure to oxygenate
- hypoxemia without hypercapnia
- low PO2
- normal PCO2
what is type II respiratory failure
- failure of alveolar ventilation
- hypoxaemia with hypercapnia
- PO2 low
- PCO2 high
how does severe asthma cause respiratory acidosis
hypoxemia -> reduce tissue oxygenation -> anaerobic metabolism -> lactic acidosis
how does severe asthma lead to respiratory alkalosis
hyperventilation -> hypocapnia -> respiratory alkalosis
what order do you use to interpret bloods for oxygenation and respiratory failure
- oxygenation (low = resps, high = metabolic)
- alkalosis or acidosis
(both for which respiratory failure) - work out which pathway