Flashcards
Acid Base Balance
Cards in this deck (21)
- 1define pKathe pH at which 50% is ionised and 50% is unionised in the reaction
- 2how can the absolute levels of bicarbonate be changed?by changes to breathing as:
H2O + CO2 → H2CO3
Increased CO2 leads to more H2CO3 and vice versa - 3what chemical does respiratory acid base disturbances refer to ?CO2
- 4what chemical does metabolic acid base disturbance refer to?HCO3-
- 5what can an acidosis be caused by?fall in HCO3-
increased PCO2 - 6what can cause an alkalosis?increased HCO3-
fall in PCO2 - 7describe the ways in which the kidneys and lungs compensate for acid base disturbances?kidneys - alter excretion of bicarbonate - takes 2-3 days
lungs - alter Ventilation - happens quickly - 8how is PCO2 increased?hypoventilation (less CO2 being blown away)
V/Q mismatch - 9how does an increase in PCO2 lead to a lowering of pH?from the hendersson - hasselbach equation, an increase in PCO2 leads to an increase in H+ so a lowering of pH
thus plasma levels of HCO3- increase to try and compensate fro increased H+ - 10how is a respiratory acidosis compensated for?by the kidneys
increased HCO3- reabsorption and increased HCO3- production raises pH back towards normal. - 11what are some diseases causes of respiratory acidosis?- COPD
- blocked airway
- lung collapse
- injury to chest wall
- drugs reducing respiratory drive - 12how does respiratory alkalosis result in an increase in pH?results from a decrease in PCO2 caused by alveolar hyperventilation (more CO2 being blown away)
this causes a decrease in h+ concentration and so an increase in ph? - 13how is a respiratory alkalosis compensated for?by kidneys
reduced HCO3- reabsorption and production leads to falling HCO3- plasma levels, compensating for lowered H+, moving pH back to normal. - 14what are the causes behind a respiratory alkalosis?increased ventilation from hypoxic drive in pneumonia
diffuse interstitial lung diseases
high altitude
mechanical ventilation
hyperventilation - brainstem damage, infection driving fever - 15does PCO2 change during renal compensation?no
- 16what results in a metabolic acidosis?an excess in H+ which reduces HCO3- levels (equation shifts to left)
respiration is unaffected therefore PCO2 is initially normal - 17how is metabolic acidosis compensated for?by the lungs
the lower pH is detected by peripheral chemoreceptors and causes an increase in ventilation which lowers PCO2
bicarbonate equation is driven to the left, lowering H+ and HCO3- conc further
this decrease in H+ conc moves pH back towards normal
Respiratory compensation cannot fully correct the pH, HCO3 and H+,
so excess H+ needs to be removed or HCO3- restored (by slow renal comp) - 18what disorders cause metabolic acidosis?loss of HCO3- eg. from gut in diarrhoea
exogenous acid overloading
failure to secrete H+ eg in renal failure - 19what results in a metabolic alkalosis?increase in HCO3- concentration or a fall in H+
removing H+ from the equation drives the reaction to the right and increases HCO3-.
lowering of H+ conc, raises ph with PCO2 initially being normal - 20how is a metabolic alkalosis compensated for?increase in pH detected by peripheral chemoreceptors which decreases ventilation - raises PCO2
equation is driven further to the right, increasing H+ and HCO3- levels and decreases pH
Respiratory compensation is often small (or even absent) – ventilation cannot reduce enough to correct imbalance.
- Renal response is to secrete less H+ - 21what disorders cause a metabolic alkalosis?vomiting - loss of HCl from stomach
- ingestion of alkali substances
- potassium depletion (diuretics)
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- Physiology (Respiratory) Flashcards on Acid Base Balance, created by hazel wilkie on 05/12/2017.
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- hazel wilkie
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