Acid Base Balance Flashcards
What is the normal value range of PH?
PH 7.4
Range 7.37 - 7.43
What is the normal value range for pC02?
- 3 kPa / 40mmHg
4. 8-5.9
What si the normal value range for HC03?
24 mmoles (22-26)
Where does the increase in H in respiratory acidosis come from?
Formation of H from excess C02
(Normally compensate by increasing ventilation to blow of C02 but with impaired lung function the H builds up as ventilation is impaired)
Where does the increase in H in metabolic acidosis come from?
Inorganic acids such as sulphuric acid (H2S04) and phosphoric acid produced from phospholipids
Organic acids such as lactic acid and fatty acids
What is responsible for minimizing changes in PH ?
Buffers
What is the main extracellular buffer?
HC03 - bicarbonate
What is responsible for the excretion of H?
The kidneys -
Excretion of H by the kidneys is coupled to the regulation of plasma HC03
What are the intracellular buffers?
Proteins, organic and inorganic phosphates
In erythrocytes - haemoglobin
What is the function of intracellular buffers?
Maintain electrochemical neutrality
H must be accompanied by K
Does acidosis result in hypo or hyperkalaemia and how?
Hyperkalaemia
Increase in H dives k out of the cell into ECF = hyperkalaemia = VF & death
What is responsible for the control of pC02?
Respiratory system
How does the kidney regulate HC03?
Reabsorbing filtered HC03
Generating new HC03 with net excretion of H
What is the PH value range of urine?
4.5 - 5.0 (max 8.0)
How does the kidneys excrete H?
Excreted as ammonium NH4
What effect on pC02 and HCO3 does respiratory acidosis cause?
Increase in pC02 (primary problem)
Tries to compensate by increasing HC03
What effect on pCO2 and HC03 does respiratory alkalosis cause and how?
Decrease in pC02 (primary problem)
Tries to compensate by decreasing HC03
What effect on pC02 and HC03 does metabolic acidosis cause and how?
Decrease in HC03 (primary problem)
Tries to compensate by decreasing pC02 by hyperventillating to blow off more C02 = kaussmaul breathing
What effect on HC03 and pC02 does metabolic alkalosis cause and how?
Increased HC03 (primary problem) Tries to compensate by increasing pC02
What is kaussmaul breathing and in what situation is it found and why?
Heavy breathing - hyperventillating
Seen in metabolic acidosis i.e. diabetic ketoacidosis in an attempt to decrease pC02
What is the role of aldosterone in a bad case of vomiting and what effect does this have on PH?
The loss of NaCl and H20 in vomit = hypovolaemia
This stimulates aldosterone to increase reabsorption of Na in the distal tubule
The exchange ion for Na is H, therefore more H is excreted = worsening alkalosis
However in this case the hypovolaemia plays more importance than the PH imbalance
