Biochemistry (ABGs) Flashcards
Why is the urine acidic?
60 milimol of H+ are produced by metabolism daily
Most/all of these needs to be excreted (in urine)
The [H+] is 35-45 nanomol/L
How can H+ be buffered in the body?
In the carbonic acid buffer
By haemoglobin
By phosphate
By ammonia
Why is the bicarbonate buffer so important?
All other buffer mechanisms reach equilibrium.
The bicarbonate system doesn’t as carbonic acid is removed as CO2
Name the acid and base components of the acid-base buffering.
pCO2 is the respiratory component.
HCO3- is the metabolic component.
Therefore in a respiratory disturbance, the primary change is in pCO2 & in a metabolic disturbance, the primary change is in HCO3-
Explain the following terms: Acidosis? Alkalosis? Acidaemia? Alkalemia?
Acidosis is elevated [H+] or a process tending to cause elevated [H+]
Alkalosis is decreased [H+] or a process tending to cause decreased [H+]
Acidaemia is an increase in blood [H+]
Alkalemia is an increase in blood [H+]
What is the metabolic compensation for respiratory acidosis?
Increased serum levels of HCO3-.
Increased secretion of H+ into the tubular lumen of the nephron.
State 3 common causes of respiratory acidosis.
Choking/airway obstruction
Bronchopneumonia
COPD
State 3 common causes of respiratory alkalosis.
Hysterical overbreathing/panic attack
Mechanical over-ventilation (iatrogenic)
Raised intracranial pressure
What is the respiratory compensation for metabolic acidosis?
Increasing breath rate to blow off CO2.
What is the respiratory compensation for metabolic alkalosis?
Decreased breath depth to retain CO2.
State 3 common causes of metabolic acidosis.
Impaired H+ excretion
Increased H+ production or ingestion
Loss of HCO3-
State 3 common causes of metabolic alkalosis.
Loss of H+ in the vomit.
Alkali ingestion
Potassium deficiency
Is it possible to overcompensate? (Context of ABGs)
No
