Other (specialties) Flashcards
Which type of acids are generated from aerobic metabolism and CO2 production
Volatile acids
Which types of acids are generated by non-aerobic metabolism eg. lactic acid, H2SO4
Non-volatile acids
Volatile acids are secreted by which tissues?
Lungs
Non-volatile acids are secreted by which tissues?
Kidneys
What are the 3 main buffer systems?
- Bicarbonate
- Phosphate
- Protein
Is it a metabolic or respiratory cause if base excess is outside of the normal range?
Metabolic
What is a buffer?
Any substance that can reversibly bind H+
Explain the physiology of the bicarbonate buffer system (inc. substances involved)
Connects lungs control of CO2 to kidney control of HCO3. Systems can compensate for each other.
Explain the physiology of the phosphate buffer system (inc. substances involved)
Picks up excessive H+ in urine lumen and excretes it in urine.
Explain the physiology of the protein buffer system (inc. substances involved)
Mostly an intracellular process involving haemoglobin.
Which has a faster response to H+ imbalances - lungs or kidneys?
Lungs.
Why is urine acidic?
Kidneys control H+ excretion: they must excrete 70-100ml/day of H+ from non-volatile acids
What are the two main processes by which kidneys regulate extracellular pH?
- Reabsorption of filtered HCO3
2. Excretion of H+
Where in the kidney is filtered HCO3 reabsorbed?
Proximal convoluted tubule (PCT)
How is H+ pumped into the lumen?
Via H+-ATPase pump
How would pH, PCO2 and HCO3 look in respiratory acidosis?
pH = low pCO2 = high HCO3 = normal (or high if compensated)
(5) causes of respiratory acidosis
- COPD
- Decompensation in other resp. diseases e.g. asthma or pulmonary oedema
- Neuromuscular diseases
- Obesity (hypoventilation syndrome)
- Sedative drugs e.g. benzos, opioids
How would pH, PCO2 and HCO3 look in respiratory alkalosis?
pH = high pCO2 = low HCo3 = normal
(4) causes of respiratory alkalosis
- Anxiety/pain
- Hyperventilation
- High altitude
- PE or pneumothorax
How would pH, PCO2 and HCO3 look in metabolic acidosis?
pH = low pCO2 = normal/low HCO3 = low
(5) causes of metabolic acidosis
- Addition of exogenous acid (e.g. methanol)
- Addition of endogenous acid (e.g. lactic acid, renal failure)
- Failure of H+ excretion
- Loss of HCO3+ (e.g. diarrhoea)
- DKA
Why is CO2 normal/low in metabolic acidosis?
Compensation by lungs –> increased ventilation in an attempt to reduce CO2
How would pH, PCO2 and HCO3 look in metabolic alkalosis?
pH = high pCO2 = normal/high HCO3 = high
(4) causes of metabolic alkalosis
- addition of alkali substance (HCO3)
- Excessive H+ loss (e.g. vomiting, renal loss)
- Excess aldosterone (e.g. dehydration)
- Cushing’s/Conn’s syndrome
