Other (specialties)

Question 1

Which type of acids are generated from aerobic metabolism and CO2 production

Answer 1

Volatile acids

Question 2

Which types of acids are generated by non-aerobic metabolism eg. lactic acid, H2SO4

Answer 2

Non-volatile acids

Question 3

Volatile acids are secreted by which tissues?

Answer 3

Lungs

Question 4

Non-volatile acids are secreted by which tissues?

Answer 4

Kidneys

Question 5

What are the 3 main buffer systems?

Answer 5

1. Bicarbonate
2. Phosphate
3. Protein

Question 6

Is it a metabolic or respiratory cause if base excess is outside of the normal range?

Answer 6

Metabolic

Question 7

What is a buffer?

Answer 7

Any substance that can reversibly bind H+

Question 8

Explain the physiology of the bicarbonate buffer system (inc. substances involved)

Answer 8

Connects lungs control of CO2 to kidney control of HCO3. Systems can compensate for each other.

Question 9

Explain the physiology of the phosphate buffer system (inc. substances involved)

Answer 9

Picks up excessive H+ in urine lumen and excretes it in urine.

Question 10

Explain the physiology of the protein buffer system (inc. substances involved)

Answer 10

Mostly an intracellular process involving haemoglobin.

Question 11

Which has a faster response to H+ imbalances - lungs or kidneys?

Answer 11

Lungs.

Question 12

Why is urine acidic?

Answer 12

Kidneys control H+ excretion: they must excrete 70-100ml/day of H+ from non-volatile acids

Question 13

What are the two main processes by which kidneys regulate extracellular pH?

Answer 13

1. Reabsorption of filtered HCO3

2. Excretion of H+

Question 14

Where in the kidney is filtered HCO3 reabsorbed?

Answer 14

Proximal convoluted tubule (PCT)

Question 15

How is H+ pumped into the lumen?

Answer 15

Via H+-ATPase pump

Question 16

How would pH, PCO2 and HCO3 look in respiratory acidosis?

Answer 16

pH = low
pCO2 = high 
HCO3 = normal (or high if compensated)

Question 17

(5) causes of respiratory acidosis

Answer 17

• COPD
• Decompensation in other resp. diseases e.g. asthma or pulmonary oedema
• Neuromuscular diseases
• Obesity (hypoventilation syndrome)
• Sedative drugs e.g. benzos, opioids

Question 18

How would pH, PCO2 and HCO3 look in respiratory alkalosis?

Answer 18

pH = high 
pCO2 = low
HCo3 = normal

Question 19

(4) causes of respiratory alkalosis

Answer 19

• Anxiety/pain
• Hyperventilation
• High altitude
• PE or pneumothorax

Question 20

How would pH, PCO2 and HCO3 look in metabolic acidosis?

Answer 20

pH = low
pCO2 = normal/low
HCO3 = low

Question 21

(5) causes of metabolic acidosis

Answer 21

• 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

Question 22

Why is CO2 normal/low in metabolic acidosis?

Answer 22

Compensation by lungs –> increased ventilation in an attempt to reduce CO2

Question 23

How would pH, PCO2 and HCO3 look in metabolic alkalosis?

Answer 23

pH = high 
pCO2 = normal/high
HCO3 = high

Question 24

(4) causes of metabolic alkalosis

Answer 24

• addition of alkali substance (HCO3)
• Excessive H+ loss (e.g. vomiting, renal loss)
• Excess aldosterone (e.g. dehydration)
• Cushing’s/Conn’s syndrome

Question 25

Why is CO2 normal/high in metabolic acidosis?

Answer 25

Compensation by lungs –>decreased ventilation in an attempt to increase CO2