Biochemistry (Respiratory)

Question 1

What is the normal range of hydrogen ion concentration?

Answer 1

35-45 nanomol/L so regulation is very tight.

Question 2

What are some examples of H+ buffers in the body?

Answer 2

Haemoglobin, phosphate, bicarbonate and ammonium.

Question 3

Why is the bicarbonate buffer so important?

Answer 3

Other buffer systems reach equilibrium but carbonic acid is removed as CO2, so the only limit is the conc of HCO3-.

Question 4

What is the equilibrium equation for H+ and bicarbonate?

Answer 4

H+ + HCO3- H2CO3 CO2 + H2O

Question 5

What is the equation involving pCO2, H+ and HCO3-?

Answer 5

[H+]=pCO2/[HCO3-]

Question 6

What are the respiratory and metabolic components?

Answer 6

Respiratory: pCO2. Metabolic: HCO3-.

Question 7

What is an acidosis and an alkalosis?

Answer 7

Acidosis: increase in [H+], or a process tending to cause increases in [H+]. Alkalosis: opposite.

Question 8

What is an acidaemia and an alkalaemia?

Answer 8

Acidaemia is increase is [H+], alkalaemia is opposite.

Question 9

What is there too much of when there is a metabolic acidosis?

Answer 9

H+

Question 10

How is a metabolic acidosis corrected?

Answer 10

Bicarbonate equilibrium shifts to the right so they breathe off more CO2 (deep breathing).

Question 11

What happens to the bicarbonate concentration in a metabolic acidosis?

Answer 11

Decreases as it is reacting with the extra H+.

Question 12

What is the primary problem and the compensation in a metabolic acidosis?

Answer 12

Primary: too much H+, compensation: blow off more CO2.

Question 13

What is there too much of in a respiratory acidosis?

Answer 13

CO2.

Question 14

How is a respiratory acidosis corrected?

Answer 14

Bicarbonate equilibrium shifts to the left, more H+ excreted.

Question 15

What is the primary problem and the compensation in a respiratory acidosis?

Answer 15

Primary is too much CO2, compensation is excreting more H+.

Question 16

Describe how metabolic compensation for respiratory acidosis occurs in the kidneys.

Answer 16

CO2 from blood diffuses into renal tubular cells -> reacts with water so equilbrium shifts left -> H+ produced is then excreted into renal tubular lumen where it is buffered (lost from the body) -> bicarbonate goes into blood.

Question 17

What is there too little of in a metabolic alkalosis?

Answer 17

H+.

Question 18

How is a metabolic alkalosis corrected?

Answer 18

Equilibrium shifts left, to compensate you can hypoventilate (ability to do this is limited by hypoxia).

Question 19

What is there too little of in a respiratory alkalosis?

Answer 19

CO2.

Question 20

How is a respiratory alkalosis compensated?

Answer 20

Equilibrium shifts right, kidneys decrease bicarbonate reabsorption (more bicarbonate excreted, can take several days).

Question 21

What are some of the causes of respiratory acidosis?

Answer 21

Choking, bronchopneumonia (lung tissue filled with fluid), COPD (due to inability to ventilate).

Question 22

What are some causes of respiratory alkalosis?

Answer 22

Hysterical overbreathing, mechanical over-ventilation e.g. in intensive care units, raised intracranial pressure (stimulates respiratory centre).

Question 23

What are some causes of metabolic acidosis?

Answer 23

Impaired H+ secretion e.g. renal failure, increased H+ production of ingestion, loss of bicarbonate.

Question 24

What are some causes of metabolic alkalosis?

Answer 24

Loss of H+ in vomit (only with pyloric stenosis), alkali ingestion, potassium deficiency.

Question 25

What does it mean when you say you can’t overcompensate physiologically?

Answer 25

Someone with acidosis isn’t going to go too far in compensation to develop alkalosis.