Primary FRCA Course Acid Base Physiology Exam Prep Questions Flashcards
The mechanisms of respiratory system control:
A low PO2 in the blood directly stimulates medullary chemoreceptors
False.
The mechanisms of respiratory system control:
CO2 in the blood directly stimulates medullary chemoreceptors
False. Medullary chemoreceptors respond directly to CSF pH rather than CO2. However, CSF pH does change rapidly in response to CO2, which readily crosses the blood brain barrier and there is then minimal buffering in CSF.
The mechanisms of respiratory system control:
H+ ions the blood directly stimulate medullary chemoreceptors
False. H+ ions the blood cannot cross the blood brain barrier, but stimulate respiration via peripheral chemoreceptors.
The mechanisms of respiratory system control:
H+ ions the blood directly stimulate carotid body chemoreceptors
True.
Regarding acid-base balance in the body:
A pH of 7.0 equates to a hydrogen ion concentration of 100 nmol/L
True. A pH of 7.0 indicates a hydrogen ion concentration of 10-7 mol/L or 100 nmol/L.
The mechanisms of respiratory system control:
The baroreceptor response to hypotension includes respiratory stimulation
True. In addition to the cardiovascular changes seen in response to the baroreceptor reflex, there is an increase in respiratory rate.
Regarding acid-base balance in the body:
pH is defined as the negative Loge of the hydrogen ion concentration in mol/L
False. pH calculation uses Log10 and not Log e.
Regarding acid-base balance in the body:
Albumin is an important intracellular buffer
False. Albumin is an extracellular buffer.
Regarding acid-base balance in the body:
Carbonic anhydrase catalyses the reaction between water and CO2
True. Carbonic anhydrase, present at many sites throughout the body, is essential for the reaction between water and CO2 to occur rapidly.
Regarding acid-base balance in the body:
Alkalosis lowers the free ionized calcium concentration
True. Alkalosis, e.g. from hyperventilation, encourages free Ca2+ ions to bind to proteins, and can lead to tetany.
The following represent typical oxygen content values that would be expected from each of these sites:
Renal vein - 125 mL/L
False. Google search indicates much lower than this.
The following represent typical oxygen content values that would be expected from each of these sites:
Coronary sinus - 90 mL/L
True.
The following represent typical oxygen content values that would be expected from each of these sites:
Radial artery - 200 mL/L
True.
The following represent typical oxygen content values that would be expected from each of these sites:
Umbilical vein - 130 mL/L
True.
The following represent typical oxygen content values that would be expected from each of these sites:
Pulmonary artery - 150 mL/L
True.
The following values would be compatible with a healthy person having lived at 5,000 m for 7 days:
[HCO3-] of 31 mmol/L
False. At 5,000 m the atmospheric pressure is approximately half that at sea level, which would produced a maximum PaO2 of around 5-6 kPa. This stimulates hyperventilation, lowering the PaCO2, and by day 7 there will have been metabolic compensation by excreting (rather than retaining) bicarbonate. A modest tachycardia would still be present and an increase in 2, 3 DPG moves the Hb-O2 dissociation curve to the right.
The following values would be compatible with a healthy person having lived at 5,000 m for 7 days:
PaO2 of 10.6 kPa
False. At 5,000 m the atmospheric pressure is approximately half that at sea level, which would produced a maximum PaO2 of around 5-6 kPa. This stimulates hyperventilation, lowering the PaCO2, and by day 7 there will have been metabolic compensation by excreting (rather than retaining) bicarbonate. A modest tachycardia would still be present and an increase in 2, 3 DPG moves the Hb-O2 dissociation curve to the right.
The following values would be compatible with a healthy person having lived at 5,000 m for 7 days:
PaCO2 of 3.9 kPa
True. At 5,000 m the atmospheric pressure is approximately half that at sea level, which would produced a maximum PaO2 of around 5-6 kPa. This stimulates hyperventilation, lowering the PaCO2, and by day 7 there will have been metabolic compensation by excreting (rather than retaining) bicarbonate. A modest tachycardia would still be present and an increase in 2, 3 DPG moves the Hb-O2 dissociation curve to the right.
The following values would be compatible with a healthy person having lived at 5,000 m for 7 days:
Resting heart rate of 95/min
True. At 5,000 m the atmospheric pressure is approximately half that at sea level, which would produced a maximum PaO2 of around 5-6 kPa. This stimulates hyperventilation, lowering the PaCO2, and by day 7 there will have been metabolic compensation by excreting (rather than retaining) bicarbonate. A modest tachycardia would still be present and an increase in 2, 3 DPG moves the Hb-O2 dissociation curve to the right.
The following values would be compatible with a healthy person having lived at 5,000 m for 7 days:
Right shift of Hb-O2 dissociation curve
True. At 5,000 m the atmospheric pressure is approximately half that at sea level, which would produced a maximum PaO2 of around 5-6 kPa. This stimulates hyperventilation, lowering the PaCO2, and by day 7 there will have been metabolic compensation by excreting (rather than retaining) bicarbonate. A modest tachycardia would still be present and an increase in 2, 3 DPG moves the Hb-O2 dissociation curve to the right.
Sodium 142 mmol/L. Potassium 4.7 mmol/L. Chloride 108 mmol/L. Bicarbonate 12 mmol/L. The above values for plasma concentrations would be compatible with:
A normal anion gap
False. These values show a metabolic acidosis with a raised anion gap (27), indicating an organic acid cause for the disturbance, such as DKA.
Sodium 142 mmol/L. Potassium 4.7 mmol/L. Chloride 108 mmol/L. Bicarbonate 12 mmol/L. The above values for plasma concentrations would be compatible with:
Stage 4 chronic kidney disease
False. These values show a metabolic acidosis with a raised anion gap (27), indicating an organic acid cause for the disturbance, such as DKA. There would a normal anion gap with CKD.
Sodium 142 mmol/L. Potassium 4.7 mmol/L. Chloride 108 mmol/L. Bicarbonate 12 mmol/L. The above values for plasma concentrations would be compatible with:
Diabetic ketoacidosis
True. These values show a metabolic acidosis with a raised anion gap (27), indicating an organic acid cause for the disturbance, such as DKA.
Sodium 142 mmol/L. Potassium 4.7 mmol/L. Chloride 108 mmol/L. Bicarbonate 12 mmol/L. The above values for plasma concentrations would be compatible with:
Hypoalbuminaemia
False. These values show a metabolic acidosis with a raised anion gap (27), indicating an organic acid cause for the disturbance, such as DKA. A low albumin reduces the anion gap as it is one of the main unmeasured anions.
Sodium 142 mmol/L. Potassium 4.7 mmol/L. Chloride 108 mmol/L. Bicarbonate 12 mmol/L. The above values for plasma concentrations would be compatible with:
Pyloric stenosis
False. These values show a metabolic acidosis with a raised anion gap (27), indicating an organic acid cause for the disturbance, such as DKA. Pyloric stenosis produces a metabolic alkalosis (raised bicarbonate).
Which of the following are true about acid-base regulation?
The pKa of H2CO3 is 6.1 at 37 degrees Celcius
True. The pKa for the main dissociation pathway of H2CO3 at body temperature is 6.1.
Which of the following are true about acid-base regulation?
The majority of filtered HCO3- is reabsorbed in Loop of Henle
False. Almost all H2CO3 is reabsorbed in the PCT.
Which of the following are true about acid-base regulation?
Phosphate is an important extracellular buffer
False. Phosphate is one of the main intracellular buffers.
Which of the following are true about acid-base regulation?
The distal convoluted tubule determines the final urine pH
True. True. The intercalated cells in the DCT regulate the final urine pH, excreting or reabsorbing H+ ions in exchange for K+ as circumstances require.
Which of the following are true about acid-base regulation?
H+ ions are exchanged for K+ ions in the kidney
True. The intercalated cells in the DCT regulate the final urine pH, excreting or reabsorbing H+ ions in exchange for K+ as circumstances require.
With regard to oxygen binding:
Affinity for haemoglobin is higher than for methaemoglobin
True. Met-Hb is unable to bind oxygen.
With regard to oxygen binding:
Affinity for fetal haemoglobin is higher than for haemoglobin
True. The fetal Hb dissociation curve is to the left of that for Hb, so has a higher O2 affinity.
With regard to oxygen binding:
Affinity for myoglobin is higher than for haemoglobin
True. It has to be otherwise muscles would not take up oxygen from the blood into myoglobin.
With regard to oxygen binding:
Each molecule of myoglobin can bind up to 4 molecules of oxygen
False. Myoglobin is a single ferroprotein chain, and can bind only 1 molecule of oxygen; it has a very high affinity for oxygen, releasing it only at extremely low PO2 levels.
With regard to oxygen binding:
The normal P50 for Hb is approximately 5.3 kPa
False. The normal P50 for Hb is approximately 3.5 kPa.
The following are buffers in renal tubular fluid?
Albumin
False. Albumin should not be present in tubular fluid.
The following are buffers in renal tubular fluid?
Ammonia
True. Ammonia, bicarbonate and phosphate buffer hydrogen ions secreted into renal tubular fluid.
The following are buffers in renal tubular fluid?
Bicarbonate
True. Ammonia, bicarbonate and phosphate buffer hydrogen ions secreted into renal tubular fluid.
The following are buffers in renal tubular fluid?
Phosphate
True. Ammonia, bicarbonate and phosphate buffer hydrogen ions secreted into renal tubular fluid.
The following are buffers in renal tubular fluid?
Urea
False. Urea is not a buffer.