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 Log e 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. 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.
Carbon dioxide:
Is 5 times more soluble in plasma than oxygen
False. CO2 is 25 times more soluble than oxygen.
Carbon dioxide:
Content in venous blood is approximately 500 mL/L
True. 90% of it is carried as bicarbonate, with a content of 510 mL/L in venous blood.
Carbon dioxide:
Is carried in blood largely as bicarbonate
True.
Carbon dioxide:
Conversion to carbamino compounds requires carbonic anhydrase
False. Carbamino compound formation is rapid and does not require enzyme activity.
Carbon dioxide:
Content in blood increases as Hb unloads oxygen
True. This is the Haldane effect.
The following would be expected at the peak of vigorous exercise:
Oxygen consumption increased 10 fold
True. Maximum O2 consumption increases approximately 10 fold during vigorous exercise.
The following would be expected at the peak of vigorous exercise:
Overall oxygen extraction ratio increased to 0.75
False. Maximum O2 consumption increases approximately 10 fold during vigorous exercise, and this is met by an increase in cardiac output of 5 times, minute ventilation 10 times and a doubling of the oxygen extraction ratio to 0.5.
The following would be expected at the peak of vigorous exercise:
Coronary oxygen extraction ratio doubled
False. Maximum O2 consumption increases approximately 10 fold during vigorous exercise, and this is met by an increase in cardiac output of 5 times, minute ventilation 10 times and a doubling of the oxygen extraction ratio to 0.5. The heart already has a high extraction ratio and must meet increased demand by increasing coronary flow.
The following would be expected at the peak of vigorous exercise:
Cardiac output increased 10 fold
False. Maximum O2 consumption increases approximately 10 fold during vigorous exercise, and this is met by an increase in cardiac output of 5 times, minute ventilation 10 times and a doubling of the oxygen extraction ratio to 0.5. The heart already has a high extraction ratio and must meet increased demand by increasing coronary flow.
The following would be expected at the peak of vigorous exercise:
Minute ventilation increased 10 fold
True. Maximum O2 consumption increases approximately 10 fold during vigorous exercise, and this is met by an increase in cardiac output of 5 times, minute ventilation 10 times and a doubling of the oxygen extraction ratio to 0.5. The heart already has a high extraction ratio and must meet increased demand by increasing coronary flow.
Acutely reducing the inspired oxygen concentration to 10% at sea level will cause:
Increased urinary pH
True. Hyperventilation will cause a respiratory alkalosis and consequently the urinary pH will increase in attempt to correct this.
Acutely reducing the inspired oxygen concentration to 10% at sea level will cause:
Increased cardiac output
True. Mild degrees of hypoxia will cause sympathetic stimulation with a consequent increase in heart rate and cardiac output.
Acutely reducing the inspired oxygen concentration to 10% at sea level will cause:
Increased capacity of Hb for oxygen
True. Alkalosis causes increased affinity of Hb for oxygen due to the shift of the oxygen-haemoglobin dissociation curve in the lungs.
Acutely reducing the inspired oxygen concentration to 10% at sea level will cause:
A respiratory acidosis
False. Hyperventilation will cause a respiratory alkalosis.
Acutely reducing the inspired oxygen concentration to 10% at sea level will cause:
Increased erythropoietin secretion
True. Erythropoietin is secreted in response to hypoxia but its effect is not seen acutely.
Haemoglobin:
Contains 2 alpha chains
True. Haemoglobin is a molecule comprised of four polypeptide chains, 2 alpha and 2 beta.
Haemoglobin:
Carries 4 molecules of oxygen per chain
False. Each haemoglobin molecule carries 4 molecules of oxygen.
Haemoglobin:
Is a 4-chain structure
True.
Haemoglobin:
Contains a ferrous ion
True. Each polypeptide chain contains a porphyrin ring with a ferrous ion at its centre.
Haemoglobin:
Is a polypeptide
True.
The oxygen content of blood is decreased in:
COHb
True. The oxygen content of blood is calculated by adding together the amount of oxygen carried by haemoglobin and the amount of oxygen carried in solution. In states of anaemia the former is reduced, as it is in methaemoglobinaemia and in the presence of carboxyhaemoglobin. Dissolved oxygen only represents about 1% of the total and is a function of PO2. It therefore increases under hyperbaric conditions.
The oxygen content of blood is decreased in:
Methaemoglobinaemia
True. The oxygen content of blood is calculated by adding together the amount of oxygen carried by haemoglobin and the amount of oxygen carried in solution. In states of anaemia the former is reduced, as it is in methaemoglobinaemia and in the precence of carboxyhaemoglobin. Dissolved oxygen only represents about 1% of the total and is a function of PO2. It therefore increases under hyperbaric conditions.
The oxygen content of blood is decreased in:
Anaemia
True. The oxygen content of blood is calculated by adding together the amount of oxygen carried by haemoglobin and the amount of oxygen carried in solution. In states of anaemia the former is reduced, as it is in methaemoglobinaemia and in the precence of carboxyhaemoglobin. Dissolved oxygen only represents about 1% of the total and is a function of PO2. It therefore increases under hyperbaric conditions.
The oxygen content of blood is decreased in:
Chronic renal failure
True. The oxygen content of blood is calculated by adding together the amount of oxygen carried by haemoglobin and the amount of oxygen carried in solution. In states of anaemia the former is reduced, as it is in methaemoglobinaemia and in the precence of carboxyhaemoglobin. Dissolved oxygen only represents about 1% of the total and is a function of PO2. It therefore increases under hyperbaric conditions.
The oxygen content of blood is decreased in:
Hyperbaric conditions
False. The oxygen content of blood is calculated by adding together the amount of oxygen carried by haemoglobin and the amount of oxygen carried in solution. In states of anaemia the former is reduced, as it is in methaemoglobinaemia and in the precence of carboxyhaemoglobin. Dissolved oxygen only represents about 1% of the total and is a function of PO2. It therefore increases under hyperbaric conditions.
The oxygen-haemoglobin dissociation curve moves to the right:
With an increase in temperature
True. Factors causing a right shift are: Hyperthermia, decreased pH, increased 2,3,DPG, increased PaCO2, pregnancy, haemoglobin S and after altitude acclimatisation.
The oxygen-haemoglobin dissociation curve moves to the right:
When 2,3-DPG levels increase
True. Factors causing a right shift are: Hyperthermia, decreased pH, increased 2,3,DPG, increased PaCO2, pregnancy, haemoglobin S and after altitude acclimatisation.
The oxygen-haemoglobin dissociation curve moves to the right:
When carbon dioxide concentration increases
True. Factors causing a right shift are: Hyperthermia, decreased pH, increased 2,3,DPG, increased PaCO2, pregnancy, haemoglobin S and after altitude acclimatisation.
The oxygen-haemoglobin dissociation curve moves to the right:
With an increase in hydrogen ion concentration
True. Factors causing a right shift are: Hyperthermia, decreased pH, increased 2,3,DPG, increased PaCO2, pregnancy, haemoglobin S and after altitude acclimatisation.
The oxygen-haemoglobin dissociation curve moves to the right:
On exercise
True. Factors causing a right shift are: Hyperthermia, decreased pH, increased 2,3,DPG, increased PaCO2, pregnancy, haemoglobin S and after altitude acclimatisation.
The oxyhaemoglobin dissociation curve is shifted to the left in:
Pregnancy
False. The P50 is higher in normal pregnancy, therefore it is a right shift.
The oxyhaemoglobin dissociation curve is shifted to the left in:
Stored blood
True. Due to lower 2,3 DPG levels.
Factors causing a left shift are: Hypothermia, increased pH, decreased 2,3,DP and decreased PaCO2. The curves for fetal, carboxyhaemoglobin and methaemoglobin are also shifted left.
The oxyhaemoglobin dissociation curve is shifted to the left in:
Fetal haemoglobin
True. Factors causing a left shift are: Hypothermia, increased pH, decreased 2,3,DP and decreased PaCO2. The curves for fetal, carboxyhaemoglobin and methaemoglobin are also shifted left.
The oxyhaemoglobin dissociation curve is shifted to the left in:
Cyanide poisoning
False. Cyanide poisoning causes histotoxic hypoxia which is the inability of cells to take up or use oxygen from the bloodstream, despite physiologically normal delivery of oxygen to such cells and tissues. It does not affect the oxyhaemoglobin dissociation curve.
The oxyhaemoglobin dissociation curve is shifted to the left in:
Carbon monoxide poisoning
True. Factors causing a left shift are: Hypothermia, increased pH, decreased 2,3,DP and decreased PaCO2. The curves for fetal, carboxyhaemoglobin and methaemoglobin are also shifted left.
The following drugs are bases:
Atracurium
True.
It is important to understand the ionization of drugs with changing pH (and hence membrane transfer). As a guide to identifying whether a drug is an acid or base, think of its salt when prepared:
Sodium-drug (or similar) = acid
Drug-sulphate (or similar) = base
Bases: Atracurium besylate, bupivacaine hydrochloride, Morphine sulphate
Acids: Sodium diclofenac, sodium thiopental
The following drugs are bases:
Bupivacaine
True.
It is important to understand the ionization of drugs with changing pH (and hence membrane transfer). As a guide to identifying whether a drug is an acid or base, think of its salt when prepared:
Sodium-drug (or similar) = acid
Drug-sulphate (or similar) = base
Bases: Atracurium besylate, bupivacaine hydrochloride, Morphine sulphate
Acids: Sodium diclofenac, sodium thiopental
The following drugs are bases:
Diclofenac
False.
It is important to understand the ionization of drugs with changing pH (and hence membrane transfer). As a guide to identifying whether a drug is an acid or base, think of its salt when prepared:
Sodium-drug (or similar) = acid
Drug-sulphate (or similar) = base
Bases: Atracurium besylate, bupivacaine hydrochloride, Morphine sulphate
Acids: Sodium diclofenac, sodium thiopental
The following drugs are bases:
Morphine
True.
It is important to understand the ionization of drugs with changing pH (and hence membrane transfer). As a guide to identifying whether a drug is an acid or base, think of its salt when prepared:
Sodium-drug (or similar) = acid
Drug-sulphate (or similar) = base
Bases: Atracurium besylate, bupivacaine hydrochloride, Morphine sulphate
Acids: Sodium diclofenac, sodium thiopental
The following drugs are bases:
Thiopental
False.
It is important to understand the ionization of drugs with changing pH (and hence membrane transfer). As a guide to identifying whether a drug is an acid or base, think of its salt when prepared:
Sodium-drug (or similar) = acid
Drug-sulphate (or similar) = base
Bases: Atracurium besylate, bupivacaine hydrochloride, Morphine sulphate
Acids: Sodium diclofenac, sodium thiopental
The following are normal for an adult at rest:
Anion gap of 12 mmol/L
True. The normal anion gap is 8-16 mmol/L.
The following are normal for an adult at rest:
Carbon dioxide production of 500mL/min
False. Carbon dioxide production is around 200 mL/min (with an RQ of 0.8).
The following are normal for an adult at rest:
Hydrogen ion concentration of 40 mmol/L
False. Hydrogen ion concentration is 40 nmol/L (not mmol).
The following are normal for an adult at rest:
Carboxy-Hb of 0.5%
True. Up to 2% of Hb can be bound to CO even in non-smokers.
The following are normal for an adult at rest:
Fetal-Hb of 0.5%
True. A small amount of HbF is still produced in adult life, the amount varying considerably, and can be as high as 5%.
The following would be compatible with a 10 day history of pyloric stenosis
Raised aldosterone level
True. Pyloric stenosis results in a loss of water, chloride and hydrogen ions and a rise in aldosterone secretion is part of the response to volume loss.
The following would be compatible with a 10 day history of pyloric stenosis
Serum Chloride of 86 mmol/L
True. Pyloric stenosis results in a loss of water, chloride and hydrogen ions and a rise in aldosterone secretion is part of the response to volume loss.
The following would be compatible with a 10 day history of pyloric stenosis
Serum Potassium of 5.5 mmol/L
False. In the DCT Hydrogen ions are retained in exchange for K+ excretion, and so hypokalaemia would be expected.
The following would be compatible with a 10 day history of pyloric stenosis
Arterial PCO2 of 5.9 kPa
True. Hypoventilation is a respiratory compensation for the metabolic alkalosis.
The following would be compatible with a 10 day history of pyloric stenosis
Arterial pH of 7.54
True. Pyloric stenosis results in a loss of water, chloride and hydrogen ions and a rise in aldosterone secretion is part of the response to volume loss.
The following are true about renal acid-base regulation:
Aldosterone is the main regulator of urinary pH
False. Aldosterone has no significant role in acid-base balance.
The following are true about renal acid-base regulation:
Filtered bicarbonate acts as a buffer in tubular fluid
True. Filtered bicarbonate is the main intraluminal buffer for secreted.
The following are true about renal acid-base regulation:
Hydrogen ions are secreted by the intercalated cells in the PCT
False. The intercalated cells are in the DCT.
The following are true about renal acid-base regulation:
Hydrogen ion secretion in the PCT is dependent on carbonic anhydrase
True. Hydrogen ions are secreted in the PCT, production of which requires the action of carbonic anhydrase.
The following are true about renal acid-base regulation:
The kidney excretes the body’s largest acid load
False. The largest acid load produced by the body is respiratory acid, in the form of carbon dioxide, and is excreted by the lungs.
The Haldane Effect:
Enhances carbon dioxide unloading in the lungs
True. The Haldane Effect improves Carbon dioxide uptake in the peripheries and unloading in the lungs and results mainly (70%) from the more rapid formation of carbamino compounds by deoxyhaemoglobin.
The Haldane Effect:
Is due mainly to enhanced formation/breakdown of carbamino compounds
True. The Haldane Effect improves Carbon dioxide uptake in the peripheries and unloading in the lungs and results mainly (70%) from the more rapid formation of carbamino compounds by deoxyhaemoglobin.
The Haldane Effect:
Is more effective in a patient breathing 100% Oxygen
False. Breathing 100% Oxygen will not have any influence.
The Haldane Effect:
Is related to the Hb-Oxygen interaction
True. The Haldane Effect improves Carbon dioxide uptake in the peripheries and unloading in the lungs and results mainly (70%) from the more rapid formation of carbamino compounds by deoxyhaemoglobin
The Haldane Effect:
Results directly in part from changes in 2,3 DPG
False. 2, 3 DPG has a direct action towards the Bohr but not the Haldane Effect
