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Question 1
Correct
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A 55-year-old woman with a known history of bronchiectasis has lung function testing carried out and is found to have significant airways obstruction.Which of the following lung volumes or capacities is LEAST likely to be decreased in this case? Select ONE answer only.
Your Answer: Functional residual capacity
Explanation:Obstructive lung disorders are characterised by airway obstruction. Many obstructive diseases of the lung result from narrowing of the smaller bronchi and larger bronchioles, often because of excessive contraction of the smooth muscle itself.In obstructive lung disease, FEV1is reduced to <80% of normal and FVC is usually reduced but to a lesser extent than FEV1. The FEV1/FVC ratio is reduced to 80% in the presence of symptomsModerate airflow obstruction = FEV1of 50-79%Severe airflow obstruction = FEV1of 30-49%Very severe airflow obstruction = FEV1<30%.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 2
Correct
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The following statements concerning lung compliance is true EXCEPT?
Your Answer: Lung compliance is described by the equation: C = ∆ P/ ∆V, where C = compliance, P = pressure, and V = volume
Explanation:Lung compliance is the change in volume per unit change in distending pressure. It is calculated using the equation:Lung compliance = ΔV / ΔPWhere:ΔV is the change in volumeΔP is the change in pleural pressure.Lung compliance is inversely proportional to stiffness and elastance. It comprises static (no airflow) and dynamic (during continuous breathing) components. It is the slope of the pressure-volume curve.Lung compliance describes the distensibility of the lungs and the chest wall.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 3
Correct
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When the pulmonary artery is completely blocked, what is the ventilation over perfusion ratio for the area that it supplies?
Your Answer: Infinity
Explanation:The ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching ventilation and perfusion. A pulmonary artery carries deoxygenated blood from the right side of the heart to the lungs. When a large pulmonary embolus completed blocked a pulmonary artery the alveoli were ventilated but not perfused at all, then the V/Q ratio would be infinity.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 4
Correct
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The juxtacapillary receptors, or J receptors, are sensory cells that play an important role in the control of respiration.At which of the following anatomical sites are the J receptors located? Select ONE answer only.
Your Answer: The alveolar walls
Explanation:Juxtacapillary receptors (J receptors) are sensory cells that are located within the alveolar walls in juxtaposition to the pulmonary capillaries of the lung.The J receptors are innervated by the vagus nerve and are activated by physical engorgement of the pulmonary capillaries or increased pulmonary interstitial volume, for example, in the presence of pulmonary oedema, pulmonary embolus, pneumonia and barotraumas. They may also be stimulated by hyperinflation of the lung.Stimulation of the J receptors causes a reflex increase in breathing rate and is also thought to be involved in the sensation of dyspnoea. The reflex response that is produced is apnoea, followed by rapid breathing, bradycardia, and hypotension.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 5
Correct
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An arterial blood gas test is performed to a 25-year-old students who presents with confusion, headache, nausea and malaise. The results show that carbon monoxide levels are significantly high. Which of the following carbon monoxide poisoning assertions is true?
Your Answer: The PO 2 of the blood in CO poisoning can be normal
Explanation:By combining with haemoglobin to form carboxyhaemoglobin, carbon monoxide (CO) disrupts the blood’s oxygen transport function. CO binds to haemoglobin with a 240-fold higher affinity than oxygen. As a result, even small amounts of CO can bind a large portion of the blood’s haemoglobin, making it unavailable for oxygen transport. During a suspected carbon monoxide poisoning, the blood PO2 and haemoglobin concentrations will be normal, but the oxygen concentration will be drastically reduced. The oxygen dissociation curve will also shift to the left in the presence of Carboxyhaemoglobin ( haemoglobin and carbon monoxide combination), interfering with oxygen unloading.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 6
Correct
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The ventilation over perfusion ratio is highest at the apex of the lung. What is the approximate V/Q ratio at this area?
Your Answer: 3.3
Explanation:The ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching ventilation and perfusion. The ideal V/Q ratio is 1.Any mismatch between ventilation and perfusion will be evident in the V/Q ratio. If perfusion is normal but ventilation is reduced, the V/Q ratio will be less than 1, whereas if ventilation is normal, but perfusion is reduced, the V/Q ratio will be greater than 1. If the alveoli were ventilated but not perfused at all, then the V/Q ratio would be infinity. The V/Q ratio is also affected by location. The various areas of the lungs have a different V/Q ratio since ventilation and perfusion increase from the apex to the base of the lungs. The apex of the lungs has a V/Q ratio of approximately 3.3.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 7
Correct
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Low levels of which of the following arterial blood gas parameters stimulate the peripheral chemoreceptors?
Your Answer: Arterial pO 2
Explanation:Chemoreceptors are activated when the chemical composition of their immediate surroundings changes. Peripheral chemoreceptors, together with central chemoreceptors, regulate respiratory functions. They detect changes in arterial blood oxygen levels. Decreased arterial Po2 (partial pressure of oxygen) reflexly stimulates peripheral chemoreceptors. When peripheral chemoreceptors detect changes in arterial blood oxygen, they will trigger cardiorespiratory changes such as an increase in breathing and blood pressure. These reflexes are important for maintaining homeostasis during hypoxemia.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 8
Correct
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The transport of oxygen from maternal to fetal circulation is made possible by fetal haemoglobin. Which of the statements about fetal haemoglobin (HbF) is also correct?
Your Answer: The oxygen dissociation curve for foetal haemoglobin is shifted to the left of that of adult haemoglobin
Explanation:Fetal haemoglobin is the most common type of haemoglobin found in the foetus during pregnancy. It transports oxygen from the maternal circulation to the fetal circulation. It can easily bind to oxygen from the maternal circulation because it has a high affinity for oxygen. From 10 to 12 weeks of pregnancy to the first six months after birth, the erythroid precursor cells produce fetal haemoglobin. In comparison to adult haemoglobin, fetal haemoglobin has two alpha and two gamma subunits, whereas adult haemoglobin has two alpha and two beta subunits in its major form. And, unlike adult haemoglobin, the oxygen dissociation curve of fetal haemoglobin is left-shifted. Myoglobin is an oxygen storage molecule with a very high affinity for oxygen. Only when the partial pressure of oxygen is exceeded does it release oxygen.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 9
Correct
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A 17-year-old male patient diagnosed with cystic fibrosis is experiencing shortness of breath, coughing, and flu-like symptoms. His X-ray results shows atelectasis, or collapsed lung, specifically in his lower right lung. All of the following statements are true regarding collapsed lungs, except for which one.
Your Answer: Atelectasis is an example of a perfusion defect
Explanation:Atelectasis is a complete or partial collapse of the lung. It occurs when the alveoli deflate or are filled with alveolar fluid. It is considered a ventilation defect of the alveoli due to cystic fibrosis. It is not a perfusion defect. A perfusion defect will produce pathological dead space in which the lung alveoli are ventilated adequately but are not perfused, and there is no gas exchange. While with atelectasis, the alveoli remain perfused. However, there is impaired oxygen delivery and intrapulmonary shunting of blood will be present in the collapsed area. Since there is no exchange of gas at the capillary-alveolar interface of the collapsed segments, the pulmonary capillary blood will have similar PO2 and PCO2.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 10
Correct
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A patient with a history of worsening chronic breathlessness on exertion undergoes lung function testing. The results demonstrate an FEV 1 that is 58% predicted and an FEV 1 /FVC ratio less than 0.7.Which of the following is the most likely diagnosis? Select ONE answer only.
Your Answer: COPD
Explanation:Obstructive lung disorders are characterised by airway obstruction. Many obstructive diseases of the lung result from narrowing of the smaller bronchi and larger bronchioles, often because of excessive contraction of the smooth muscle itself.In obstructive lung disease, FEV1is reduced to <80% of normal and FVC is usually reduced but to a lesser extent than FEV1. The FEV1/FVC ratio is reduced to <0.7.Types of obstructive lung disorders include:Chronic obstructive pulmonary disease (COPD)AsthmaBronchiectasis
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 11
Correct
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Which one of these equations best defines lung compliance?
Your Answer: Change in volume / change in pressure
Explanation:Lung compliance is defined as change in volume per unit change in distending pressure. Lung compliance is calculated using the equation:Lung compliance = ΔV / ΔPWhere:ΔV is the change in volumeΔP is the change in pleural pressure.Static compliance is lung compliance in periods without gas flow, and is calculated using the equation:Static compliance = VT / Pplat − PEEPWhere:VT = tidal volumePplat = plateau pressurePEEP = positive end-expiratory pressure
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 12
Correct
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Pre-oxygenation is done prior to intubation to extend the ‘safe apnoea time’.Which lung volume or capacity is the most important store of oxygen in the body?
Your Answer: Functional residual capacity
Explanation:The administration of oxygen to a patient before intubation is called pre-oxygenation and it helps extend the ‘safe apnoea time’. The Functional residual capacity (FRC) is the volume of gas that remains in the lungs after normal tidal expiration. It is the most important store of oxygen in the body. The aim of pre-oxygenation is to replace the nitrogen in the FRC with oxygen. Apnoea can be tolerated for longer periods before critical hypoxia develops if the FRC is large. Patients with reduced FRC reach critical hypoxia more rapidly.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 13
Correct
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A 60-year-old man presents with marked breathlessness. He has with a history of ischaemic heart disease. On examination, there is coarse bibasal crackles, marked peripheral oedema and chest X-ray taken is consistent with severe pulmonary oedema. RR is 28 per minute. Which receptor is responsible for detecting pulmonary oedema and the subsequent increase in respiratory rate?
Your Answer: Juxtacapillary receptors
Explanation:Pulmonary oedema causes stimulation of the Juxtacapillary receptors (J receptors) leading to a reflex increase in breathing rate. These receptors are also thought to be involved in the sensation of dyspnoea. The J receptors are sensory cells and are located within the alveolar walls in juxtaposition to the pulmonary capillaries.Aortic baroreceptor are involved in detecting blood pressureCentral chemoreceptors detect changes in CO2 and hydrogen ion within the brainAtrial volume receptors regulate plasma volume
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 14
Correct
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A 64-year-old woman with a history of chronic breathlessness is referred for lung function testing.Which of the following statements regarding lung function testing is FALSE? Select ONE answer only.
Your Answer: In restrictive lung disease, the FVC is increased
Explanation:In restrictive lung disorders there is a reduction in the forced vital capacity (FVC) and the forced expiratory volume in one second (FEV1). The decline in the FVC is greater than that of the FEV1, resulting in preservation of the FEV1/FVC ratio (>0.7%).In obstructive lung disease, FEV1is reduced to <80% of normal and FVC is usually reduced but to a lesser extent than FEV1. The FEV1/FVC ratio is reduced to 80% in the presence of symptomsModerate airflow obstruction = FEV1 of 50-79%Severe airflow obstruction = FEV1 of 30-49%Very severe airflow obstruction = FEV1<30%.Spirometry is a poor predictor of durability and quality of life in COPD but can be used as part of the assessment of severity.COPD can only be diagnosed on spirometry if the FEV1 is <80% and FEV1/FVC ratio is < 0.7.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 15
Incorrect
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A 67-year-old man with chronic breathlessness is sent for a lung function test.Which statement concerning lung function testing is true?
Your Answer: In obstructive lung disease, FVC is usually increased
Correct Answer: In restrictive lung disease, the FEV 1 /FVC ratio is usually >0.7
Explanation:In restrictive lung disease, the FEV1/FVC ratio is usually >0.7%.In obstructive lung disease, FEV1 is reduced to <80% of normal and FVC is usually reduced. The FEV1/FVC ratio is reduced to 80% in the presence of symptomsModerate airflow obstruction = FEV 1 of 50-79%Severe airflow obstruction = FEV 1 of 30-49%Very severe airflow obstruction = FEV1<30%.Spirometry is a poor predictor of quality of life in COPD. However, it can be used as part of the assessment of severity of COPD.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 16
Correct
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A 19-year-old with a longstanding history of asthma presents to the ED with worsening symptoms of cough and wheeze and a peak expiratory flow rate (PEFR) measurement is taken.Which statement concerning PEFR is true?
Your Answer: PEFR is dependent upon the patient's height
Explanation:The maximum flow rate generated during a forceful exhalation, after maximal inspiration is the peak expiratory flow rate (PEFR).PEFR is dependent upon initial lung volume. It is, therefore, dependant on patient’s age, sex and height.PEFR is dependent on voluntary effort and muscular strength of the patient.PEFR is decreased with increasing airway resistance, e.g. in asthma, and it correlates well with the forced expiratory volume in one second (FEV1) value measured in spirometry. This correlation decreases in patients with asthma as airflow decreases.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 17
Correct
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When calculating the ventilation over perfusion ratio of a male patient, you should remember the ideal V/Q ratio for this patient to compare with his results. What is the approximate ventilation value for a healthy male patient?
Your Answer: 5 L/min
Explanation:The ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the matching ventilation and perfusion. The ideal V/Q ratio is 1. In an average healthy male, the ventilation value is approximately 5 L/min and the perfusion value is approximately 5 L/min. Any mismatch between ventilation and perfusion will be evident in the V/Q ratio. If perfusion is normal but ventilation is reduced, the V/Q ratio will be less than 1, whereas if ventilation is normal but perfusion is reduced, the V/Q ratio will be greater than 1. If the alveoli were ventilated but not perfused at all, then the V/Q ratio would be infinity.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 18
Correct
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A lung function test is being performed on a male patient. For this patient, which of the following volumes for functional residual capacity is considered a normal result?
Your Answer: 2.0 L
Explanation:The volume of air that remains in the lungs after a single breath is known as functional residual capacity (FRC). It is calculated by combining the expiratory reserve volume and residual volume. In a 70 kg, average-sized male, a normal functional residual capacity is approximately 2100 mL.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 19
Correct
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What is the partial pressure of oxygen if it makes up 20.9 percent of the ambient air composition and the atmospheric pressure of ambient air is 760 mmHg?
Your Answer: 159 mmHg
Explanation:Ambient air is atmospheric air in its natural state. Ambient air is typically 78.6% nitrogen and 20.9% oxygen. The extra 1% is made up of carbon, helium, methane, argon and hydrogen. The partial pressure of any gas can be calculated using this formula: P = atmospheric pressure (760 mmHg) x percent content in the mixture. Atmospheric pressure is the sum of all of the partial pressures of the atmospheric gases added together: The formula for atmospheric pressure is: Patm = PN2 + PO2 + PH2O + PCO2. The atmospheric pressure is known to be 760 mmHg. The partial pressures of the various gases can be estimated to have partial pressures of approximately 597.4 mmHg for nitrogen, 158.8 mm Hg for oxygen, and 7.6 mmHg for argon.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 20
Correct
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A 58-year-old patient presents with sputum production and worsening exertional breathlessness. A spirometry is done and his results leads to a diagnosis of obstructive lung disease with mild airflow obstruction.What FEV1 value would correspond with mild airflow obstruction according to the NICE guidelines?
Your Answer: FEV 1 >80%
Explanation:Airflow obstruction according to the latest NICE guidelines, is defined as: Mild airflow obstruction = an FEV 1 of >80% in the presence of symptoms Moderate airflow obstruction = FEV 1 of 50-79% Severe airflow obstruction = FEV 1 of 30-49% Very severe airflow obstruction = FEV1<30%.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 21
Incorrect
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A CT pulmonary angiography of a patient with a massive pulmonary embolus will most likely show which of the following signs?
Your Answer: Decreased alveolar dead space
Correct Answer: Increased alveolar dead space
Explanation:A CT pulmonary angiogram is an angiogram of the blood vessels of the lungs. It is a diagnostic imaging test used to check for pulmonary embolism. A pulmonary embolism is caused by a blood clot or thrombus that has become lodged in an artery in the lung and blocks blood flow to the lung. A patient with pulmonary embolism may feel an abrupt onset of pleuritic chest pain, shortness of breath, and hypoxia. Also, pulmonary embolism can result in alveolar dead space. Dead space represents the volume of ventilated air that does not participate in gas exchange. The alveolar dead space is caused by ventilation/perfusion imbalances in the alveoli. It is defined as the sum of the volumes of alveoli that are ventilated but not perfused. Aside from pulmonary embolism, smoking, bronchitis, emphysema, and asthma are among the other causes of alveolar dead space. The other types of dead space are the following: Anatomical dead space is the portion of the airways that conducts gas to the alveoli. This is usually around 150 mL, and there is no possibility of gas exchange in these areas. Physiological dead space is the sum of anatomical and alveolar dead spaces. Physiological dead space can account for up to 30% of the tidal volume.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 22
Incorrect
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You're evaluating a male patient who's having a lung function test done. In calculating the patient’s functional residual capacity, what parameters should you add to derive the functional residual capacity volume?
Your Answer: Residual volume + tidal volume
Correct Answer: Expiratory reserve volume + residual volume
Explanation:The volume of air that remains in the lungs after a single breath is known as functional residual capacity (FRC). It is calculated by combining the expiratory reserve volume and residual volume.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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Question 23
Correct
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A patient is referred for lung function tests on account of a history of breathlessness and cough.Which statement about lung volumes is correct?
Your Answer: The tidal volume is the volume of air drawn in and out of the lungs during normal breathing
Explanation:The tidal volume(TV) is the amount of air that moves in and out of the lungs with each respiratory cycle. In a healthy male, the usual volume is 0.5 L (,7 ml/kg body mass).The vital capacity(VC) is the maximum amount of air that can be exhaled following maximal inspiration. The usual volume in a healthy male is 4.5 L.The residual volume(RV) is the amount of air remaining in the lungs after maximum expiration. The usual volume in a healthy male is 1.0 L.The inspiratory reserve volume(IRV) is the maximum amount of air that can be breathed in forcibly after normal inspiration. The usual volume in a healthy male is 3.0 L.The expiratory reserve volume(ERV) is the volume of air that can be breathed out forcibly after normal expiration. The usual volume in a healthy male is 1.0 L.Total lung capacity(TLC) is the volume of air the lungs can accommodate. TLC = RV+VC. The usual volume in a healthy male is 5.5 L.
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This question is part of the following fields:
- Physiology
- Respiratory Physiology
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SESSION STATS - PERFORMANCE PER SPECIALTY
