CRL Quiz 1 2006

1

Which of the following statements regarding inspiration is correct?


  At rest inspiration is an active process accounting for 20% of the total oxygen consumption.

  Work is required to inflate the lungs from residual volume (RV) to functional residual capacity.

  During inspiration pleural pressure is more negative at the lung bases than the apices in an erect individual.

  Vital capacity (VC) is the difference between total lung capacity (TLC) and RV.


A is incorrect because inspiration at rest uses much less oxygen (about 3%) B is incorrect because attainment of RV requires active expiration, whereas FRC is the position where there is no activation of the inspiratory or expiratory muscles. C is incorrect because interpleural pressure is always more negative at the apices when erect.

2

Which of the following regarding spirometry is correct?


  Spirometry measures the time course of the expiratory flow from TLC to RV.

  In a normal young adult the FEV1/VC is usually less than 80%.

  Airflow obstruction usually causes a fall in FEV1 and VC.

  A restrictive ventilatory defect is not the only cause of a reduced VC.


Spirometry measures the time course of the expiratory volume (not flow) from TLC to RV. FEV1/VC is >85% in young adults. Airflow obstruction causes a fall in FEV1 but VC is usually normal.

3

Which of the following statements concerning gas exchange across the alveolarcapillary membrane is NOT correct?


  Under normal conditions, diffusion does not limit gas exchange.

  Hypoxaemia due to low V/Q units improves with supplemental oxygen.

  Carbon dioxide diffuses more readily than oxygen because it is more soluble.

  Nitrogen is in the alveoli but does not cross the A-C membrane.


Nitrogen diffuses across the alveolar-capillary membrane in the same way as oxygen and carbon dioxide.

4

Which of the following statements concerning the pulmonary circulation is NOT correct?


  It receives the same cardiac output as the systemic circulation.

  Pressure remains relatively low with increased cardiac output.

  Regional blood flow is controlled by contraction of the pulmonary venules.

  There is a net flow of fluid from the pulmonary capillaries into the interstitial spaces.

  The pressure difference between pulmonary arterioles and pulmonary venules is low.


The pulmonary arterioles control regional flow.

5

Which of the following statements regarding hyaline membrane disease is correct?


  There is likely to be hypoxia and CO2 retention.

  There is likely to be a slowed respiratory rate.

  The fundamental defect is an excess of pulmonary surfactant.

  An increase in inhaled oxygen is the only therapy required.


In HMD a surfactant deficiency results in significant V/Q mismatch resulting in hypoxia and CO2 retention which triggers a rise in respiratory rate. Treatment is administration of both surfactant and oxygen.

6

Which one of the following statements regarding acute lung injury is NOT correct?


  Acute lung injury may be caused by toxins in the alveolar space or the capillary.

  Acute lung injury causes hypoxemia through ventilation/perfusion mismatch and/or shunt.

  Acute lung injury causes pulmonary oedema.

  Acute lung injury is relatively resistant to treatment with steroidal antiinflammatory drugs.

  Acute lung injury is caused by the accumulation of activated lymphocytes.

7

Which ONE of the following is NOT a feature of a TYPICAL thoracic vertebra?


  Articular facets on the vertebral body

  Articular facet on the transverse process

  Deep superior vertebral notch.

  Long and vertically orientated spinous process

8

Which ONE of the following statements regarding the lungs is INCORRECT?


  The medial surface of the right lung is grooved by venous structures

  The right main bronchus typically divides before entering the root of the right lung

  The pulmonary veins lie posterior to the other hilar structures

  Each lung may be divided into functionally distinct bronchopulmonary segments

9

Which ONE of the following statements regarding the intercostal neurovascular bundle is INCORRECT?


  It runs in the costal groove

  It runs along the inferior aspect of the intercostal space

  The posterior intercostal arteries arise from the descending thoracic aorta

  The posterior intercostals veins drain into the azygous system of veins

10

Which of the following statements regarding the structure of the lungs is NOT correct?


  The terminal bronchioles are the smallest airways without alveoli.

  The respiratory bronchioles make up part of the anatomic dead space.

  In adult lungs there are about 300 million alveoli.

  The alveolar-capillary membrane has a surface area of about 50-100m2 and a thickness of 0.5micron.


Incorrect because respiratory bronchioles have occasional alveoli budding from their walls and therefore form part of the respiratory zone (ie where gas exchange occurs)

11

In acute lung injury, the most significant cells contributing to the progressive inflammation are:


  Vascular endothelial cells.

  Alveolar epithelial cells.

  Neutrophils.

  Platelets.

  Monocytes.

12

Which of the following statements regarding the first heart sound is correct?


  It coincides with the beginning of systole.

  It is caused by closure of the outlet valves of the ventricles.

  It is caused by blood entering the ventricle at the beginning of diastole.

  It is not usually heard.

  It is heard when the atria contract forcing blood into the ventricles.


B is the cause of the 2nd heart sound. C is the cause of the 3rd heart sound. E is the cause of the 4th heart sound.

13

Which of the following statements regarding the cardiac cycle is correct?


  Isovolumic contraction begins when the aortic valve opens.

  At the end of diastole left ventricular pressure is normally 25-30 mmHg.

  Ventricular pressure does not change during diastole.

  Isovolumic relaxation ends when the mitral valve opens.

  Left atrial pressure is always lower than left ventricular pressure.

14

Which of the following statements regarding drugs used to treat asthma is correct?


  Inhaled beclamethasone provides rapid reversal of bronchoconstriction.

  Iprotropium is the treatment of choice in mild asthma.

  Salbutamol has a longer duration of activity than formoterol.

  Salbutamol and formoterol are both α²-adrenoceptor agonists that increase cAMP in bronchial smooth muscle.

  Montelukast is a leukotriene receptor agonist.

15

With regard to an anterior chest radiograph, which of the following statements is correct?


  The optimum patient position is supine

  The branches of the aortic arch can be readily differentiated

  The normal horizontal fissure can be visualised

  The superior mediastinum is defined as being above the level of the pulmonary hila

  The normal cardiothoracic ratio (i.e. ratio of maximum transverse cardiac to thoracic cavity widths) in an adult is > 50%


A is incorrect. The optimum patient position is erect. B is incorrect. The branches of the aortic arch cannot be readily differentiated. D is incorrect. The superior mediastinum is defined as being above a plane between the MSJ and T 4/5 disc which corresponds with the bifurcation of the trachea and therefore lies above the pulmonary hila. E is incorrect. The normal cardiothoracic ratio is less than or equal to 50%