CRL Quiz 1 2005

1

Which ONE of the following statements regarding the blood vessels is correct?


  The blood flow velocity is fastest in the capillaries.

  Small arteries are important determinants of total peripheral resistance.

  The large veins act as diastolic pumps.

  Blood in the pulmonary vein is deoxygenated.

  Arteries are more compliant than veins.


Small cross-secional area and muscular wall, improved regulator of organ perfusion and major contributors of resistance to blood flow.

2

Which ONE of the following statements regarding the heart is NOT CORRECT?


  The atrio-ventricular valves are closed during systole.

  If the atrio-ventricular valves (mitral & tricuspid) are open, then the ventricular outflow valves (aortic and pulmonary) must be closed.

  Increasing cardiac contractility will increase the ventricular ejection fraction.

  The ventricle empties during systole.

  The left ventricle has more distensible walls than the right ventricle.


The left ventricle has a more muscular wall than right ventricle and is therefore less distensible.

3

Which of the following statements about a typical neurovascular bundle of an intercostal space is/are correct? A. It lies between the internal and external intercostal muscles. B. It lies in the lower part of the intercostal space. C. It has no associated lymphatics. D. It consists of vein arter, nerve from above downwards.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.


A typical intercostal neurovascular bundle lies in the neurovascular plane between internal and innermost intercostals. it runs along the top of the space consists of (from above down) vein, artery and nerve with accompanying lymphatics.

4

Which of the following statements about the parietal pleura is/are correct? A. It is in contact with the outer surface of each lung. B. It is supplied by the visceral nerves. C. It does not extend above the level of the clavicles D. It lines the inner surface of the thoracic wall.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.


The parietal pleura lines the thoracic wall, mediastinum, suprapleural membrane and diaphragm. It receives somatic sensory supply.

5

Which ONE of the following is NOT a potential hazard or complication for the patient from a CT (computed tomography) scan of the chest?


  Carcinogenesis (development of cancer) from exposure to ionizing radiation.

  Acute blindness from exposure to ionizing radiation.

  Acute renal failure from the injuection of intravenous contrast.

  Fatal acute anaphylactic (allergic) reaction to intravenous contrast.

  Subcutaneous tissue injury from leakage of intravenous contrast during injection.


Acute blindeness from ionizing radiation requires over 100mSv of direct radiation, which does not occur in medical imaging even with multi-phasic dedicated CT of the head or face, and certainly not during CT scans of the chest.

6

Which ONE of the following statements regarding β2-adrenoceptor agonists is correct?


  Long-acting β2-adrenoceptor agonists have significant anti-inflammatory actions.

  Only long-acting β2-adrenoceptor agonists cause tachycardia and tremor.

  Long-acting β2-adrenoceptor agonists are administered as needed.

  Short-acting β2-adrenoceptor agonists oppose the actions of smooth muscle constrictor agents by decreasing activation of myosin light chain kinase.

  β2-adrenoceptor agonists are ineffective if administered orally.


β2-adrenoceptor agonists stimulate Gs leading to release of adenylate cyclase and an increase in cAMP activation and Protein Kinase A. PKA phosphorlyates calcium transports thereby decreasing cytoplasmic calcium levels and decreasing MLCK activation.

7

Woolcock described asthma s "the disease where the airways close too easily and too much". In functional terms, the dose of inhaled methacholine plotted against FEV1 in severe asthma would appear relative to health people, to


  Move leftward and upward.

  Have a clear plateua, but at a higher concentration of methacholine.

  Be identical but accompanied by sensation of breathlessness.

  Be easily corrected with inhaled β2-adrenoceptor agonists.

  Lack a clear plateau and move to the right.


The airways of asthmatic patients show an increase in sensitivity and maximum response to MCh which would lead toa shift of the dose-response curve to the left and upwards in comparison to normal individuals.

8

Which of the following are functions of the upper airway? A. Cough B. Swalling C. Defense of the lower respiratory system. D. Control of airflow in respiration.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.


Trachea, bronchi and bronchiols warm and humidify the air, distribute it to the gas exchange surface of lung and serve as part of the body defence system. The pharynx and larynx have an important role in swallowing.

9

In relation to the profile of airflow through a large proximal airway e.g. the trachea, which of the following statements is/are correct? A. Airflow is rubulent. B. Airflow is dependent on gas viscosity. C. Airflow is dependent on gas density. D. Airflow is laminar.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.


Turbulent flow occurs in the trachea and large bronchi. Laminar flow occurs mainly in the small peripheral airways where flow is slow. Turbulent flow is greatly affected by gas density.

10

Regarding the function of the respiratory system, which ONE of the following statements is correct?


  The respiratory system regulates body pH by excreting bicarbonate.

  Reduced PaO2 does nto necessarily result in reduced tissue oxygen delivery.

  The functional reserve of the lungs is small and humans become incapacitated by minor reduction in lung capacity or modest increases in demand.

  The respiratory system is poorly protected to withstand injury by inhaled and circulating triggers of inflammation.

  Breathlessness is a sensitive and specific symptom of dysfunction of the respiratory system.


When PaO2 is lowered there is capacity for tissue to extract a greater proportion of the oxygen carried from the Hb.

11

Which ONE of the following conditions would have the greatest adverse effect on total tissue oxygen supply?


  A decrease in PaO2 from 100 to 75mmHg.

  A decrease in SaO2 from 100 to 75%

  A decrease in Hb concentration from 15 to 10g/100mL.

  15% carboxyhaemoglobin (total Hb = 15g/100mL).

  A decrease in cardiac output from 5L/min to 4L/min.


Increasing carboxyhaemoglobin to 15% (normally 1-2%) would reduce effective Hb to approximately 12.5/100mL (higher than option 3) which would therefore have a lesser adverse effect. Increased extraction of O2 from Hb would help to compensate in the other situations.

12

The hilum of the lung does NOT contain which ONE of the following.


  Bronchus.

  Pulmonary artery.

  Lymph nodes.

  Internal thoracic artery.

  Pulmonary vein.


The internal thoracic artery runs down the inside of the anterior wall one finger's breadth from the lateral border of the sternum and supplies anterior intercostla arteries to the adjacent intercostal spaces. It doesn't traverse the hilum of the lung.

13

Which ONE of the following statements concerning pulmonary interstitial fibroblasts is NOT CORRECT?


  Pulmonary interstitial fibroblasts synthesise type 3 collagen and elastin.

  Pulmonary interstitial fibroblasts are contractile cells.

  Pulmonary interstitial fibroblasts communicate via gap junctions.

  Pulmonary interstitial fibroblasts migrate into the alveolar wall in response to cytokines released by activated macrophages.

  Pulmonary interstitial fibroblasts contain fat droplets.


Pulmonary interstitial fibroblasts or septal cells are mesenchymal cells that are similar to the stellate cells of the liver in that they have contractile properties, communicate via gap junctions and have fat droplets in their cytoplasm.
One of their major functions is the synthesis of type 3 colalgen and elastin in the alveolar wall. Although they respond to cytokines, they have no need to migrate into the alveolar wall because they reside there (in the interstitium).

14

Which ONE of the following statements regarding respiratory function is NOT CORRECT?


  Ventilation is greatest in the dependent part of the lungs.

  At functional residual capacity (FRC), outward chest recoil is balanced by inward lung elastic recoil.

  Airway closure at low lung volumes is a determinant of residual volume (RV).

  Closing volume is normally higher than FRC.

  Chest wall stiffness is a determinant of both residual volum (RV) and total lung capacity (TLC).


Closing volume is the lung volume at which the dependent airways begin to close. This does not occur at the end of normal expiration (FRC).

15

Which of the following statements regarding hyaline membrane disease is/are correct? A. There is likely to be hypoxia and CO2 retention. B. There is likely to be a slowed respiratory rate. C. The fundamental defect is a deficiency of pulmonary surfactant. D. An increase in inhaled oxygen is the only therapy required.


  If only A, B and C are correct.

  If only A and C are correct.

  If only B and D are correct.

  If only D is correct.

  If all are correct.


In HMD, the 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.