CRL Quiz 1 Sample 1
Which one of the following statements regarding the pulmonary circulation is correct?
There is a small nett flow of fluid from the pulmonary capillary bed.
The pulmonary vessels are thin walled because they receive only a proportion of the cardiac output from the right ventricle.
Spasm of the capillaries diverts blood away from poorly ventilated area.
Giving supplemental oxygen improves the reduced Pao2 due to low V/Q units but it does not relieve the arteriolar spasm associated with these units.
Mean pulmonary artery pressure is about 50% of mean systemic arterial pressure.
The pulmonary vessels are relatively thin walled but they do receive all of the right ventricular output. The arterioles, not the capillaries contract in response to a regional reduction in Pa02. Improving a low Pa02 with supplemental O2 will relieve the arteriolar spasm. Mean pulmonary artery pressure is about 10% of mean systemic pressure.
Which one of the following statements about the pleura is incorrect?
The two pleural cavities do not connect.
During quiet respiration the lungs do not expand fully into the costodiaphragmatic and costophrenic recesses of the pleural cavity.
The parietal pleura is innervated by the intercostal and phrenic nerves and is sensitive to pain and touch.
The visceral and parietal pleura are two discontinuous layers.
A is correct. The R and L pleural cavities are separated from each other by the mediastinal structures B is correct. The recesses are only filled by a fully expanded lung during maximal inspiration C is correct. The parietal pleura shares the nerve supply of the structures overlying it ie. The chest wall (intercostals nerves) and the diaphragm and mediastinum (phrenic nerves). Being somatic nerves they are sensitive to pain and touch D is Incorrect. The parietal and visceral layers of pleura are continuous at the hilum of the lung
Which one of the following statements regarding surfactant is correct?
It is secreted by type 1 pneumocytes.
It decreases lung compliance.
It is soluble in water.
It is present in the foetal lung from 32 weeks.
A is incorrect. Type 2 pneumocytes. B is incorrect. It increases lung compliance by decreasing surface tension. C is incorrect. It is insoluble and floats on the surface of alveolar lining fluid. D is correct. After 32 weeks sufficient surfactant is present in the foetal lung.
Which one of the following agents reduces inflammation in asthma?
Budesonide is a steroid that helps reduce inflammation in asthma by reducing mast cell degranulation and synthesis of inflammatory mediators. A, B & E are each beta-adrenoceptor agonists that all cause bronchodilation and vary in duration of action. They may be used in conjunction with steroids. C is a muscarinic receptor antagonists that reduces parasympathetically mediated bronchoconstriction.