51.  The lungs have  
A.  one blood flow route and one lymphatic supply.
B.  two blood flow routes and one lymphatic supply.
C.  one blood flow route and two lymphatic supplies.
D.  two blood flow routes and two lymphatic supplies.
E.  three blood flow routes and one lymphatic supply.

52.  When the inspiratory muscles contract,  
A.  thoracic volume increases.
B.  pleural pressure increases.
C.  the alveolar pressure increases.
D.  expiration occurs.
E.  thoracic volume decreases.

53.  Which of the following statements is true?  
A.  As thoracic volume increases, alveolar pressure (P_alv) increases.
B.  In expiration, the thoracic volume increases.
C.  Constriction of bronchioles assists breathing.
D.  As alveolar volume increases, alveolar pressure (P_alv) decreases.
E.  Pressure is directly proportional to volume.

54.  For air to flow into or out of the lungs, there must be  
A.  a volume gradient established between the atmosphere and the alveoli.
B.  a temperature gradient between the atmosphere and the alveoli.
C.  a pressure gradient established between the atmosphere and the alveoli.
D.  a diffusion gradient between the atmosphere and the alveoli.
E.  None of these choices is correct.

55.  During expiration, the alveolar pressure must be  
A.  greater than atmospheric pressure.
B.  less than atmospheric pressure.
C.  equal to atmospheric pressure.
D.  greater than pleural pressure.
E.  None of these choices is correct.

56.  Surfactant facilitates alveolar ventilation by  
A.  decreasing the surface tension between water molecules on the lining of the alveoli.
B.  decreasing thoracic compliance.
C.  attracting water to the alveolar surface.
D.  increasing the surface area for gas exchange.
E.  increases the surface tension between fluid and the alveoli.

57.  During inspiration, contraction of the diaphragm causes the volume of Mr. Jones’ thoracic cavity to increase and the pleural pressure to decrease. The pressure in his alveoli (P_alv) will  
A.  decrease below atmospheric pressure (P_B), causing air to move out of his lungs.
B.  become greater than atmospheric pressure (P_B), causing air to move into his lungs.
C.  decrease below atmospheric pressure (P_B), causing air to move into his lungs.
D.  become greater than atmospheric pressure (P_B), causing air to move out of his lungs.
E.  does not change.

58.  Which of the following factors keeps the alveoli expanded?  
A.  a pneumothorax
B.  negative pleural pressure
C.  alveolar pressure being equal to atmospheric pressure
D.  a reduction in surfactant
E.  negative intra-alveolar pressure

59.  Air in the pleural cavity is called  
A.  emphysema.
B.  respiratory distress syndrome.
C.  a pneumothorax.
D.  pneumonia.
E.  forced expiration.

60.  Whose law explains that an increase in volume causes a decrease in pressure?  
A.  Henry’s Law
B.  Dalton’s Law
C.  Charles Law
D.  Boyles Law