121.  The major regulator of respiration is the plasma concentration of  
A.  oxygen.
B.  carbon dioxide.
C.  water vapor.
D.  nitrogen.
E.  chloride.

122.  A greater than normal amount of CO₂ in the blood is called  
A.  hypercapnia.
B.  hypoxia.
C.  hyperdioxemia.
D.  hypodioxemia.

123.  The Hering-Breuer reflex  
A.  causes erratic respirations.
B.  helps prevent overinflation of the lungs.
C.  has its sensory components in the sympathetic nerves.
D.  is a normal response to increased oxygen content in the blood.
E.  limits how much air a person can expire.

124.  During exercise, ventilation initially increases due to  
A.  increased blood carbon dioxide levels stimulating baroreceptors.
B.  decreased blood oxygen levels stimulating chemoreceptors.
C.  decreased blood pH levels stimulating baroreceptors.
D.  limb movements that stimulate the respiratory center.
E.  abrupt changes in metabolism or blood gases.

125.  The highest level of exercise that can be performed without causing a significant change in blood pH is called the  
A.  Hering-Breuer reflex.
B.  aerobic threshold.
C.  anaerobic threshold.
D.  lactic acid tolerance level.

126.  Which of the following is NOT a respiratory adaptation to exercise training?  
A.  vital capacity increases
B.  tidal volume at maximal exercise will increase
C.  increased minute ventilation after training
D.  after training, respiratory rate at rest is lower

127.  Which of the following is mismatched?  
A.  bronchitis – inflammation of the bronchi
B.  emphysema – destruction of the alveolar walls
C.  pulmonary fibrosis – loss of elastic recoil in the lung
D.  cystic fibrosis – replacement of lung tissue with fibrous connective tissue
E.  smokers – chronic obstructive pulmonary disease

128.  A respiratory disease characterized by decreased chloride ion diffusion out of cells and dehydrated respiratory secretions is  
A.  bronchitis.
B.  emphysema.
C.  cystic fibrosis.
D.  pulmonary fibrosis.
E.  lung cancer.

129.  A patient has severe pneumonia, which has thickened the respiratory membrane. Despite oxygen therapy, he still has rapid respiration and feels as if he is not getting enough air. This is because  
A.  the oxygen increases the stimulation of the carotid and aortic bodies.
B.  the oxygen stimulates the respiratory center to increase the respiratory rate.
C.  his blood pH increased and stimulated an increase in his respiratory rate.
D.  even though he is receiving enough oxygen, carbon dioxide and hydrogen ions accumulate in his blood and cause the respiratory rate to continue to increase.
E.  oxygen cannot diffuse across the thickened membrane.

130.  Which of the following is an effect of aging on the respiratory system?  
A.  vital capacity is unchanged
B.  minute ventilation rates increase
C.  residual volume increases
D.  gas exchange in the lungs remains unchanged