111.  The pontine respiratory neurons  
A.  are located in the medulla oblongata in the brain.
B.  are active only during inspiration.
C.  are active only during expiration.
D.  play a role in switching between inspiration and expiration.
E.  is essential for respiratory rhythm.

112.  Rhythmicity of breathing involves  
A.  conscious effort and control.
B.  stimulation of inspiration. Expiration is automatic.
C.  pontine respiratory group as a necessary part.
D.  a set pattern of inspiration – expiration that is always the same.
E.  the pre-Bötzinger complex of the ventral respiratory group.

113.  A baby holding its breath will  
A.  be termed a “blue baby”.
B.  have brain cells damaged because of low blood oxygen levels.
C.  suffer heart damage because of increased pressure in the aorta.
D.  automatically start to breathe when the CO₂ levels in the blood reach a high enough value.
E.  automatically start to breathe when oxygen levels decrease slightly.

114.  It is possible to consciously control the rate and depth of respiration.  
TRUE

115.  Apnea is the slowing of respiration as occurs during sleep.  
FALSE

116.  The chemosensitive area of the brain is located in the  
A.  pons.
B.  cerebral peduncles.
C.  cerebellum.
D.  hypothalamus.
E.  medulla oblongata.

117.  Mr. Smith hypoventilates and retains too much carbon dioxide. Which of the following receptors is stimulated by an increase in carbon dioxide?  
A.  irritant receptors
B.  pressure receptors
C.  osmoreceptors
D.  peripheral chemoreceptors
E.  baroreceptors

118.  When carbon dioxide levels in the blood increase, the  
A.  condition is called hypocapnia.
B.  pH of the blood increases.
C.  blood becomes more acidic.
D.  number of hydrogen ions in the blood decreases.
E.  blood becomes more alkaline.

119.  After hyperventilating for several minutes, a person may develop short periods of apnea because  
A.  blood pH would drop and inhibit inspiration.
B.  oxygen in the lungs has not had time to diffuse into the blood.
C.  the level of oxygen has increased and inhibits the inspiratory center.
D.  the level of CO₂ decreases below the level necessary to stimulate the inspiratory center.
E.  blood pH will rise and stimulate expiration.

120.  Blood oxygen levels  
A.  are more important than carbon dioxide levels in the regulation of respiration.
B.  need to change only slightly to cause a change in respiration rate.
C.  within the normal PO₂ range have little effect on regulation of respiration.
D.  in venous blood and arterial blood are about the same.
E.  never change enough to influence respiration.