HUMAN BIOLOGY

194 ChapteR 10

10. Most carbon dioxide in the blood is in the form
    of.
    a. carbon dioxide c. carbonic acid
    b. carbon monoxide d. bicarbonate

CritiCaL thinkinG

1. Cases of accidental carbon monoxide poisoning occur
   when someone builds a charcoal fire in an enclosed area.
   Assuming help arrives in time, what would be the most
   effective treatment: placing the victim outdoors in fresh air
   or administering pure oxygen? Explain your answer.


2. Skin divers sometimes purposely hyperventilate. Doing
   so doesn’t increase the oxygen available to tissues. It does
   raise blood pH (making it more alkaline), and it decreases
   the blood level of carbon dioxide. Based on your reading
   in this chapter, how is hyper ventilation likely to affect the
   neural controls over breathing?


3. When you sneeze, abdominal muscles abruptly contract,
   pushing your diaphragm upward. Given the discussion of
   the respiratory cycle in Section 10.4, why does this change
   expel air out your nose?


4. Underwater, we humans can’t compete with whales and
   other air-breathing marine mammals, which can stay
   submerged for extended periods. At the beach one day
   you meet a surfer who tells you that special training
   could allow her to swim underwater without breathing
   for an entire hour. From what you know of respiratory
   physiology, explain why she is mistaken.


5. The red blood cell enzyme carbonic anhydrase contains
   the metal zinc. We obtain zinc in food, especially red meat
   and some seafoods. A zinc deficiency doesn’t reduce the
   number of red blood cells, but it does reduce the amount
   of carbon dioxide released into the blood. Explain why this
   effect impairs respiratory functioning.

The health dangers of first and

secondhand tobacco smoke are

well known. New studies show

that thirdhand smoke can be as or

more toxic. Thirdhand smoke is the

residue that settles on furniture,

drapes, and other objects in a

smoky environment. The residues

aren’t inert. They give off noxious

substances that circulate in the

air and can be inhaled. Until 2014,

scientists had no conclusive

evidence that the toxins actually

harm health. Now, a team using mice as test subjects has

shown that contact with these residues caused serious

damage to organs such as the liver and lungs. It also slowed

wound healing. If more studies support these findings, you will

be hearing more and more about health concerns associated

with thirdhand smoke.

your future

Southern Illinois University/Science Source

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