Download Chapter 1 Answers

Chapter 26 Answers
Respiration
Visual Understanding
1. Figure 26.9
Explain what would happen to carbon dioxide transport if a person was poisoned with a
chemical that blocked the actions of carbonic anhydrase?
The major mechanism of transport of carbon dioxide in the blood would become
dissolved molecular CO2. Some sodium bicarbonate would still form because the reaction
between carbon dioxide and water would still occur, only very slowly.
2. Figure 26.11
What conclusions can you draw about cigarette smoking and women’s health? Explain.
The incidence of lung cancer in men followed a sharp increase about 20 years after men
began smoking in large numbers. As the numbers of cigarettes smoked leveled off and
held steady, the number of lung cancer sufferers also leveled off at about 90 men per
100,000 per year. The number of cigarettes smoked for women has not yet leveled off
and held steady, and it has surpassed the number for men.
The incidence of lung cancer for women looks very much as if it will follow the same sort
of curve that the incidence of lung cancer for men followed. However, since it looks as if
the number of cigarettes smoked per capita may still be increasing, it follows that the
incidence of lung cancer for women may end up much higher than it did for men. We will
need at least another 20 years of data to have a better idea of what will happen.
Challenge Questions
1. Sometimes when people are eating, they take a bite that is too big or one that is not
completely chewed, and when they swallow it becomes stuck partway down the
esophagus. Because the esophagus is a soft, muscular tube that lies just behind the
trachea, a somewhat stiffer tube, this bulge of food in the esophagus can sometimes push
hard enough on the trachea to close it off. In this case, people have been trained to do the
Heimlich maneuver, which is a method of pushing up rapidly on the diaphragm,
compressing the lungs. Why might this help?
If you push up rapidly on the diaphragm and compress the lungs, the air that was in the
lungs must go someplace. Its only choice is to push up through the trachea and try to
escape through the mouth and nose.
Since the trachea is being pinched closed by the food in the esophagus, the strong blast of
air coming up the trachea from the lungs can sometimes bump into the stuck place with
enough force to shove the food back into the throat and out the mouth. It often takes
several tries, but the food will fly out of the mouth with considerable force, just like a bb
from an air gun or a wad of paper from a straw.
2. How is it that cigarette smoking be linked to an increased incidence of many kinds of
cancer?
The p53 protein constantly patrols the DNA in your cells looking for damage. If it finds a
problem, it sets in motion events to either repair the DNA or kill the cell to prevent
mutations, such as those that cause cancer, from reproducing. There are chemicals in
cigarette smoke that attach to the gene that controls the manufacture of the p53 protein,
keeping it from being made. So because the cigarette smoke keeps p53 protein from
being made, the p53 protein is not available in the cell to check on the DNA, and if any of
the mutations that cause any of the different types of cancer occur, there is no way to stop
it.