Question: Why do exchange surfaces have to be moist? Why does diffusion
work best when molecules have to cr…
Why do exchange surfaces have to be moist? Why does diffusion
work best when molecules have to cross only a short distance? Why
is a high surface area required?
o What is partial pressure? How do you calculate (or estimate)
o Why is gas exchange more difficult for animals with gills than
animals with lungs? What advantage does countercurrent exchange
give for gas exchange in the fish?
o What is the pathway of oxygen entry into our lungs, from the
time we inhale until it reaches the gas exchange surfaces in the
alveoli? List the major structures, in correct order.
o What is negative pressure breathing? Which main muscle groups
are involved in inhalation and exhalation? Which
(inhalation/exhalation) is passive, which active?
o What tissue protects the human trachea and bronchial trees
from collapsing during the pressure changes of breathing? Why don’t
the bronchioles have this?
o In which structure does actual gas exchange take place in
humans? What prevents the alveoli membranes from sticking together
during exhalation? What is pulmonary surfactant? Why do premature
babies often suffer from respiratory distress syndrome?
o What is a respiratory pigment? In humans, which molecule is
specialized to transport oxygen in the blood? In which cells do we
find this pigment? Why can’t we meet our oxygen needs by using the
02 dissolved directly in the blood?
o What’s the relationship between CO2, bicarbonate (HC03- ), and
carbonic acid (H2CO3)? In what form is most CO2 carried in our
blood? What is the role of carbonic anhydrase in gas exchange?
o Which blood gas (02 or CO2,) controls breathing under normal
conditions? How are its levels sensed by respiratory centers in the