Gas Exchange Review Unit#4 Lesson 1 Questions
1. What purpose is served by the respiratory system?
The main function of the respiratory system is gas exchange. This refers to the process
of Oxygen and Carbon Dioxide moving between the lungs and blood. The respiratory
system brings oxygen into the blood so the blood can distribute to all of the body’s cells.
It also turns oxygen into nutrients and removes carbon dioxide from the body. The
respiratory system also regulates the body’s pH balance.
2. Why is the respiratory surface for terrestrial organisms inside rather
than outside the body?
Amphibians, frogs, and fish all use their skin as a respiratory surface to obtain oxygen
and eliminate carbon dioxide. Humans cannot diffuse oxygen through their skin. They
can only exchange about 1% of their carbon dioxide through there skin. The same goes
for terrestrial animals; they are only able to exchange a very small amount of gases
through their skin. As a result, they must develop more efficient lungs in order for their
bodies to obtain an efficient amount of oxygen for bodily functions. Thus, their
respiratory systems are inside their bodies. Also, respiration must take place in a moist
environment. Aquatic animals live in water, so they can exchange gas outside of their
bodies seeing that a moist environment is provided to them. The same cannot be said
for terrestrial animals since they live on land, and therefore since all of the fluid is inside
their bodies, respiration must take place inside.
3. How does the human respiratory system achieve a large surface
The human respiratory system achieves a large surface area through bronchioles and
alveoli. Each bronchiole ends in a grape-like cluster of tiny sacs called alveoli. If all of
the alveoli in an average human lung were spread out on a smooth surface, they cover
bout 70 -90 meters squared. As you can see, these structures greatly increase the
surface area of the lungs, which helps to maximize the volume of oxygen and carbon
dioxide that diffuses to and from the lungs.
4. Explain the process of breathing. 1. Inhalation beings with the intercostal muscles contracting. The muscles associated
with the ventral surface of the rib cage lif