EXAMINING GOD'S UNIVERSE: Problems and Solutions to Gas Exchange
For the most part all life requires oxygen. Only a few one-celled
organisms can carry out respiration without oxygen. In fact to some of
them oxygen is even poisonous. All one celled organisms exchange gas
across the cell membrane. Respiration is the creation of energy by the
cell using the gases it is able to obtain. Respiration requiring oxygen is
called aerobic; respiration without oxygen is called anaerobic. Each
solution is as we shall see is designed specifically to operate in a
particular environment. Although the challenges at the one celled level
are fairly simple, requiring only the presence of gas molecules and a wet
surface for exchange, the real challenges come when you have
multi-cellular organisms, where most of its cells do not have direct
access to the environment.
Problems
facing gas exchange:
When looking at more complex
organisms there are several problems that need to be solved in order for
gas exchange to take place.
2.
Most plants and animals have a protective surface, such as skin, or
the exoskeleton of insects, or the waxy layer of cells that covers leaves.
3.
In most animals gas exchange across a membrane must be forced in
some way, that is, you need to bring the gas to the membrane.
4.
Gas exchange surfaces are very fragile, so they need to be
protected from damage by the environment.
5.
It must connect and be integrated with the circulatory system. The
entire system must be able to connect to a system to transport the gases
to the rest of the organism.
6.
It
must also work with the behavioral systems of the organism. That is, the
organism has to know how to breathe. All organisms with complex gas
exchange systems breathe instinctively, that is, the information on how to
use the system is built into the organism.
All designs must incorporate solutions to most or all of six problems. Proper gas exchange is essential to the survival of an organism. We will be looking at four different designs that solve these problems, systems in plants, the gill system, the tracheal system and the lung system, and also a few special systems that are not part of any of these. Within each system there also are a variety of solutions designed specifically to solve additional problems. As you read through these keep in mind that each system is a solution to a problem. And as we discussed earlier only intelligence seeks solutions to problems.