The importance of oxygen
Human bodies (and all other aerobic organisms), from a thermodynamics point of view, are basically engines that use the energy released from the chemical reaction between oxygen and fuel (food) to power all aerobic processes. This reaction is known as respiration.
In mammals which must regulate their body temperature very precisely, it is aerobic activity that is largely responsible for the generation of heat. It is also aerobic activity that provides muscles with the energy for all everyday activities such as walking (voluntary muscle control) and heart beats (involuntary muscle control).
Even in animals which largely depend upon environmental conditions to control their body temperature,such as amphibians and reptiles, aerobic activity is an important source of body heat and, as with mammals, muscle activity is powered by aerobic metabolism.
An aerobic experiment
To observe the effects of aerobic activity on the body's demand for oxygen a simple experiment can be performed in class.
Whenever the body requires more oxygen, two things become apparent. The first is that one's breathing rate increases1 in an attempt to get more oxygenated hemoglobin into the blood stream. The second apparent thing is that one's heart rate tends to increase in order to speed the oxygen rich blood to the site where it is needed.
1The involuntary need to breathe faster and to gasp for a breath is mediated mainly by the amount of carbon dioxide (a "waste" product of aerobic respiration) in the blood stream.
To observe this effect the following experiment can be performed.
Tips and Hints
- Have students work in groups of three.
- One student to act as a timer/recorder.
- The second student to act as a pulse-taker/observer. The observer should immediately stop the experiment if the "specimen" student experiences any stress that might indicate a problem. The observer should also ensure that the "maximum" 15 second rule is obeyed.
- The third student is the "specimen".
- A group may perform this experiment up to three times by exchanging roles.
- Emphasize that this is a scientific experiment, not a contest. Students should report their results as accurately and honestly as possible.
- Photocopy enough data sheets for the entire class. Outline the procedure and review the safety procedures before beginning the experiment.
Download the student experiment data sheet
Report and discuss your findings
Report your findings and discuss your results with other teams registered with the Polar Science Project. Login to the Polar Science site and post a new entry in the Polar Science Blog.
Weddell Seals
One of the amazing things about Weddell seals (and there are many) is their ability to stay underwater for up to 40 minutes without any apparent distress. This capacity to stay underwater for long periods of time does not appear to be directly related to their lung capacity, but rather to their amazing aerobic efficiency.
What is it about the cellular structure and cellular dynamic of Weddell seals that accounts for this amazing aerobic efficiency?
Scientists in the Antarctic are studying Weddell seals in the hopes of finding clues to help answer this and many other related scientific questions.
| What happens when a Weddell Seal dives? |
 |
It stops breathing.(Good idea underwater if you're an air breathing mammal!) |
 |
It lowers cardiac output. |
|
It lowers peripheral blood flow. |
 |
Its lungs collapse below 60 metres. (OUCH!) |
 |
But it still maintains aerobic metabolism.
How is that possible? |
Some Definitions
- Metabolism
- The sum of all chemical reactions, both anabolic (synthesis) reactions and catabolic (decomposition) reactions, within an organism.
- Anabolism
- The sum of all synthesis reactions in an organism.
- Catabolism
- The sum of all decomposition reaction in an organism.
- Aerobic respiration
- A type of cellular respiration requiring oxygen.
- Anaerobic Respiration
- A type of cellular respiration not requiring oxygen.
Close This Window When You Have Finished
