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Human Performance
2.3.3.1 Metabolism
What do we use oxygen for?
Oxygen plays a key role in metabolism, a process that involves:
fuel + oxygen water + CO2 (carbon dioxide) + energy
The fuel is the food we eat, which is converted into glucose/blood sugar. Along
with oxygen, it is transported to cells where metabolism takes place.
By-products of metabolism include water, carbon dioxide, and energy.
Water and carbon dioxide are transported back to the lungs, while energy
powers bodily function.
The brain and nerve cells are especially sensitive to low oxygen levels.
Although the brain accounts for only 2% of body weight, it consumes about 20%
of the absorbed oxygen.
2.3.3.2 Blood
Our blood has three primary functions:
- Transporting oxygen and nutrients.
- Defending against microorganisms.
- Regulating body temperature.
Blood consists of:
- Plasma
- Blood cells:
o Red blood cells – carry oxygen.
o White blood cells – fight infections.
o Platelets – assist in clotting and healing.
Blood cells make up approximately 45-50% of the blood volume.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 138
