Respiratory system
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The respiratory system is the system of organs in a human or any breathing organism has. It is usually made up of lungs or gills, a trachea (or windpipe), and a mouth or nose.
There are four main requirements for a respiratory system:
- It must remain moist at all times. If the respiratory system is dry, it does not have the essential elements of oxygen and carbon dioxide. It must be dissolved in water to be diffused across the membrane.
- It must be thin so gases can pass through it.
- There must be a source of oxygen.
- It must be closely connected to the blood stream (which delivers gases to and from cells).
