- active removal of toxins
- nitrogen-waste processing
- ion excretion
- xenobiotic metabolism
- waste transport
Operational definition
Allocation function.
Energy and matter devoted to transforming, sequestering, transporting, or removing harmful, excessive, or metabolically unusable substances.
It includes:
- xenobiotic metabolism;
- nitrogen-waste processing;
- metal sequestration;
- ion excretion;
- active toxin export;
- regulated waste removal.
Excretion is not necessarily mere disposal; it may be essential to acid–base, osmotic, and elemental homeostasis.