1) Maintaining Boundaries- keeping the internal environment (inside) remains distinct from the external environment surrounding it (outside). (Example: skin protects organs from drying out).
2) Movement- includes activities promoted by the muscular system and movement occurs when a substance such as blood circulates throughout the body.
3) Responsiveness- the ability to sense changes (stimuli) in the environment and then respond to them. (Example: involuntarily pulling your hand away from sharp, broken glass (the painful stimuli).
4) Digestion- the breaking down of ingested foodstuffs to simple molecules that cab be absorbed into the blood.

5) Metabolism- (state of change), a board term including all chemical reactions that occur with body cells.
6) Excretion- the process of removing excreta (wastes) from the body.
7) Reproduction- can occur at a cellular or organismal level. Meaning cells divide and reproduce two identical daughter cells used for the body growth or repair. Or the reproduction of a human organism by a sperm uniting with an egg, fertilizing the egg which develops into the offspring.
8) Growth- the increase in size of a body part or the organism.

4) The Functional Characteristics Necessary to Maintain Life in Humans