Necessary Life Functions & Survival Needs

Maintaining Boundaries

The ability of an organism to keep its "inside" distinct from its "outside," like the skin protecting internal organs.

Movement

All activities promoted by the muscular system, including propelling the body and moving substances through internal organs.

Responsiveness (or Irritability)

The ability to sense changes (stimuli) in the environment and react to them.

Digestion

The process of breaking down ingested food into simple molecules that can be absorbed into the blood.

Metabolism

A broad term for all chemical reactions that occur within body cells, including breaking down substances, building larger structures, and producing energy (ATP).

Excretion

The process of removing wastes (excreta) from the body.

Reproduction

The production of offspring, occurring on the cellular level (for growth and repair) or the organismal level.

Growth

An increase in size, usually accomplished by an increase in the number of cells.

Survival Needs

Factors required to maintain life, including nutrients (food), oxygen, water, and appropriate temperature and atmospheric pressure