Moves the skeleton and produces heat.
Transports oxygen and nutrients to tissue.
Produces egg or sperm to continue the human species.
Supports the body and protects internal organs.
Removes waste products from the blood.
Exchanges oxygen and carbon dioxide between the blood and air.
Regulates body functions by means of impulses.
Regulates the body by means of hormones.
Destroys pathogens that enter the body.
Changes food to simpler chemicals to be absorbed.
Is a barrier to pathogens and to chemicals.