Forms the external body covering; protects deeper tissue from injury; synthesizes vitamin D; location of cutaneous (pain, pressure, etc.) receptors; and sweat and oil glands.
Protects and supports body organs; provides a framework the muscles use to cause movement; blood cells are formed within bones; stores minerals.
Allows manipulation of the environment, locomotion, and facial expression; maintains posture; produces heat.
Fast-acting control system of the body; responds to internal and external changes by activating appropriate muscles and glands.
Glands secrete hormones that regulate processes such as growth, reproduction, and nutrient use (metabolism) by body cells.
Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc.; the heart pumps blood.
Picks up fluid leaked from blood vessels and returns it to blood; disposes of debris in the lymphatic stream; houses white blood cells involved in immunity.
Keeps blood constantly supplied with oxygen and removes carbon dioxide; the gaseous exchanges occur through the walls of the air sacs of the lungs.
Breaks food down into absorbable units that enter the blood for distribution to body cells; indigestible foodstuffs are eliminated as feces.
Eliminates nitrogenous wastes from the body; regulates water, electrolyte and acid-base balance of the blood.
Production of offspring. Testes produce sperm and male sex hormone; ducts and glands aid in delivery of viable sperm to the female reproductive tract. Ovaries produce eggs and female sex hormones; remaining structures serve as sites for fertilization and development of the fetus. Mammary glands of female breast produce milk to nourish the newborn.