Which system transports oxygen, wastes, nutrients, hormones, and heat around the body?

• A. Digestive system
• B. Endocrine system
• C. Nervous system
• D. Circulatory system

Answer: (D)

Transport of oxygen, wastes, nutrients, hormones, and heat throughout the body is the function of the circulatory system. Blood carries oxygen from the lungs to tissues and returns carbon dioxide to the lungs to be exhaled. Nutrients absorbed from food travel in the blood to cells all around the body. Metabolic wastes are carried away by the blood to organs like the kidneys and liver for processing and excretion. Hormones released by glands travel through the bloodstream to reach their target organs. Heat produced by metabolic activity is distributed by blood flow, helping to regulate body temperature. This broad transport network is possible because of the circulatory system, which includes the heart, blood, and blood vessels.

Other systems don’t fit this role precisely. The digestive system breaks down food and absorbs nutrients but doesn’t move them through the body. The endocrine system distributes hormones but isn’t the main carrier for oxygen, nutrients, and wastes. The nervous system coordinates signaling and responses rather than serving as the transport network for these substances.