Engineer Battalion Promotion Board Practice Exam

Circulatory system. This system includes the heart as the pumping organ, the blood as the transport fluid, and the blood vessels as the channels that carry blood throughout the body. Its primary job is to move oxygen, nutrients, and hormones to cells and to remove wastes and carbon dioxide. The heart drives the flow, blood vessels form the network, and the blood itself enables the transport. That combination is what defines the circulatory system. The other systems serve different roles: the respiratory system handles gas exchange, the nervous system governs signaling and control, and the endocrine system manages hormone signaling. Some texts also use cardiovascular system when focusing on the heart and vessels, but the circulatory system is the standard term for this question.