Florida Basic Recruit Training Program High Liability (First Aid) Practice Exam

Which structures are known as a system of tubes through which blood flows?

1. Valves

2. Nerves

3. Blood vessels

4. Muscles

The correct answer is: Blood vessels

Blood vessels are the correct answer as they are the primary structures responsible for transporting blood throughout the body. This system includes arteries, veins, and capillaries, each serving a specific function in circulating oxygen-rich blood from the heart to various tissues and returning deoxygenated blood back to the heart. Arteries carry blood away from the heart, while veins return blood to the heart. Capillaries connect the two and facilitate the exchange of oxygen, carbon dioxide, nutrients, and waste products at the cellular level. The extensive network of blood vessels ensures that all tissues receive the necessary blood supply to function properly. The other options do not serve this function. Valves regulate blood flow and prevent backflow within certain blood vessels, but they are not the main structures through which blood flows. Nerves are involved in transmitting signals throughout the body and do not transport blood. Muscles produce movement and generate force but are not involved in the blood flow system.