True: It takes 20 seconds for blood to circulate the entire body., Blood vessels are tubes that carry the blood around the body., When we breathe,, we inhale air containing oxygen into our lungs., False: If you were lay out all of the arteries, capillaries and veins, they would stretch about 50,000 miles, Veins carry oxygenated blood back to the heart to be pumped to the lungs to become deoxygenated., There are between 3 and 4.5 million red blood cells in the human body.,

Circulatory System

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