Chapter 6, Problem 3CT

Several years ago the deaths of several airline travelers led to warnings about economy-class syndrome. The idea is that economy-class passengers dont have as much leg room as passengers in more expensive seats, so they are more likely to sit essentially motionless for long periods on flightsconditions that may allow blood to pool and clots to form in the legs. This condition is called deep-vein thrombosis, or DVT. Given what you know about blood flow in the veins, explain why periodically getting up and moving around in the planes cabin during a long flight may lower the risk that a clot will form.

Figure 40.17 Varicose veins are veins that become enlarged because the valves no longer close properly, allowing blood to flow backward. Varicose veins are often most prominent on the legs. Why do you think this is the case?

Figure 16.10 Which of the following statements about the circulatory system is false? a. Blood in the pulmonary vein is deoxygenated. b. Blood in the inferior vena cava is deoxygenated. c. Blood in the pulmonary artery is deoxygenated. d. Blood in the aorta is oxygenated.