Testing Your Knowledge

1. Why do large, active animals require circulatory systems? Give three examples of circulatory systems that are adapted to the activity level of the organism.

2. How do open and closed circulatory systems differ?

3. What role do pigments play in the respiratory and circulatory systems of vertebrates?

4. Maintaining the proper proportions of formed elements in the blood is essential for health. What can happen when the blood contains too few or too many red blood cells, white blood cells or platelets?

5. What process discussed in the chapter illustrates positive feedback? Negative feedback?

6. Name three ways that the circulatory system helps to maintain homeostasis.

7. What causes the heartbeat? Why is the heart sometimes referred to as two hearts that beat in unison?

8. What types of changes in blood vessels would raise blood pressure?

9. Where does lymph originate? What propels it through the lymphatic vessels?

1. How is a red blood cell’s structure adapted for its function?

2. Name three illnesses doctors could treat if medical technology could isolate, mass produce, and reimplant a person’s healthy bone marrow stem cells.

3. Describe the abnormality or disrupted process that causes each of the following medical conditions:

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