Summarize and cite information from your textbook in your own words to support your writing for the following questions:

1. Describe the 3 important mechanisms for returning blood back to the heart when someone is exercising in an upright position.

2. Describe and differentiate between internal and external respiration.

3. Describe the process in which oxygen and carbon dioxide are transported in the blood.

4. Using your text and the article attached above, address the following in approximately 500 words:

• What are the proposed physiologic mechanisms that would cause blood doping to increase aerobic performance?
• What are the physiologic risks involved in blood doping?
• Explain why elite aerobic athletes might choose to blood dope, despite the risks.

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