When a jogger starts to run, the rate at which his muscles produce CO₂ rises sharply. But the CO₂ in his blood rises only slightly before he starts to breathe faster and his heart starts beating stronger. Soon his increased rate of CO₂ production is balanced by an increased rate of CO₂ removal. This would be an example of __________ feedback because the jogger's circulatory and respiratory systems are __________.

• A. positive; improving the operating conditions in the jogger's body
• B. positive; decreasing the CO₂ concentration
• C. positive; restoring the CO₂ concentration to the set point
• D. negative; acting in opposition to one another
• E. negative; acting to oppose the increase of CO₂ from the set point or normal range

Answer: (E)

Verified step by step guidance

1. Identify the physiological process described: The jogger's body is responding to an increase in CO2 production by increasing breathing and heart rate to remove CO2.
2. Understand the concept of feedback mechanisms: Feedback mechanisms are processes that help maintain homeostasis in the body. They can be positive or negative.
3. Define negative feedback: Negative feedback is a process that counteracts a change, bringing the system back to its set point or normal range.
4. Analyze the scenario: The jogger's increased CO2 production is countered by increased CO2 removal through faster breathing and stronger heartbeats, which reduces CO2 levels back to normal.
5. Conclude the type of feedback: Since the body's response is to oppose the increase in CO2 and restore balance, this is an example of negative feedback, acting to oppose the increase of CO2 from the set point or normal range.