Why is rising blood glucose considered negative feedback in this situation? A) This is actually an example of positive feedback because blood glucose rises to return to the set point. B) Because having low blood sugar is bad and anything out of the set range has negative consequences for the body. C) Because when glucose returns to the set point the initial stimulus goes away and the control center stops sending out the signal.
Answer (1)
In biology, negative feedback is a control mechanism that helps maintain balance or homeostasis in the body. It works by reversing any change in a physiological condition. The situation you're asking about involves blood glucose levels, which are tightly regulated by the body through negative feedback mechanisms.
When blood glucose levels rise, perhaps after eating, this triggers the pancreas to release insulin. Insulin is a hormone that helps cells take in glucose from the blood, thus lowering blood glucose levels back to the set point. Once the glucose levels have returned to normal, the pancreas reduces the release of insulin.
Now, let's break down the options:
A) This is not an example of positive feedback. Positive feedback amplifies changes rather than reversing them, which is the opposite of what's needed to maintain glucose levels at a set point.
B) While it is true that low blood sugar can have negative consequences, this does not explain why it is specifically considered negative feedback.
C) This option accurately describes negative feedback: the system reduces the output of insulin once the glucose levels return to normal, stopping the initial response to rising glucose levels. Hence, negative feedback works to remove the stimulus (high blood glucose) once balance is restored.
Therefore, the correct choice is C: Because when glucose returns to the set point, the initial stimulus goes away and the control center stops sending out the signal. This describes how negative feedback operates by counteracting changes that deviate from a set point, helping maintain homeostasis.
