Final answer:
The brain sending signals to organ Y to metabolize substance X until it is within normal limits represents a negative feedback loop, which is essential for maintaining homeostasis in the body.
Step-by-step explanation:
The scenario described where the brain detects too much of substance X in the blood and sends a message to organ Y to metabolize the excess substance until it is within normal limits is an example of a negative feedback loop. This type of feedback loop is crucial for maintaining homeostasis within the body.
When levels of a certain substance are too high or too low, the body triggers mechanisms to bring the levels back to normal. The process involves a sensor that detects the deviation from homeostasis, a control center (usually the brain or an endocrine gland) that processes this information, and an effector (such as organ Y) that acts to correct the deviation by either increasing or decreasing the production of the substance.
A practical example of a negative feedback loop is the regulation of blood glucose levels. When blood glucose levels rise, insulin is released to lower them. Conversely, when glucose levels are too low, glucagon is released to increase them. These mechanisms ensure that blood glucose levels stay within a healthy range, demonstrating how the negative feedback loop functions in homeostasis.