Final answer:
The mechanism that adjusts a body system to normalize a regulated variable is known as negative feedback, which corrects deviations by counteracting changes.
Step-by-step explanation:
The mechanism by which a body system makes functional adjustments in order to bring back a regulated variable such as body temperature or blood glucose levels to normal is defined by negative feedback. In a negative feedback loop, if a regulated variable is outside the normal range, it triggers a response designed to counteract the deviation and bring the variable back into the normal range.
For example, when blood glucose levels rise, insulin is released to lower them, and conversely, if glucose levels are low, glucagon is released to increase them, corrections are made in both cases through negative feedback mechanisms.