| Feature | Short-term Regulation | Long-term Regulation |
|---|---|---|
| Primary Goal | Meal initiation and termination | Maintenance of body weight/fat stores |
| Key Hormones | Ghrelin, CCK, Insulin | Leptin |
| Primary Source | Digestive tract (Stomach/Intestines) | Adipose tissue (Fat cells) |
| Mechanism | Responds to immediate nutrient presence | Responds to overall energy reserves |
Identify the Direction: When analyzing hormone effects, always clarify if the hormone is orexigenic (increases hunger) or anorexigenic (decreases hunger) to avoid confusing their roles.
Lesion Logic: Remember that 'lesioning' (damaging) a center produces the opposite effect of that center's normal function; for example, damaging the satiety center (VMH) causes a lack of satiety (overeating).
Feedback Loops: Be prepared to describe the negative feedback loop where a stimulus (low energy) leads to a response (eating) which then removes the original stimulus (satiety).
The 'One Center' Myth: A common mistake is viewing the LH or VMH as the sole controllers of eating; in reality, they are part of a highly integrated network involving the ARC and the paraventricular nucleus.
Leptin Resistance: Students often assume high leptin always prevents obesity, but in many cases of chronic overeating, the brain becomes 'resistant' to leptin signals, failing to register satiety despite high fat stores.
Ghrelin Timing: It is a misconception that ghrelin only responds to physical emptiness; it also follows a circadian rhythm and can be triggered by the anticipation of a scheduled meal.