Which hormone is secreted into the bloodstream by fatty tissue to signal the hypothalamus that the body has had enough food, reducing appetite and increasing the feeling of being full? leptin lippotor peptic acid adrenalin?

The correct answer is "leptin".

Leptin is a hormone secreted by adipose tissue to signal satiety. This hormone works on the arcuate nucleus of the hypothalamus where the satiety center is located. Another hormone, ghrelin, works to signal hunger and also works on the arcuate nucleus of the hypothalamus.