FIGURE 9.7 The appetite hormones Ghrelin: Hormone secreted by empty stomach; sends “I’m hungry” signals to the brain.
Insulin: Hormone secreted by pancreas; controls blood glucose.
Leptin: Protein hormone secreted by fat cells; when abundant, causes brain to increase metabolism and decrease hunger.
Orexin: Hunger-triggering hormone secreted by hypothalamus.
PYY: Digestive tract hormone; sends “I’m not hungry” signals to the brain.