AP PSYCHOLOGY

Detailed explanation-1: -Leptin’s ability to reduce food intake occurs within the brain by decreasing NPY (a potent stimulant of food intake) and by increasing –melanocyte-stimulating hormone (−MSH), an inhibitor of food intake. Peripherally, leptin acts synergistically with CCK to reduce meal size.

Detailed explanation-2: -The two hormones most closely associated with energy homeostasis leading to sensations of hunger and satiety are ghrelin and leptin.

Detailed explanation-3: -The relevant satiety signals must arise in either the stomach and upper duodenum or in the lower small intestine. A transplanted stomach study has shown that a hormone released from the stomach is responsible for the termination of a single meal.

Detailed explanation-4: -During meals, signals such as CCK, GLP-1, and distension of the stomach that arise from the gut (stomach and intestine) trigger nerve impulses in sensory nerves traveling to the hindbrain. These satiation signals synapse with neurons in the nucleus of the solitary tract (NTS) where they influence meal size.