Identify two parts of the nervous system that are involved in hunger signals and what those parts do to create hunger. Then explain one piece of scientific evidence that supports a role of each part of the nervous system in hunger signals.

Question

What will be an ideal response?

Answer 1

The vagus nerve sends signals about glucose and fatty acids from the liver to the NST of the medulla. Severing the vagus nerve prevents increases in eating that typically occur when fatty acids are blocked or when a glucose deficit is created by injecting an animal with 2-DG. The NST of the medulla passes on signals about body levels of glucose and fatty acids to the hypothalamus, particularly the arcuate nucleus. Lesions of the NST prevent increases in eating that typically occur when fatty acids are blocked or when a glucose deficit is created by injecting an animal with 2-DG. The periventricular nucleus (PVN) of the hypothalamus and the lateral hypothalamus both receive information about nutrients from the arcuate nucleus. The arcuate nucleus contains NPY/AgRP neurons that release neuropeptide Y (NPY) and agouti-related protein (AgRP), which result in increased eating and lowered metabolism by exciting cells in the PVN and lateral hypothalamus. Injecting NPY into the PVN of rats results in increased eating and body weight.