Appetite - Podcast Version 0:00 / 0:00 1x 0.25x 0.5x 0.75x 1x 1.25x 1.5x 1.75x 2x In order to ensure that we continue to eat food to fuel our bodies, we experience the sensation of hunger. In this article, we will look at the key signals involved in the control of appetite, including those that promote hunger and those that cause satiety. Pro Feature - 3D Model You've Discovered a Pro Feature Access our 3D Model Library Explore, cut, dissect, annotate and manipulate our 3D models to visualise anatomy in a dynamic, interactive way. Learn More Appetite Control Centre The appetite control centre is located in the hypothalamus. Within in hypothalamus lies the arcuate nucleus, which plays a key role in the control of appetite. The appetite centre contains both primary and secondary neurones. The primary neurones process external signals, be it neuronal, hormonal or nutritional. The secondary neurones are then responsible for co-ordinating the inputs received via the primary neurone. These primary neurones are either excitatory or inhibitory. The neurotransmitters released by excitatory and inhibitory neurones are: Excitatory: Neuropeptide Y (NPY) and Agouti-related peptide (AgRP). These promote hunger. Inhibitory: POMC and CART. POMC can be cleaved into other neurotransmitters such as α-MSH and β-endorphin. These suppress hunger. Hormonal Signals From the Gut Ghrelin is a peptide hormone produced mainly in the stomach but also in small quantities in other tissues such as the pancreas. It is released from the stomach wall when the stomach is empty. This stimulates the excitatory primary neurones, and therefore stimulates appetite. When the stomach is full, ghrelin release is inhibited, thus the appetite stimulus is also inhibited. PYY (full name – peptide tyrosine tyrosine) is a short peptide hormone released by cells in the ileum and colon in response to feeding. It inhibits the excitatory primary neurones of the arcuate nucleus. This causes appetite suppression. From the Body Leptin is a peptide hormone released into the blood by adipocytes (fat cells). Leptin stimulates the inhibitory neurones and inhibits the excitatory neurones in the arcuate nucleus to cause suppression of appetite. Insulin is a hormone released from beta cells in the islets of Langerhans of the pancreas. This suppresses appetite in a similar way to leptin. Clinical Relevance Leptin Deficiency Leptin deficiency may arise from deletion of the leptin gene causing severe obesity, hyperphagia (excessive eating) and a reduced metabolic rate. However, this is incredibly rare. Leptin deficiency can also be found in conditions and syndromes where there is significant lipodystrophy. The effects of leptin deficiency can be reversed with the use of exogenous leptin. Do you think you’re ready? Take the quiz below Pro Feature - Quiz Appetite Question 1 of 3 Submitting... Skip Next Rate question: You scored 0% Skipped: 0/3 More Questions Available Upgrade to TeachMePhysiology Pro Challenge yourself with over 2100 multiple-choice questions to reinforce learning Learn More Frequent questions What is the role of the appetite control centre in the hypothalamus? The appetite control centre, located in the hypothalamus, regulates hunger and satiety by processing various signals through primary and secondary neurones. Primary neurones respond to neuronal, hormonal, and nutritional inputs, while secondary neurones coordinate these signals to influence appetite. How does ghrelin affect appetite? Ghrelin is a hormone produced mainly in the stomach that stimulates appetite by activating excitatory neurones in the arcuate nucleus when the stomach is empty. Its release decreases when the stomach is full, leading to a reduction in appetite stimulation. What hormones are involved in appetite suppression? Leptin and insulin are key hormones that suppress appetite by acting on the neurones in the arcuate nucleus. Leptin, released by fat cells, inhibits excitatory neurones, while insulin, produced by the pancreas, has a similar appetite-suppressing effect. What is the significance of leptin deficiency in relation to appetite? Leptin deficiency can lead to severe obesity and excessive eating due to its crucial role in regulating appetite. This condition is rare but can occur in specific syndromes involving lipodystrophy, and its effects may be managed with exogenous leptin. How do PYY and leptin interact with appetite regulation? PYY, released from the ileum and colon after feeding, inhibits excitatory neurones in the arcuate nucleus, leading to appetite suppression. Similarly, leptin, released by adipocytes, also suppresses appetite by activating inhibitory neurones and inhibiting excitatory ones. Rate This Article