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Learning Objectives To consolidate our understanding of the neural mechanisms involved in controlling satiation and hunger Recap - do you know what they do? Ghrelin Insulin Glucagon VMH LH CCK Ghrelin • Hormone released from the stomach. • The less food in the stomach - the higher the level of ghrelin released • Gastric bands lower levels of ghrelin • It works directly on the hypothalamus and ‘switches on’ feeding behaviour. Insulin • Released from the pancreas • Enables the body to convert glucose in the blood to glycogen for storage. • The pancreas may become unable to release either enough insulin or become damaged. These problems will lead to diabetes. Glucagon • This is the hormone released from the pancreas that will turn stored glycogen back to glucose. • The glucose is then released into the blood for use. V-M-H • • • • Ventro-Medial Hypothalamus. This area of the brain inhibits feeding. Research in rats quite conclusive. If the rat’s VMH is damaged you will end up with obese rats – the ‘stop’ signal no longer works LH - ‘GO GO GO’ • An area of the hypothalamus called the Lateral Hypothalamus (Lunch Here I come!) • This area stimulates feeding. • Research on rats confirmed that if the LH is damaged the rat stops eating (aphagia) as the ‘on switch’ no longer works CCK – STOP! • Cholecystokinin is a hormone released from the duodenum. • It is released once the food has passed from the stomach to the small intestine. • It acts on the hypothalamus as a satiety signal when there is food present. Hunger, Eating and Satiation: the process Eating Increase in Ventromedial Satiety blood glucose hypothalamus reached activated Hunger develops Lateral Blood glucose Eating stops hypothalamus levels drop activated Review: neural explanations for eating & satiation