Outline and Evaluate the Role of Neural Mechanisms Involved in Controlled Eating and Satiation

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Outline and evaluate the role of neural mechanisms involved in controlled eating and satiation (24 marks) Hunger is activated by many different cues, both biological and environmental. The body is controlled by homeostasis which is how we maintain our constant internal environment. Homeostasis is controlled by a negative feedback loop which assumes that all body variables have a set point. The set point helps the body regulate its weight and therefore knows how much the person should be eating. Hunger is based on fat stores (lipostatic hypothesis), glucose levels (glucostatic hypothesis) and cellular energy. The dual centre model of feeding describes the two areas of the hypothalamus involved in eating behaviour. When we are hungry we start eating, the body’s blood glucose levels increase and so do ghrelin levels. When we are full the Ventro Medial Nucleus (VMN) of the hypothalamus is activated which inhibits eating and satiety is reached. Blood glucose levels drop again after eating and the Lateral hypothalamus is activated (which initiates feeding) and we become hungry and the process starts again. There are several neurotransmitters in the body which are also involved in eating regulation. Ghrelin is a hormone which is released when the stomach is empty so it triggers eating. The second most important hormone is leptin and this is released from adipocytes, and the more fat a person has the more leptin is released and it acts as a satiety signal so stops food intake. Cummings et al (2004) did a study into the effects of ghrelin on people. He used 6 male participants and they were monitored every 5 minutes between their midday meal and when they requested their evening meal. Their hunger levels were also assessed every 30 minutes. Ghrelin levels fell after eating lunch, were at their lowest after 70 minutes and peaked at the time they requested their

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