Metabolism and Energy Balance Practice Questions

The glucostatic theory proposes that the maintenance of glucose availability is crucial for life because glucose is the most important energy substrate for the brain.

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The lipostatic theory suggests that the amount of fat in the body is regulated to maintain energy stores. All the storage tissue in the body is fat.

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Ghrelin is released when the stomach is empty and initiates a meal. As soon as the concentration of ghrelin goes down, you stop eating. This is a short-term regulation of hunger.

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Melanin blocks aMSH, a hormone that suppresses appetite. When melanin blocks aMSH, the MC4 receptor is left open, leading to increased food intake. This also increases dopamine levels, giving a pleasurable feeling when eating.

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Stretch receptors in the stomach signal satiety as the stomach expands during meals. The release of cholecystokinin (CCK) is triggered by fatty acids, peptides, and aromatic amino acids, which signals the brain to stop eating and activates digestion enzymes in the pancreas. This is a short-term regulation of satiety.

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Leptin acts as a negative feedback signal between adipose tissue (fat) and the brain. When you eat more, fat levels increase, and leptin is released, telling the brain to stop eating and reducing food intake. This is a long-term regulation of energy balance.

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Low leptin levels lead to decreased energy and metabolism, resulting in a feeling of weakness.

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Leptin-deficient mice do not release leptin, leading to no reduction in food intake. This causes obesity in Obob mice.

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