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CNS Depressants: Alcohol and Nicotine01:27

CNS Depressants: Alcohol and Nicotine

Ethanol, a clear colorless alcohol, has been consumed by humans for millennia, but its effects on the body are far from benign. At lower doses, it induces decreased inhibitions and loquaciousness, leading to its social appeal. However, it can cause severe consequences at higher doses, such as coma and respiratory depression, due to its zero-order elimination kinetics. Chronic ethanol abuse wreaks havoc on multiple organ systems, particularly the CNS and the liver. Abrupt cessation of ethanol...
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Metabolic States of the Body: The Postabsorptive State01:18

Metabolic States of the Body: The Postabsorptive State

The postabsorptive state usually starts about four hours after a meal and lasts until the next meal is eaten. During this time, the digestive system stops absorbing nutrients, and the body uses stored energy reserves to maintain stable blood glucose levels.
Initially, glycogen stored in the liver is broken down to release glucose into the bloodstream, while glycogen in the muscles is broken down to supply glucose for energy directly within the muscle cells. As glycogen stores diminish,...
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Metabolic States of the Body: Fasting and Starvation01:24

Metabolic States of the Body: Fasting and Starvation

During the initial hours of fasting, the body uses up its glycogen stores as an energy source. Once these glycogen reserves are depleted, the body begins breaking down stored triglycerides and structural proteins. During this stage, glycerol becomes a key substrate for gluconeogenesis, while free fatty acids undergo beta-oxidation to provide energy for tissues, such as skeletal muscle. In the fasting state, the body spares protein breakdown as much as possible to conserve muscle and structural...
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Regulation of Food Intake01:30

Regulation of Food Intake

Short-term regulation of food intake primarily involves neural signals from the gastrointestinal (GI) tract, blood nutrient levels, and GI tract hormones. Communication between the gut and brain via vagal nerve fibers plays a significant role in evaluating the contents of the gut. Clinical studies have shown that protein ingestion produces a more prolonged response in these nerve fibers compared to an equivalent amount of glucose. Additionally, the activation of stretch receptors caused by GI...
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Metabolic States of the Body: The Absorptive State01:25

Metabolic States of the Body: The Absorptive State

During the absorptive state, which lasts approximately four hours after a meal, the body absorbs nutrients from the gastrointestinal tract. The carbohydrates, proteins, and lipids we consume are broken down into monosaccharides, amino acids, and free fatty acids for absorption. While carbohydrates and proteins are absorbed as-is, lipids are absorbed in their broken-down forms and then re-esterified into triglycerides within enterocytes before being packaged into chylomicrons. These absorbed...
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Optimal Foraging00:48

Optimal Foraging

How animals obtain and eat their food is called foraging behavior. Foraging can include searching for plants and hunting for prey and depends on the species and environment.
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