Chapter 30

Chapter 30 - Chapter 30: Nutrition and Digestion Impacts,...

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Chapter 30: Nutrition and Digestion
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Adipose cells are fat-storing cells An adaptation that helped our ancestors survive times of food scarcity Adipose cells produce leptin, a hormone which acts on the brain to control hunger Americans are among the fattest people in the world estimated at 60% of adults are overweight Obesity is over-abundance of fat in adipose tissue Impacts, Issues: Hominids, Hips, and Hunger
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Obese people do not have less leptin than normal, but leptin receptors may not work properly. Gastric bypass – surgery to close off part of stomach and most of small intestine Cholecystokinin may promote appetite suppression Elderly tend to have low appetites that sometimes endanger health New drugs that block cholecystokinin may help elderly stay nourished Impacts, Issues: Hominids, Hips, and Hunger
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Nutrition All foods contain nutrients needed for survival Nutrition describes the process of acquiring and processing nutrients in useable form Nutrients fall into 5 major categories. lipids carbohydrates proteins minerals vitamins
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Cells Obtain Energy from Nutrients Most energy used by cells is derived from carbohydrates and fats These molecules are broken down and their subunits are broken down during cellular respiration Energy is released and is captured in ATP
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Cells Obtain Energy from Nutrients The energy in nutrients is measured in calories A calorie is the amount of energy required to raise 1 gram of water 1 degree Celsius Food calorie content is measured in units of 1000 calories (kilocalories), also known as Calories (capital C) The average human burns 70 Calories per hour at rest, and up to 20 Calories per minute during exercise
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Cells Obtain Energy from Nutrients
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Lipids Lipids are essential nutrients Lipids are diverse and contain long chains of carbon atoms and are insoluble in water Specialized lipids can be synthesized by some animals. Others require essential fatty acids (lipid building blocks) from their food.
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Lipids 3 principal types of lipids Triglycerides (fats used as an energy source) Phospholipids (component of cell membranes) Cholesterol (component of cell membranes, sex hormones, and bile)
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Animals Store Energy as Fat When an animal’s diet provides excess energy, the excess is stored as fat 3600 Calories are stored in each pound of fat Fats are excellent energy storage molecules A concentrated energy source compared to proteins and carbohydrates Hydrophobic lipids avoid excess water accumulation in body Animals that maintain elevated body temperatures use fats to insulate their bodies.
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Carbohydrates Carbohydrates are used as an energy source, but can have structural uses as well. Carbohydrates are broken down into sugars
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Chapter 30 - Chapter 30: Nutrition and Digestion Impacts,...

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