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CH. 17 Energy Balance and Temperature Regulation Do We Have Enough Energy? • Understand what energy is and what it is used for • Know how much energy is actually used and how much we lose as heat • Understand what metabolic rate and basal metabolic rate are a measure of • Know the types of energy balances that exsist • Understand what nutrients are and how we regulate nutrient intake Energy • Input – energy stored in the bonds of ingested food • Output – the use of that energy – External work • Energy expended during skeletal voluntary skeletal muscle contractions – Internal work • All forms of biological expenditure that do not perform work outside of the body – Involuntary skeletal muscle contractions – All life sustaining activities that are always occurring Energy Consumption • How much energy do we actually use? • Lose about 75% as heat • Metabolic rate – – – – Rate of energy use Energy used/unit time Expressed in calories, and kilocalories (Calories) BMR – Basal metabolic rate • Minimum waking rate of internal energy expenditure • Influenced by thyroid hormone Neutral Energy Balance • Energy input = energy output • Three states of energy balance – Neutral energy balance • Amount of intake = to output – Body weight remains constant – Positive energy balance • Amount of intake > output – Excess stored s adipose, weight increases – Negative energy balance • Amount of intake < output – Body must use stored energy, weight decreases laali.kau.edu.sa Nutritious and Delicious • Nutrient – An ingested chemical that is used for growth, repair, and maintenance of the body – Two categories • Macronutrients – Must consume in large quantities – Water, carbohydrates, lipids , and proteins • Micronutrients – Small quantities needed – Minerals and vitamins • Calories – Kcal – Measure of the capacity to do work Metabolic States • Absorptive state – Nutrients are being absorbed and my be used immediately to meet needs • Postabsorptive state – Stomach and small intestines empty, energy needs met from stored fuel Regulation of Appetite • Short-term regulators – Ghrelin – produces sensation of hunger – Peptide YY (PYY) – sensation of satisfaction – CCK – sensory stimulus of vagus nerve (suppressor) • Long-term regulators (adiposity signals) – Leptin – Insulin • Arcuate nucleus of hypothalamus – NPY - stimulator – Melanocortin - suppressor Psychosocial and Environmental Influences • Eat out of habit • Social custom • Familial customs mindfully.org