肥胖的生物学基础_培训课件.ppt

Factors predispose to obesity Genetic – familial tendency. Sex – women more susceptible . Activity – lack of physical activity. Psychogenic – emotional deprivation, depression . Social class – poorer classes. Alcohol – problem drinking. Smoking – cessation smoking. Prescribed drugs – tricyclic derivatives. Weight Gain: Medications Disease Examples Diabetes Insulin, sulfonylureas Depression Tricyclics Seizures Valproic acid, Tegretol Hypertension Clonidine, α-blockers, β-blockers Hormones Progesterone Weight Gain: How Does It Happen? Energy imbalance calories consumed not equal to calories used Over a long period of time Due to a combination of several factors Individual behaviors Social interactions Environmental factors Genetics Weight Gain: Energy In 3500 calories = 1 pound 100 calories extra per day = 36,500 extra per year = 10.4 lbs weight gain Question: How much is 100 calories? Answer: Not very much! 1 glass skim milk, or 1 banana, or 1 slice cheese, or 1 tablespoon butter Evolving Pathology More in and less out = weight gain More out and less in = weight loss Hypothalamus control center for hunger and satiety Endocrine disorder where are the hormones? Leptin Protein hormone secreted by adipocytes Levels correlate with lipid content of cells Leptin acts on the hypothalamus to reduce hunger and to stimulate energy expenditure Ghrelin Hormone secreted in the stomach Acts on the hypothalamus to stimulate appetite Levels peak just before meals and drop afterward Bad News for Dieters Leptin Dieting decreases leptin levels Reducing metabolism, stimulating appetite Ghrelin Levels in dieters are higher after weight loss The body steps up ghrelin production in response to weight loss The higher the weight loss, the higher the ghrelin levels * * * Figure 9.2: Fat Cell Development. Fat cells are capable of increasing their size by 20-fold and their number by several thousandfold. * * * Leptin is a hormone made by fat tissue that acts on brain to reg