Transcript Chapter 10
Chapter 10 Internal Regulation Hunger • Animals vary in their strategies of eating, but humans tend to eat more than they need at the given moment. • A combination of learned and unlearned factors contribute to hunger. Hunger • The digestive system • Saliva → carbs • Stomach – Hydrochloric acid → proteins • Small intestine • Large intestine Hunger • The brain regulates eating through messages from the mouth, stomach, intestines, fat cells and elsewhere. Hunger • The main signal to stop eating is the distention of the stomach. – The vagus nerve – The splanchnic nerves Hunger • Duodenum • Cholecystokinin (CCK) Hunger • Glucose, insulin, and glucagon levels also influence feelings of hunger (see figures 1014, 10-15, 10-6). • Diabetes Fig. 10-14, p. 311 Fig. 10-15, p. 311 Fig. 10-16, p. 311 Hunger • Long-term hunger regulation is accomplished via the monitoring of fat supplies by the body. • Leptin Hunger • Information from all parts of the body regarding hunger impinge into two kinds of cells in the arcuate nucleus. Hunger • Output from the arcuate nucleus goes to the paraventricular nucleus of the hypothalamus. Hunger • Input from the hunger-sensitive neurons of the arcuate nucleus is inhibitory to both the paraventricular nucleus and the satietysensitive cells of the arcuate nucleus itself. Hunger • Output from the paraventricular nucleus acts on the lateral hypothalamus. – The lateral hypothalamus controls insulin secretion and alters taste responsiveness. • Animals with damage to this area refuse food and water and may starve to death unless force fed. Fig. 10-20, p. 315 Hunger • The lateral hypothalamus contributes to feeding Fig. 10-22, p. 316 Hunger • Ventromedial hypothalamus → satiety Hunger • People with a mutated gene for the receptors melanocortin overeat and become obese. – Melanocortin is a neuropeptide responsible for hunger. • Prader-Willis syndrome Hunger • Anorexia nervosa • Bulimia nervosa • Overeating and Binge-eating Disorder