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 10-14, 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 satiety-sensitive 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