10- Hunger and Satiety

Controls of Hunger/Satiety

• Neural Mechanisms

• Hormonal Mechanisms

• Mechanical Mechanisms

• Chemical Mechanisms

Hormones of Hunger/Satiety

• peptide YY

• CCK

• Insulin

• Leptin

• Ghrelin

PYY (peptide yy)

• Secreted from ileum and LI

• Targets brain

• Anorexigenic

CCK (cholecystokinin)

• Secreted from duodenum

• Targets pancreas, gallbladder, and brain (lipase/bile salts)

• Anorexigenic

Insulin

• Secreted by pancreatic beta cells

• Anorexigenic

Leptin

• Secreted by fat (adipose)

• Targets arcuate neurons of hypothalamus

• Anorexigenic

Ghrelin

• Secreted by the stomach (when empty)

• Targets arcuate neurons in hypothalamus

• Orexigenic

Vagus Nerve (CN X)

Distension of the stomach and duodenum causes satiety via THIS

Glucostatic Theory

Reduced glucose utilization in these critical brain regions leads to perception and expression of hunger.

Causes an increase in action potential firing frequency of neurons in the satiety center of the hypothalamus

Causes a decrease in action potential firing frequency of neurons in hunger center of the hypothalamus

Behavioral Obesity

Typically obesity can be considered THIS, which requires comprehensive lifestyle interventions.

BMI

= mass (kg)/height (m)2

19

19-25

25-30

30

40

BMI < _ underweight

BMI _-_ normal

BMI _-_ overweight

BMI _+ obese

BMI _+ severely obese

Underweight than Overweight

Being THIS has a higher risk of death than being THIS.

Dietary Adherence

THIS is the primary predictor of weight loss, not the type of diet.

Calories

THIS/10 = pounds

Anorexigenic

Satiety

Orexigenic

Hunger