Psych Notes: Hypothalamus

How does it work?

Hunger
Lateral: when stimulated, it makes you hungry. When destroyed, you will never be hungry again
Ventromedial: when stimulated, you feel full. When damaged, you will never feel full again

Two Theories

1. Leptin: a protein produced by bloated fat cells
• Hypothalamus senses rises in leptin and will curb eating and increase activity
• Can leptin injections help me?
2. Set Point: Hypothalamus acts like a thermostat
• we are meant to be in a certain weight range 
• when we fall below weight our body will increase hunger and decrease energy expenditure (Basic Metabolic Rate)
• What happens if we go above our set point?

Body Chemistry and Hormones

• Insulin
• Converts glucose (sugar) into fat
• When glucose levels drop, hunger increases
• an increase of insulin lowers blood sugar and triggers hunger
• Testosterone and Estrogen
• Testosterone is a male sex hormone, though there are small levels of it in females
• Estrogen is a female sex hormone, though there are small levels of it in males as well
• Orexin and Leptin
• Orexin is responsible for appetite and increasing the craving for food
• Leptin is responsible for feeling full and signals the brain that it has had enough food

Hormone	Tissue	Response
Orexin increase	Hypothalamus	Increases hunger
Ghrelin increase	Stomach	Increases hunger
Insulin increase	Pancreas	Increases hunger
Leptin Increase	Fat cells	Decreases hunger
PPY increase	Digestive tract	Increases hunger

The Psychology of Hunger

-Externals: people whose eating is triggered more by the presence of food than internal factors

Eating Disorders

1. Bulimia Nervosa: Characterized by binging (eating large amounts of food) and purging (getting rid of the food)
2. Anorexia Nervosa: Starve themselves to below 85% of their normal body weight
• see themselves as fat
• vast majority are women