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AP Psychology Physiology of Hunger Presentation
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Physiology of Hunger
The Physiology of Hunger: Introduction
What is Physiology:
How living things work biologically and chemically , or how organs of organisms work together.
What is hunger?
1. Compelling need or desire for food
2. The desire for food that arouses when an individual’s glucose levels go down, indicating that one’s sugar levels are low. The extreme lack of glucose is called hypoglycemia.
3. An uncomfortable sensation in your body when you lack food, which makes you weak, tired, and unable to concentrate
Insulin-Glucagon Cycle
Insulin and glucagon are antagonistic hormones that regulate blood glucose levels
- -insulin lowers blood glucose levels
- -glucagon raises blood glucose levels
- Maintains homeostasis
Related Brain Structures: The Hypothalamus
- Signals from intestines, liver, stomach sent by neurons that measure the levels of glucose in the blood and send signals to the hypothalamus
- Hypothalamus releases the hormones.
Case Studies
Specific hunger-related hormones
Washburn and Cannon
- Balloon into stomach to measure stomach contractions
- Contractions occurred when Washburn was hungry
- Hypothalamus: lateral (eat when hungry) and ventromedial (stop when full)
Keys
- Fed volunteers half their usual calories
- Volunteers became obsessed with food
- Due to the homeostatic system trying to obtain more nutrients and maintain body weight
Appetite Hormones also trigger hunger
- Leptin - metabolism goes up while hunger goes down
- Orexin - secreted by the hypothalamus which also triggers hunger
- Ghrelin - secreted by an empty stomach and sends “I’m hungry” signals to the brain
- Arcuate nucleus - secretes appetite suppressing or stimulating hormones
- If center is destroyed, starving animals have no interest in food
- Cholecystokinin - causes gallbladder to contract (inhibits appetite)
Washburn & Cannon
Ancel Keys
Physiology of Hunger Recap:
Proof that hunger is a physiological need
- Insulin/Glucagon cycle
- Related brain structures
- Chemicals in the body trigger hunger
- Washburn and Cannon Study
- Balloon in the stomach
- Keys' Study
- Men became obsessed with food once their food was restricted to half the usual calories