Ingestive Behaviour Flashcards
What is the focus of ingestive behavior research?
Understanding neural circuits underlying appetite and satiety and how these interact with hormonal and cephalic (higher-order) processes.
How is obesity often viewed in modern research?
As both a result of poor impulse control and compulsive behavior, with parallels to drug addiction in terms of stress, craving, and reward mechanisms.
What is the role of genetics in obesity?
Single-gene disorders account for less than 10% of obesity; familial resemblance in energy and macronutrient intake also contributes.
What was learned from parabiotic mouse experiments?
Ob/Ob mice lack leptin production but respond to it.
Db/Db mice produce leptin but are insensitive to it (leptin receptor defect).
Why do most obese individuals have high leptin levels?
Due to leptin resistance, which may involve reduced leptin transport into the brain.
What is basal metabolism?
The energy required to fuel the brain and organs and maintain temperature.
What is the “thrifty phenotype” hypothesis?
A genetic adaptation beneficial in scarce food environments but problematic in high-calorie diets, contributing to obesity and type 2 diabetes.
How does the body defend its weight set point?
By dynamically regulating metabolic rate, decreasing it during caloric restriction and increasing it during caloric excess.
What is homeostasis in ingestive behavior?
The active regulation of energy stores, water, and other variables to maintain physiological balance.
How does satiety signaling regulate homeostasis?
Satiety mechanisms often monitor the activity of corrective processes, such as stopping drinking before water absorption.
What triggers osmometric thirst?
Increases in blood osmolality due to dehydration or salty meals.
What triggers volumetric thirst?
Reductions in blood plasma volume or pressure.
What are osmoreceptors, and how do they function?
Neurons that detect cell shrinkage due to high osmolality, triggering thirst.
Which brain regions regulate thirst?
The subfornical organ (SFO) and organum vasculosum of the lamina terminalis (OVLT), which respond to changes in osmolality and angiotensin II levels.
How does the SFO contribute to anticipatory thirst regulation?
SFO activity decreases as drinking begins, predicting the restoration of homeostasis.
What is the glucostatic theory of eating?
Falling blood glucose triggers hunger, while rising glucose levels after a meal signal satiety.
What is the incentive theory of eating?
Food consumption is driven by the positive incentive value of food, even beyond immediate energy needs.
How does ghrelin influence hunger?
Ghrelin levels rise during fasting and signal hunger to the hypothalamus, decreasing after a meal.
What gastrointestinal hormones signal satiety?
Peptide YY (PYY), CCK, and GLP-1, which act on the hypothalamus and brainstem.
What is the role of leptin in long-term satiety?
Produced by fat cells, leptin signals energy storage levels and modulates sensitivity to short-term hunger and satiety signals.
How does leptin resistance affect weight regulation?
High leptin levels fail to inhibit hunger due to reduced receptor sensitivity.
What is the role of the arcuate nucleus in appetite regulation?
It integrates hunger and satiety signals, with distinct neuron groups responding to each.
How do cephalic (head) factors influence eating?
They include hedonic factors (food palatability), learned cues (timing, context), and autonomic responses like salivation.
What is cue-potentiated feeding?
Learned cues, such as the sight or smell of food, can trigger eating even when energy needs are met.
What is sensory-specific satiety?
he phenomenon where the reward value of a specific food decreases after consumption, promoting dietary variety.
What is the “buffet effect”?
The tendency to eat more when presented with a variety of foods, even if sated on one type.
How does social facilitation affect eating behavior?
People tend to eat more and have longer meals in social settings, especially with friends or family.
How does stress affect eating?
Chronic stress often leads to hyperphagia (increased eating), while severe stress can cause hypophagia (reduced eating).
What types of food are preferred during stress-induced eating?
High-energy, calorie-dense foods like those rich in sugar and fat.
What are the main signals regulating appetite and satiety?
Metabolic signals (glucose/lipid sensing), gastrointestinal hormones, long-term signals (leptin), and cephalic factors (hedonic and learned cues).
