Ingestive Behaviour

Question 1

What is the focus of ingestive behavior research?

Answer 1

Understanding neural circuits underlying appetite and satiety and how these interact with hormonal and cephalic (higher-order) processes.

Question 2

How is obesity often viewed in modern research?

Answer 2

As both a result of poor impulse control and compulsive behavior, with parallels to drug addiction in terms of stress, craving, and reward mechanisms.

Question 3

What is the role of genetics in obesity?

Answer 3

Single-gene disorders account for less than 10% of obesity; familial resemblance in energy and macronutrient intake also contributes.

Question 4

What was learned from parabiotic mouse experiments?

Answer 4

Ob/Ob mice lack leptin production but respond to it.
Db/Db mice produce leptin but are insensitive to it (leptin receptor defect).

Question 5

Why do most obese individuals have high leptin levels?

Answer 5

Due to leptin resistance, which may involve reduced leptin transport into the brain.

Question 6

What is basal metabolism?

Answer 6

The energy required to fuel the brain and organs and maintain temperature.

Question 7

What is the “thrifty phenotype” hypothesis?

Answer 7

A genetic adaptation beneficial in scarce food environments but problematic in high-calorie diets, contributing to obesity and type 2 diabetes.

Question 8

How does the body defend its weight set point?

Answer 8

By dynamically regulating metabolic rate, decreasing it during caloric restriction and increasing it during caloric excess.

Question 9

What is homeostasis in ingestive behavior?

Answer 9

The active regulation of energy stores, water, and other variables to maintain physiological balance.

Question 10

How does satiety signaling regulate homeostasis?

Answer 10

Satiety mechanisms often monitor the activity of corrective processes, such as stopping drinking before water absorption.

Question 11

What triggers osmometric thirst?

Answer 11

Increases in blood osmolality due to dehydration or salty meals.

Question 12

What triggers volumetric thirst?

Answer 12

Reductions in blood plasma volume or pressure.

Question 13

What are osmoreceptors, and how do they function?

Answer 13

Neurons that detect cell shrinkage due to high osmolality, triggering thirst.

Question 14

Which brain regions regulate thirst?

Answer 14

The subfornical organ (SFO) and organum vasculosum of the lamina terminalis (OVLT), which respond to changes in osmolality and angiotensin II levels.

Question 15

How does the SFO contribute to anticipatory thirst regulation?

Answer 15

SFO activity decreases as drinking begins, predicting the restoration of homeostasis.

Question 16

What is the glucostatic theory of eating?

Answer 16

Falling blood glucose triggers hunger, while rising glucose levels after a meal signal satiety.

Question 17

What is the incentive theory of eating?

Answer 17

Food consumption is driven by the positive incentive value of food, even beyond immediate energy needs.

Question 18

How does ghrelin influence hunger?

Answer 18

Ghrelin levels rise during fasting and signal hunger to the hypothalamus, decreasing after a meal.

Question 19

What gastrointestinal hormones signal satiety?

Answer 19

Peptide YY (PYY), CCK, and GLP-1, which act on the hypothalamus and brainstem.

Question 20

What is the role of leptin in long-term satiety?

Answer 20

Produced by fat cells, leptin signals energy storage levels and modulates sensitivity to short-term hunger and satiety signals.

Question 21

How does leptin resistance affect weight regulation?

Answer 21

High leptin levels fail to inhibit hunger due to reduced receptor sensitivity.

Question 22

What is the role of the arcuate nucleus in appetite regulation?

Answer 22

It integrates hunger and satiety signals, with distinct neuron groups responding to each.

Question 23

How do cephalic (head) factors influence eating?

Answer 23

They include hedonic factors (food palatability), learned cues (timing, context), and autonomic responses like salivation.

Question 24

What is cue-potentiated feeding?

Answer 24

Learned cues, such as the sight or smell of food, can trigger eating even when energy needs are met.

Question 25

What is sensory-specific satiety?

Answer 25

he phenomenon where the reward value of a specific food decreases after consumption, promoting dietary variety.

Question 26

What is the “buffet effect”?

Answer 26

The tendency to eat more when presented with a variety of foods, even if sated on one type.

Question 27

How does social facilitation affect eating behavior?

Answer 27

People tend to eat more and have longer meals in social settings, especially with friends or family.

Question 28

How does stress affect eating?

Answer 28

Chronic stress often leads to hyperphagia (increased eating), while severe stress can cause hypophagia (reduced eating).

Question 29

What types of food are preferred during stress-induced eating?

Answer 29

High-energy, calorie-dense foods like those rich in sugar and fat.

Question 30

What are the main signals regulating appetite and satiety?

Answer 30

Metabolic signals (glucose/lipid sensing), gastrointestinal hormones, long-term signals (leptin), and cephalic factors (hedonic and learned cues).