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Regulation of Eating Behaviour

Section Overview

1

Role of the Hypothalamus

Focusing on the LH and VMH centers.
2

Hormonal Influences

Ghrelin (hunger) and Leptin (satiety).
3

Neural Pathways

The role of the Arcuate Nucleus and other brain regions.
4

Mechanism Summary

How the opposing systems regulate homeostasis.

Understanding Energy Balance

Introduction

Eating behaviour is regulated by complex neural and hormonal mechanisms that ensure energy balance and maintain homeostasis. A key site of this regulation is the brain, particularly the hypothalamus, along with peripheral hormones like ghrelin and leptin that signal hunger and satiety.

Key Regulators Glossary

🧠

Lateral Hypothalamus (LH)

Often called the 'hunger centre'; promotes hunger signals.
🧠

Ventromedial Hypothalamus (VMH)

Considered the 'satiety centre'; signals fullness.
🍽️

Ghrelin

'Hunger hormone' produced by the stomach; stimulates appetite.
⚖️

Leptin

'Satiety hormone' produced by fat tissue; suppresses appetite.

The Hormonal Balance: Hunger vs Satiety

✅
Ghrelin (The Promoter)Levels rise before meals and fall after eating. Ghrelin activates NPY/AgRP neurons to stimulate appetite.
❌
Leptin (The Suppressor)Concentration increases with fat stores. Leptin acts on the hypothalamus to suppress appetite and increase energy expenditure.

Coordinating the Hypothalamic Centers

🤔
Wait, why are there two opposing centers (LH and VMH) so close to each other?
🦉
Together, the LH and VMH coordinate to maintain energy balance, sending and receiving signals about energy needs.

The Arcuate Nucleus Equation (ARC)

Appetite Stimulant Neurons = NPY + AgRP
Ghrelin activates NPY/AgRP neurons to promote hunger, while Leptin activates POMC/CART neurons to promote satiety.
Appetite Inhibitory Neurons = POMC + CART

Clinical Insight

💡

Leptin Resistance: In obesity, individuals may become leptin-resistant, meaning the brain no longer responds appropriately to leptin signals, which complicates appetite control.

Homeostatic Feedback Loop

Step Description Impact
1. Stomach is empty Ghrelin levels rise
2. Ghrelin acts on Hypothalamus Stimulates hunger centers
3. Food intake occurs Leptin secretion increases
4. Leptin acts on VMH Suppresses hunger / Signals stop
Regulation of Eating Behaviour Deck
Term
Brain structure for eating behaviour

What brain structure is primarily responsible for regulating eating behaviour?

Answer
Hypothalamus

The hypothalamus.

Term
Hunger centre

Which part of the hypothalamus is known as the "hunger centre"?

Answer
Lateral Hypothalamus (LH)

The Lateral Hypothalamus (LH).

Term
Effect of VMH stimulation

What effect does stimulation of the Ventromedial Hypothalamus (VMH) have?

Answer
Reduces Hunger

It reduces hunger and food intake, promoting satiety.

Term
Hunger hormone

What hormone is called the "hunger hormone"?

Answer
Ghrelin

Ghrelin.

Term
Ghrelin production site

Where is ghrelin primarily produced?

Answer
Stomach lining

In the stomach lining.

Term
Satiety hormone

What hormone is known as the "satiety hormone"?

Answer
Leptin

Leptin.

Term
Leptin production tissue

Which tissue produces leptin?

Answer
Adipose (fat) tissue

Adipose (fat) tissue.

Term
Leptin resistance

What happens in leptin resistance?

Answer
Impaired brain response

The brain does not respond properly to leptin, impairing appetite control.

Term
Arcuate nucleus neurons

Name the two key neuron populations in the arcuate nucleus that regulate appetite.

Answer
NPY/AgRP and POMC/CART

NPY/AgRP neurons (stimulate appetite) and POMC/CART neurons (inhibit appetite).

Term
Ghrelin action on arcuate nucleus

How does ghrelin influence the arcuate nucleus?

Answer
Activates NPY/AgRP neurons

It activates NPY/AgRP neurons to stimulate hunger.

Term
Leptin action on arcuate nucleus

How does leptin influence the arcuate nucleus?

Answer
Activates POMC/CART neurons

It activates POMC/CART neurons to suppress appetite.

Term
Brainstem role

What role does the brainstem play in eating behaviour?

Answer
Receives fullness signals

It receives fullness signals from the gastrointestinal tract.

Term
Emotional & reward integration

Which brain system integrates emotional and reward aspects of eating?

Answer
Limbic system & reward pathways

The limbic system and reward pathways (e.g., nucleus accumbens).

Term
Empty stomach hormone change

What occurs when the stomach is empty in terms of hormone levels?

Answer
Ghrelin levels rise

Ghrelin levels rise to stimulate hunger.

Term
Fat storage effect on leptin

How does increased fat storage affect leptin levels?

Answer
Leptin levels increase

Leptin levels increase to suppress appetite.

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🌸 Regulation of Eating Behaviour Quiz

1. Which hypothalamic region is called the “hunger centre”?

The LH promotes hunger and initiates eating behaviour when stimulated.

2. What hormone increases before meals and stimulates appetite?

Ghrelin levels rise before eating to signal hunger to the hypothalamus.

3. Damage to which hypothalamic area would likely cause overeating and obesity?

Lesions in the VMH reduce satiety signals, leading to excessive eating.

4. Which hormone is released by fat cells and suppresses appetite?

Leptin signals the brain to reduce food intake by indicating sufficient energy stores.

5. What is the function of NPY/AgRP neurons in the arcuate nucleus?

These neurons promote hunger when activated by hormones like ghrelin.

6. In obesity, why might leptin fail to suppress appetite effectively?

The brain becomes less sensitive to leptin signals, impairing appetite control.

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