3. Physiology
        3.11. Neurophysiology
3.11.4. Hunger

Hunger

[Ref: WG22:p235-240]

Feeding centre vs satiety centre

Hypothalamus regulates appetitde by interaction of 2 areas:

  1. Feeding centre
    * Lateral, in the bed nucleus of the medial forebrain bundle
  2. Satiety centre
    * Medial, in the ventromedial nucleus

NB:

 

Factors that increase food intake

Factors that decrease food intake

Afferent mechanisms

4 hypothesis, not mutually exclusive

1. Lipostatic hypothesis

Leptin

Function
Leptin receptor

db gene is responsible for production of leptin receptor

Receptor has different form

The significant form is mostly found in the arcuate nuclei

Also found in brown adipose tissue
--> Leptin may also increase the heat-producing activities of brown adipose tissue

Conclusion

2. Gut peptide hypothesis

Ghrelin

Function
Conclusion

3. Glucostatic hypothesis

Glucose

Activity of satiety centre in the ventromedial nuclei
--> At least partly dependent on glucose utilisation by the neurons in it

When glucose utilisation by these neurons is low
--> Decreased activity
--> Hunger

When glucose utilisation is high
--> Increased activity
--> Sated

Thus,

4. Temperature

Cold temperature --> Increased food intake

Warm temperature --> Decreased food intake

But,
Temperature is unlikely to play a role in regulation

Others

Social, environmental, cultural factors all play a role



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