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R e g u l a t i o n o f f o o d i n t a k e
Lecture 3
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Hunger
Appetite
Satiety
It is craving for food and is associated withobjective sensations as hunger contractions ofthe stomach.
It is a desire for specific types of food insteadof food in general.
It is the opposite of hunger and means a feelingof fulfillment in the quest for food
Definitions
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Hypothalamic centers
1- The feeding (hunger) center
It lies in the lateral hypothalamus.
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Hypothalamic centers
1- The feeding (hunger) center
It lies in the lateral hypothalamus.
When it is stimulated in experimental animals, itcauses hyperphagia( eating behavior) .
Destruction of this center causes lack of the desire
for food, progressive weight loss, muscleweakness and fatal anorexia
The feeding center is chronically active . It istransiently inhibited by the satiety center after food
ingestion.
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Hypothalamic centers
2- The satiety center
It lies in the ventromedial nuclei of the hypothalamus.
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Hypothalamic centers
2- The satiety center
Destruction of this center causes hyperphagia andextreme obesity (hypothalamic obesitysyndrome).
Its stimulation causes aphagia (complete satiety
and cessation of eating)
It lies in the ventromedial nuclei of the
hypothalamus.
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Hypothalamic obesity syndrome
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Fifth level
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Other centers
1- The amygdala and the prefrontal cortex
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Other centers
1- The amygdala and the prefrontal cortex
They are closely coupled with the hypothalamus.
Their destruction causes omniphagia; a type ofmoderate hyperphagia where the mechanism
controlling the type and quality of food eaten islost, leading to attempting to eat all sort of objects.
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Other centers
2- Brain stem centers
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Other centers
2- Brain stem centers
They control the actual mechanisms of feeding as
salivation, chewing and swallowing.
They are excited by signals from the hypothalamus.
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Factors regulating
food intake
II) Short termregulation
1-Alimentary factors
2-Psychological factors
) Long termegulation
1-Nutritional regulation
-Effect of body temperature
-Feedback signals fromadipose tissue
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Long term regulation
Nutritional regulation
qWhen the nutrient stores fall below normal, thefeeding center becomes highly active and the
person exhibits increased hunger.qOn the other hand, when the nutrient stores areabundant, the person loses hunger and develops astate ofsatiety.
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Long term regulation
Nutritional regulation
The glucostatictheory
The lipostaticand
aminostatictheories
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Long term regulation
Effect of body temperature
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Long term regulation
Feedback signals from adipose tissue
Leptin
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Long term regulation
Feedback signals from adipose tissue
Leptin
Decreased production of appetitestimulators in the hypothalamusas neuropeptide Y
Increased production of appetitesuppressants in the hypothalamusas corticotrophin releasinghormone.
Increased sympathetic nerveactivity which increases themetabolic rate and energyexpenditure.
Decreased insulin secretionwhich decreases energystorage.
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Factors regulating
food intake
II) Short termregulation
Alimentary factors
Psychological factors
) Long termegulation
utritional regulation
ffect of body temperature
eedback signals fromdipose tissue
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Short term regulation
Alimentary factors
Gastrointestinalfilling.
Hormones.
Oral factors
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Short term regulation
Psychological factors
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